text: fig1 - 9 show exemplary synthetic pathways and intermediates for the synthesis of dictyostatin analogs . the synthesis of an exemplary “ bottom fragment ” 15 for making dictyostatin and analogs is shown in fig1 . 1 , 3 - propanediol 3 was elaborated via evans chiral auxiliary - based methods to the known , bis - tbs - protected homer - wadsworth - emmons product 10 in nine steps . see , phukan , p . ; sasmal , s . ; maier , m . e . eur . j . org . chem . 2003 , 1733 , and andrus , m . b . ; argade , a . b . tetrahedron lett . 1996 , 37 , 5049 . this unsaturated ester was reduced to the allylic alcohol 11 , which was protected with a trityl group and its primary tbs group removed with hf - pyridine to give alcohol 13 , which was oxidized in two steps to the carboxylic acid and coupled with the weinreb reagent to give amide 15 . the fifteen - step process from 3 to 15 yielded this intermediate in 9 . 5 % overall yield . a shorter route to 10 , also illustrated in fig1 , was also deployed . brown crotylmetalation of tbs - protected 3 - hydroxypropanal 16 ( prepared quantitatively in two steps from 3 ), was followed by protection of the resulting alcohol 17 , oso 4 - catalyzed dihydroxylation and diol cleavage with periodate , and finally homer - wadsworth - emmons homologation . this second generation route improved the overall yield of 15 from 3 to 27 %. the synthesis of an exemplary “ middle fragment ” 29 for making dictyostatin and analogs is shown in fig2 . the secondary alcohol of known compound 19 ( see , smith , a . b . ; beauchamp , t . j . ; lamarche , m . j . ; kaufman , m . d . ; qiu , y . p . ; arimoto , h . ; jones , d . r . ; kobayashi , k . j . am . chem . soc . 2000 , 122 , 8654 - 8664 . ), prepared in four steps from the ( s )- roche ester , was protected with a tbs group and the evans auxiliary was removed with libh 4 to give alcohol 21 . oxidation to the aldehyde and homer - emmons reaction gave the ester 22 . alkene reduction with nickel boride , saponification with lioh and coupling with the evans auxiliary gave amide 25 . asymmetric methylation provided one diastereomer 26 very predominantly . removal of the chiral auxiliary , tbs protection , and pmb deprotection with ddq gave the primary alcohol 28 . corey - fuchs reaction gave the desired alkyne 29 . this route from 19 to 29 proceeded in 16 % overall yield . another route to 29 , also illustrated in fig2 , involved conversion of 21 to its iodide and asymmetric alkylation with myers &# 39 ; auxiliary 30 to give amide 31 . see , myers , a . ; yang , b . y . ; chen , h . ; mckinstry , l . ; kopecky , d . j . ; gleason , j . j . am . chem . soc . 1997 , 119 , 6496 - 6511 . removal of the auxiliary gave 27 in high yield , which was converted to 29 by the steps described above . this second generation approach to 29 doubled the overall yield from 19 to 31 %. by using the enantiomer of myers &# 39 ; auxiliary 30 , the epimer of 29 at c16 ( dictyostatin numbering ) is prepared . the bottom and middle fragments were then coupled and the synthesis of dictyostatin was completed as summarized in fig3 and 4 . the route is flexible and generally allows access to many analogs . the weinreb amide 15 was reacted with two equivalents of the anion from alkyne 29 to give the coupling product 32 in high yield . reduction with the ( s , s )- noyori catalyst gave predominantly one isomer of the alcohol 33 ( see , matsumura , k . ; hashiguchi , s . ; ikariya , t . ; noyori , r . j . am . chem . soc . 1997 , 119 , 8738 - 8739 ), whose alkyne group was reduced by lindlar hydrogenation to alkene 34 . the newly generated secondary hydroxy group was protected with a tbs group to give 35 . selective deprotection of the primary tbs group with hf - pyridine in buffered pyridine at 0 ° c . gave 36 . the aldehyde formed by dess - martin oxidation was reacted with the phosphonate 38 ( prepared from 37 ) under homer - wadsworth - emmons conditions to give the conjugated alkene 39 in good yield . selective reduction with nickel boride gave the ketone 40 , which was reduced in a purposefully unselective manner with nabh 4 to give a 2 . 4 : 1 mixture of c19 epimers of 41 , with the β isomer , necessary for preparation of (−)- dictyostatin , predominating . the isomers of 41 were readily separated by silica gel chromatography . a ratio favoring 41β ( 5 : 1 ) was obtained by use of the bulkier reducing agent lial ( o - t - bu ) 3 h , whereas a 1 : 1 ratio of the α and β isomers was obtained when l - selectride was employed . alcohol 41β was protected with a tbs group to give 42 , whose pmp acetal was cleaved with dibal - h to give alcohol 43 ( fig4 ). oxidation to the aldehyde followed by nozaki - hiyama addition and peterson - type elimination installed the ( e , z )- diene to give 44 in high yield . the allylic trityl group was removed with znbr 2 to give alcohol 45 . dess - martin oxidation to the aldehyde and still - gennari reaction gave the ( e , z )- conjugated ester 46 . the pmb group was removed with ddq to give 47 and saponification with aqueous koh in etoh - thf to give acid 48 . yamaguchi macrolactonization gave 49 in good yield . global deprotection with 3n hcl in meoh - thf gave (−)- dictyostatin 1 . the sample exhibited spectral data identical to the natural product and the optical rotation matched well . thus , the previously proposed structures of dictyostatin are incorrect . also shown in fig4 are the synthetic steps leading to two representative analogs , the open - chain methyl ester 50 and c19 - epi - dictyostatin 59 . ester 50 was prepared by global removal of the tbs groups from 48 in 36 % yield . the c19 - epi analog 59 was prepared from alcohol 41α , as made in fig3 , by the same methods used for preparation of 1 . synthesis of c16 - desmethyl dictyostatin 79 , another exemplary analog , is shown in fig5 . the synthesis proceeded from ester 23 in a manner similar to the existing route to 1 , but with omission of the c16 - methyl group . thus , a considerably simpler - to - make middle fragment 64 lacking the awkward c16 stereocenter was used for construction of 79 . intermediate 23 was elongated to ester 60 by homer - wadsorth - emmons reaction . nickel boride then dibal - h reduction of the ester gave alcohol 61 in 76 % yield . the primary hydroxy group was protected with tbscl to give 62 quantitatively , then the pmb group was removed to give alcohol 63 in 90 % yield . oxidation of 63 to the aldehyde by using parikh - doering conditions , followed by corey - fuchs reaction , afforded the middle fragment alkyne 64 . the remainder of the synthesis from 64 to c16 - desmethyldictyostatin 79 was then completed by using the same synthetic pathway described above for 1 . interestingly , reduction of ketone 70 ( not shown , the desmethyl homologue of 40 ) with 3 equivalents of lial ( o - t - bu ) 3 h gave the desired 71β in 95 % yield , with only 5 % of the α - isomer . the synthesis of yet other representative analogs are shown in fig6 - 8 . these are epimers of dictyostatin at c6 , c14 and / or c19 . the alkyne 80 was added to bottom fragment 81 to give alkyne 82 in 98 % yield ( fig8 ). when this alkynyl ketone was subjected to noyori reduction conditions , one major isomer 83 was formed in 87 % yield . also in this case , about 20 mol % of the ( s , s )- noyori catalyst was preferred . the noyori product 83 was reduced by using lindlar catalyst to give the cis - alkene 84 in 90 % yield . when the reaction time was extended (˜ 1 day ), partial over - reduction of other multiple bonds occurred . in order to assign the configuration of the newly generated stereocenter at c9 , 84 was treated with tbaf to remove both tbs groups . the resulting triol was reacted with excess 2 , 2 - dimethoxypropane ( 3 . 0 equiv ) to form the acetal , whose hmqc ( 500 mhz ) nmr spectrum showed the two methyl groups of the acetonide at similar chemical shifts ( 24 . 5 ppm and 25 . 1 ppm ) and the tertiary carbon at 100 . 4 ppm . these data show an anti - relationship between the c7 and c9 hydroxy groups based on the rychnovsky method . the c9 hydroxy group in 84 was protected with a tbs group to give 85 in quantitative yield . the pmb group was then removed with ddq to give 86 in 84 % yield . the resulting secondary hydroxy group was protected again by a tbs group , giving 87 in 94 % yield . selective deprotection of the primary tbs group was accomplished in 66 % yield by treatment with hf - pyridine complex in buffered pyridine at 0 ° c . for 2 days to give 88 along with other deprotected byproducts . after the successful coupling of the middle and bottom fragments , 88 was oxidized to the aldehyde , which then was subjected to homer - emmons reaction with the phosphonate 38 , yielding 89 in 78 % yield . the alkene in α , β - unsaturated ketone 89 was reduced with nickel boride giving 90 in 76 % yield . as a side reaction , some over - reduction of the c4 - c5 alkene in the bottom fragment was also observed . the c19 ketone was reduced by nabh 4 yielding a 1 . 7 : 1 ratio of diastereomers of 91 , with the β isomer as the major ( 62 %), less polar product and the α isomer as the minor ( 36 %), more polar product . these two diastereomers could be separated by silica gel column chromatography . the newly generated c19 hydroxy group in 91β was protected by a tbs group to give 92 in 86 % yield , then the pmb acetal was cleaved with dibal - h to give the primary alcohol 93 in 97 % yield . oxidation to the aldehyde and subsequent nozaki - hiyama and peterson syn - elimination reactions gave the diene 94 in 85 % yield . removal of the trityl group in 94 with znbr 2 in ch 2 cl 2 - meoh gave 95 in 83 % yield . this was oxidized to the aldehyde and the ( e , z )- diene was installed by still - gennari reaction in 90 % yield ( fig7 ). the pmb group in 96 was removed by ddq to give 97 in 90 % yield , and the resulting methyl ester was hydrolyzed with in aqueous koh in etoh - thf . macrolactonization by the yamaguchi method gave , surprisingly , mainly the c2e , c4e macrolactone 99 in 78 % yield . final global tbs deprotection yielded 100 in 25 % yield . the c19 epimer of 100 was prepared from 91α using similar reaction pathways ( fig8 ). after yamaguchi lactonization , and global tbs deprotection , the ( e , z )- isomer 108 ( less polar , 45 %) could be isolated along with the isomerized ( e , e )- isomer 109 ( more polar , 15 %) in a 3 : 1 ratio . the methods outlined in fig1 - 8 are only exemplary of many possible variants . for example , analogs containing a c15 - c16 z - alkene can be prepared by the methods outlined in u . s . patent application ser . no . 10 / 655 , 916 . analogs lacking the c9 oxygen atom ( c9 - deoxy analogs ) can likewise be prepared by methods shown in that application . see , for example , fig8 and 11 , among others . the preferred method for forming the macrolactones ( often called macrocyclic lactones or macrolides ) is the yamaguchi lactonization . see , for example , inanaga , j . ; kuniko , h . ; hiroko , s . ; katsuki , t . ; yamaguchi , m . bull . chem . soc . jpn . 1979 , 52 , 1989 . an example of the yamaguchi lactonization is the conversion of hydroxy acid 48 to lactone 49 in fig4 . many other commons conditions suitable to effect macrolactone formation from hydroxy acids are well known to those skilled in the art , and these can also be used . see , for example , kirst , h . a . macrolides . large ring molecules ; wiley : ny ; 1996 ; pp 345 - 375 , and boeckman , r . k ., jr ; goldstein , s . w . the total synthesis of macrocyclic lactones . the total synthesis of natural products ; wiley : new york , 1988 ; p 1 . the steps of semi - reduction of the c10 - c11 alkyne , asymmetric reduction of the c9 ketone and ( optionally ) protection of the resulting alcohol can be conducted under and assortment of different reaction conditions . for one example , see the conversion of alkynyl ketone 32 to alkynyl alcohol 33 , to alkenyl alcohol 34 , to silyl ether 35 in fig3 . the preferred conditions for reduction of the ketone involve use of the noyori reagent , see k . matsumura , s . hashiguchi , t . ikariya , r . noyori , j . am . chem . soc . 1997 , 119 , 8738 - 39 . however , many other common ketone reducing agents , both chiral and achiral , can also be used . see , for example , itsuno , s . enantioselective reduction of ketones . org . react . ( n . y . ) 1998 , 52 , 395 - 576 . in cases were two epimers of the alcohol are formed , chromatographic separation is used to isolate the individual epimers ( see , for example , separation of 41 in fig3 ). the lindlar reduction is the preferred method of semi - reduction of the alkyne to the z - alkene , but other methods can also be used . see for example , siegel , s . heterogeneous catalytic hydrogenation of c ═ c and alkynes . comprehensive organic synthesis ; pergamon press : oxford , 1991 ; pp 417 , and takaya , h . homogeneous catalytic hydrogenation of c ═ c and alkynes . comprehensive organic synthesis ; pergamon press : oxford , 1991 ; pp 443 . the reactions in this sequence of steps can also be conducted in several orders . the preferred order is semi - reduction of the c10 - c11 alkyne , followed by asymmetric reduction of the c9 ketone followed by ( optionally ) protection of the resulting alcohol . other orders of reactions are asymmetric reduction of the ketone , protection of the alcohol and semi - reduction of the alkyne , or asymmetric reduction of the ketone , semi - reduction of the alkyne and protection of the alcohol . the preceding steps of coupling of an alkynyl anion with an activated carboxylic acid , see for example conversion of 15 and 29 to 32 in fig3 , also can be conducted under different sets of conditions . a preferred method is the deprotonation of the alkyne with a strong base , for example buli , followed by addition of a carboxylic acid derivative that is activated with a suitable leaving group . preferred activated carboxylic acids for acylation ( acylating agents ) are weinreb amides where the leaving group is the n - methoxy - n - methyl amide group . many other agents such as esters , acid halides , acid imidazolides , etc . can also be used . these have standard leaving groups such as alkoxide , imidazole and halide . the alkynyl anion can also be generated in situ from a silylalkyne by desilylation or from a geminal - haloalkene by treatment with two or more equivalents of a lithiating agent like buli . in an alternative route , the alkynyl anion can be reacted with an aldehyde instead of an activated carboxylic acid to produce a c9 alcohol directly after workup . this route is more direct , but mixtures of epimers at c9 may result and chromatographic separation of the epimers may be required . one epimer of a c9 ( or other ) alcohol can be converted to the other by a mitsunobu reaction . lactam analogs of dictyostatin are important as anticancer agents because of their increased hydrolytic stability compared to the lactones , both in vivo and in vitro . these analogs are readily made by starting with intermediates of the current invention , as exemplified in fig9 . standard oxidation of the free c21 alcohol of 110 to a ketone followed by reductive amination provides 111 . if desired , the c21 amine stereoisomers can be separated by chromatography . hydrolysis of the ester to the acid followed by macrolactamization provides lactam 112 . the specific example of dictyostatin macrolactam 115 , made for example by the sequence 113 → 114 → 115 , is exemplary of a lactam analog of this invention . the steps in the sequence can be conducted in different orders and also on different intermediates . when the c21 nitrogen atom is installed earlier in the synthesis , it is optionally protected with a standard nitrogen protecting group for the subsequent steps prior to macrolactamization . in another approach , this nitrogen can be installed by a mitsunobu reaction of a suitably acidic nitrogen nucleophile ( for example , azide ) with a c21 alcohol . this reaction occurs with inversion , so the configuration of c23 is chosen accordingly . for exemplary methods and conditions of reductive amination , see baxter , e . w . ; reitz , a . b . reductive aminations of carbonyl compounds with borohydride and borane reducing agents . org . react . ( n . y . ) 2002 , 59 , 1 - 714 . methods of synthesizing macrolactams ( macrocyclic lactams ) are related to those for macrolactones . for exemplary methods and conditions , see nubbemeyer , u . top . curr . chem . 2001 , 216 , 125 - 196 . for exemplary methods and conditions for mitsunobu reactions , see hughes , d . l . org . prep . proced . int . 1996 , 28 , 127 - 164 . the abilities of the new compounds to cause tubulin polymerization were determined under reaction conditions consisting of purified bovine brain tubulin ( 1 mg / ml ) in the presence or absence of microtubule - associated proteins ( maps , 0 . 75 mg / ml ) and gtp ( 100 μm ). test agents were initially screened at 10 and 40 μm . in these experiments , test agent - induced assembly of soluble tubulin into polymer , with respect to the presence and absence of cofactors and at different temperatures , was monitored in a multi - cuvette , temperature - controlled spectrophotometer via development of turbidity in the solution . the initial temperature was closely controlled at 0 ° c ., then rapidly raised to 10 ° c ., to 20 ° c ., then finally to 30 ° c . to determine both the temperature at which a test agent induced assembly as well as the extent of agent - induced assembly . the temperature increases were followed by a rapid decrease in temperature back to 0 ° c . to determine the cold - stability of polymer formed . the effects of dictyostatin 1 and discodermolide 2 were similar and far more potent than those of paclitaxel . the c16 - desmethyl compound 79 is especially potent among the analogs . fig1 shows the simplest of its turbidity profiles in comparison to that of dictyostatin 1 in a tubulin - only ( no maps , no gtp , assembly supported by monosodium glutamate ) assay wherein initial temperature was 0 ° c . for 2 min , followed by rapid rise in temperature to 30 ° c . for 20 min , then rapid decrease to 0 ° c . turbidity profiles showed that analogs 50 and 59 also caused tubulin assembly at temperatures lower than 30 ° c . the results showed that all of the compounds had effects on the isolated target , tubulin , but with a range of potencies . representative analogs were examined for their antiproliferative activities against human ovarian carcinoma 1a9 cells and their paclitaxel - resistant mutants , 1a9 / ptx10 and 1a9 / ptx22 . each of these resistant lines contains single mutations in the major β - tubulin gene that confer to the cells , which do not express drug efflux pumps , appreciable tolerance to paclitaxel . paclitaxel had subnanomolar potency against the parental 1a9 cells , but the mutant cells showed ca . 90 - and 70 - fold resistance to the drug ( table 1 ). analogs 50 and 59 gave gi50 values in the mid - nanomolar range . c6 - epi , c14 - epi - c19 - epi - dictyostatin 108 and its c2e - diene derivative 109 were antiproliferative agents , giving mid micromolar gi50 values . even though 100 also had three stereo / geometric alterations ( c2e , c6 - epi , c14 - epi ), it was a more potent antiproliferative agent than 108 and 109 , showing high nanomolar gi50 values . with one notable exception ( vide infra ), the fold - resistance values for 1 and its analogs against 1a9 / ptx10 and 1a9 / ptx22 cell lines were much lower than that observed for paclitaxel . the one exception was compound 79 , which appeared to be essentially equipotent to 1 against the parental 1a9 cells and the ala364 → thr β - tubulin mutant 1a9 / ptx22 cells , but experienced resistance from the phe270 → val β - tubulin mutant 1a9 / ptx10 cells . because these mutant cells are not clinically relevant , the result of reduced potency is primarily of mechanistic importance . dictyostatin and representative analogs were evaluated in a quantitative assay for their ability to promote tubulin polymerization . the ec 50 value ( defined as test agent concentration required to polymerize 50 % of tubulin compared to control ) observed for dictyostatin 1 under these conditions was 3 . 1 ± 0 . 2 μm , similar to that obtained for discodermolide 2 ( 3 . 6 ± 0 . 4 μm ). both were far superior to paclitaxel , which gave an ec 50 value of 25 ± 3 μm . the c16 - desmethyl analog 79 an ec 50 of 14 ± 7 μm . when the percent polymer formed was determined in the reactions , a comparison of the activities of all the analogs could be made . compounds 50 and 59 showed moderate activity . these ec 50 data correlated well with the relative antiproliferative potencies of the analogs . the abilities of test agents to inhibit the binding of radiolabeled forms of the microtubule stabilizers paclitaxel , discodermolide and epothilone b from tubulin polymer were determined . dictyostatin 1 was equipotent to discodermolide in inhibition of the binding of radiolabeled paclitaxel and epothilone b to microtubules . these two compounds were the most potent of all agents tested . the open chain methyl ester 50 and the 16 - desmethyl analog 79 were ca . 60 % as potent as 1 in inhibiting the binding of radiolabeled paclitaxel to microtubules . hela cells were plated on collagen - coated 384 - well microtiter plates , allowed to attach , then treated for 24 h with test agents . test agent concentrations began at 1 μm , and two - fold dilutions were made to levels below 1 nm . after the treatment period , the cells were fixed with formalin and their chromatin stained with hoechst 33342 . cells were permeabilized and treated with primary antibodies for α - tubulin and phosphohistone h3 , and then with fluorophore - labeled secondary antibodies . the three fluorescent channels were then examined on an arrayscan ii , which gives quantitative pixel distribution and density information in each channel on a per cell basis . dictyostatin 1 was the most potent of all compounds tested , followed by paclitaxel , discodermolide and the 16 - desmethyl analog 79 . a solution of triethyl phosphonoacetate ( 3 . 5 ml , 17 . 6 mmol ) was added to a cooled ( 0 ° c .) stirred suspension of nah ( 0 . 43 g , 17 . 0 mmol , 95 % dispersion in mineral oil ) in thf ( 46 ml ) dropwise over a 10 min period . the mixture was brought to room temperature with a water bath ( 30 min ) and then cooled back to − 78 ° c . and the aldehyde ( 2 . 73 g , 7 . 58 mmol ) in thf ( 5 ml ) was added . the resulting mixture was stirred for 1 h at 0 ° c . then ph7 phosphate buffer solution ( 10 ml ) and et 2 o ( 50 ml ) were added . the mixture was allowed to warm to room temperature and the phases were separated . the organic phase was washed with sat &# 39 ; d nh 4 cl solution ( 30 ml ) and brine ( 30 ml ), dried with mgso 4 , filtered and concentrated to give oily crude product . purification by flash chromatography ( etoac / hexane 1 : 9 ) afforded pure ester 10 ( 2 . 92 g , 59 % for 2 steps ) as a colorless oil : ir ( chcl 3 ) 2956 , 2930 , 2857 , 1724 , 1651 , 1472 , 1463 , 1367 , 1256 , 1180 , 1098 , 1036 , 836 , 775 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ6 . 88 ( dd , j = 15 . 8 , 7 . 6 hz , 1h ), 5 . 74 ( d , j = 15 . 8 hz , 1h ), 4 . 19 ( q , j = 7 . 1 hz , 2h ), 3 . 79 ( ddd , j = 6 . 7 , 4 . 7 , 4 . 4 hz , 1h ), 3 . 59 ( m , 2h ), 2 . 43 ( m , 1h ), 1 . 53 ( m , 3h ), 1 . 22 ( t , j = 7 . 1 hz , 3h ), 1 . 01 ( d , j = 6 . 8 hz , 3h ), 0 . 83 ( s , 18h ), 0 . 02 ( m , 12h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 4 , 150 . 9 , 121 . 3 , 71 . 8 , 59 . 9 , 59 . 5 , 42 . 0 , 36 . 8 , 25 . 82 , 25 . 78 , 26 . 1 , 18 . 1 , 18 . 0 , 14 . 4 , 14 . 2 , − 4 . 6 , − 4 . 7 , − 5 . 4 ; lrms ( ei ) 415 ( m − ch 3 ), 373 , 303 , 147 ; hrms ( ei ) calcd for c 21 h 43 o 4 si 415 . 2710 ( m − ch 3 ), found 415 . 2712 ; [ α ] 20 d + 3 . 8 ( c 0 . 21 , chcl 3 ). dibal - h ( 26 . 5 ml , 26 . 5 mmol , 1 . 0 m solution in hexane ) was added to the ester 10 ( 3 . 14 g . 7 . 30 μmol ) in ch 2 cl 2 ( 35 ml ) at − 78 ° c . dropwise and stirred for 1 h . the reaction mixture was quenched by etoac ( 5 ml ) and sat &# 39 ; d sodium potassium tartrate solution ( 20 ml ) followed by vigorous stirring for 4 h . the aqueous phase was extracted with ch 2 cl 2 ( 3 × 30 ml ) and the combined organic layers were washed with brine ( 10 ml ). after drying over mgso 4 and evaporation under vacuum , flash column chromatography ( hexane / etoac 4 : 1 ) provided 2 . 75 g of alcohol 11 ( 97 %) as a colorless oil : ir ( chcl 3 ) 3349 , 2956 , 2928 , 2857 , 1471 , 1462 , 1255 , 1099 , 836 , 774 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ5 . 57 ( m , 2h ), 4 . 03 ( m , 2h ), 3 . 70 ( ddd , j = 9 . 7 , 6 . 0 , 3 . 8 hz , 1h ), 3 . 59 ( m , 2h ), 2 . 27 ( m , 1h ), 2 . 00 ( s , 1h ), 1 . 53 ( q , j = 6 . 5 hz , 2h ), 0 . 96 ( d , j = 6 . 9 hz , 3h ), 0 . 85 ( s , 9h ), 0 . 84 ( s , 9h ), 0 . 00 ( m , 12h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 134 . 7 , 129 . 2 , 72 . 4 , 63 . 6 , 60 . 1 , 41 . 8 , 36 . 3 , 25 . 9 , 18 . 2 , 18 . 0 , 15 . 1 , 10 . 7 , − 4 . 6 , − 5 . 4 ; lrms ( ei ) 370 ( m − h 2 o ), 303 , 171 , 147 ; hrms ( ei ) calcd for c 20 h 42 o 2 si 2 370 . 2723 ( m − h 2 o ), found 370 . 2725 ; [ α ] 20 d − 3 . 0 ( c 0 . 57 , chcl 3 ). trityl chloride ( 4 . 1 g , 14 . 7 mmol ) and dmap ( 1 . 8 g , 14 . 7 mmol ) were added to a solution of alcohol 11 ( 2 . 75 g , 7 . 1 mmol ) in pyridine ( 71 ml ). the mixture was heated to reflux for 18 h , cooled to ambient temperature and added to a solution of sat &# 39 ; d cuso 4 ( 200 ml ). the mixture was extracted with et 2 o ( 2 × 20 ml ) and the combined organic extracts were washed sat &# 39 ; d cuso 4 ( 2 × 20 ml ). the organic layer was separated , dried ( mgso 4 ), filtered , and concentrated in vacuo . flash column chromatography ( etoac / hexane 1 : 19 ) provided 12 ( 4 . 46 g , quantitative ) as a pale yellow oil : ir ( chcl 3 ) 2954 , 2856 , 1471 , 1448 , 1254 , 1095 , 835 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 56 ( m , 6h ), 7 . 32 ( m , 9h ), 5 . 79 ( dd , j = 15 . 6 , 6 . 7 hz , 1h ), 5 . 65 ( dd , j = 15 . 7 , 5 . 0 hz , 1h ), 3 . 85 ( m , 1h ), 3 . 74 ( m , 1h ), 3 . 66 ( d , j = 4 . 9 hz , 1h ), 2 . 43 ( m , 1h ), 1 . 70 ( q , j = 6 . 5 hz , 2h ), 1 . 21 ( d , j = 6 . 9 hz , 3h ), 0 . 99 ( s , 9h ), 0 . 97 ( s , 9h ), 0 . 154 ( s , 3h ), 0 . 150 ( s , 3h ), 0 . 13 ( s , 3h ), 0 . 12 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 4 , 134 . 2 , 128 . 7 , 127 . 7 , 126 . 9 , 126 . 8 , 86 . 8 , 72 . 6 , 65 . 1 , 60 . 2 , 42 . 1 , 36 . 6 , 26 . 0 , 18 . 3 , 18 . 1 , 15 . 3 , − 4 . 4 , − 5 . 3 ; lrms ( est ) 653 . 3 [ m + na ]+, 422 . 4 , 243 . 2 ; hrms ( esi ) calcd for c 39 h 58 o 3 si 2 na 653 . 3822 [ m + na ] + , found 653 . 3851 ; [ α ] 20 d − 1 . 9 ( c 0 . 42 , chcl 3 ). hf - pyridine in pyridine ( 40 ml , prepared by slow addition of 12 ml pyridine to 3 ml hf - pyridine complex followed by dilution with 25 ml thf ) was added to a solution of tbs ether 12 ( 4 . 46 g , 7 . 07 mmol ) in thf ( 10 ml ). the mixture was stirred overnight at room temperature and quenched with sat &# 39 ; d nahco 3 ( 100 ml ). the aqueous layer was separated and extracted with et 2 o ( 3 × 50 ml ). the combined organic layers were washed with sat &# 39 ; d cuso 4 ( 3 × 50 ml ), dried over mgso 4 , and concentrated . flash column chromatography ( etoac / hexane 1 : 4 ) afforded 3 . 26 g ( 89 %) of alcohol 13 as a colorless oil : ir ( chcl 3 ) 3407 , 2955 , 2928 , 2856 , 1490 , 1471 , 1448 , 1254 , 1058 , 1031 , 836 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 57 ( m , 6h ), 7 . 37 ( m , 9h ), 5 . 78 ( dd , j = 15 . 6 , 6 . 5 hz , 1h ), 5 . 73 ( dt , j = 15 . 5 , 4 . 8 hz , 1h ), 3 . 91 ( m , 1h ), 3 . 82 ( d , j = 5 . 9 hz , 2h ), 3 . 69 ( d , j = 4 . 4 hz , 2h ), 2 . 51 ( m , 1h ), 2 . 22 ( br , 1h ), 1 . 77 ( m , 2h ), 1 . 13 ( d , j = 6 . 8 hz , 3h ), 1 . 03 ( s , 9h ), 0 . 21 ( s , 3h ), 0 . 19 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 2 , 134 . 1 , 128 . 6 , 127 . 7 , 127 . 1 , 126 . 9 , 86 . 8 , 74 . 3 , 64 . 9 , 60 . 4 , 42 . 0 , 34 . 8 , 25 . 9 , 18 . 0 , 14 . 5 , − 4 . 4 , − 4 . 6 ; lrms ( esi ) 539 . 2 [ m + na ]+, 243 . 2 ; hrms ( esi ) calcd for c 33 h 44 o 3 si 1 na 539 . 2957 [ m + na ] + , found 539 . 2976 ; [ α ] 20 d − 2 . 8 ( c 2 . 0 , chcl 3 ). sulfur trioxide pyridine complex ( 3 . 02 g , 19 . 1 mmol ) was added to a stirred solution of alcohol 13 ( 3 . 26 g , 6 . 31 mmol ) and triethylamine ( 2 . 6 ml , 19 . 1 mmol ) in anhydrous ch 2 cl 2 ( 6 ml ) and dmso ( 12 ml ) at 0 ° c . the reaction mixture was stirred at the ambient temperature for 1 h . the mixture was diluted with et 2 o ( 100 ml ) and washed with aqueous 0 . 5 n hcl ( 50 ml ) and brine ( 10 ml ). the separated organic layer was dried over mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 4 : 1 ) provided the crude aldehyde as a colorless oil , which was used without further purification . a solution of the aldehyde in thf ( 25 ml ) and h 2 o ( 12 ml ) was treated with 2 - methyl - 2 - butene in thf ( 2m , 18 ml , 9 . 0 mmol ), nah 2 po 4 . h 2 o ( 2 . 6 g , 18 . 8 mmol ) and naclo 2 ( 2 . 1 g , 18 . 6 mmol ). the reaction mixture was stirred for 2 h , diluted with 1n hcl ( 20 ml ) and extracted with ch 2 cl 2 ( 2 × 40 ml ). the combined organic layers were dried over mgso 4 , concentrated in vacuo and the crude acid was used for the next reaction without further purification . n , o - dimethylhydroxylamine hydrochloride ( 0 . 62 g , 6 . 36 mmol ), et 3 n ( 0 . 88 ml , 6 . 31 mmol ), dmap ( 0 . 63 mmol ) were successively added to a solution of the crude acid in ch 2 cl 2 ( 10 ml ). the reaction mixture was cooled to 0 ° c . and dcc ( 1 . 30 g , 6 . 30 mmol ) was added . the mixture was stirred at ambient temperature for 15 h and filtered . the filtrate was washed with 0 . 5 n hcl , saturated aqueous nahco 3 , and brine , dried over anhydrous mgso 4 and concentrated . purification by column chromatography over silica gel ( hexane / etoac 4 : 1 ) gave the weinreb amide 15 ( 2 . 65 g , 73 % for 3 steps ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2855 , 1663 , 1448 , 1252 , 1083 , 1032 , 836 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 58 m , 6h ), 7 . 37 ( m , 9h ), 5 . 89 ( dd , j = 15 . 6 , 7 . 6 hz , 1h ), 5 . 72 ( dt , j = 15 . 6 , 5 . 2 hz , 1h ), 4 . 38 ( ddd , j = 8 . 0 , 5 . 0 , 3 . 0 hz , 1h ), 3 . 74 ( s , 3h ), 3 . 70 ( d , j = 5 . 1 hz , 2h ), 3 . 27 ( s , 3h ), 2 . 79 ( dd , j = 15 . 1 , 7 . 4 hz , 1h ), 2 . 52 ( m , 2h ), 1 . 20 ( d , j = 6 . 9 hz , 3h ), 1 . 02 ( s , 9h ), 0 . 22 ( s , 3h ), 0 . 16 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 172 . 6 , 144 . 2 , 133 . 3 , 128 . 5 , 127 . 7 , 127 . 5 , 126 . 8 , 86 . 7 , 72 . 4 , 64 . 8 , 61 . 2 , 42 . 4 , 36 . 3 , 31 . 9 , 25 . 8 , 18 . 0 , 15 . 7 , − 4 . 6 , − 5 . 0 ; lrms ( esi ) 596 . 2 [ m + na ] + , 449 . 2 , 243 . 0 ; hrms ( esi ) calcd for c 35 h 47 o 4 nsina 596 . 3172 [ m + na ] + , found 596 . 3165 ; [ α ] 20 d 14 . 7 ( c 0 . 65 , chcl 3 ). 2 , 6 - lutidine ( 5 . 14 ml , 44 . 2 mmol ) and tbsotf ( 9 . 36 ml , 40 . 8 mmol ) were added to a solution of 19 ( 15 . 0 g , 33 . 9 mmol ) in ch 2 cl 2 ( 340 ml ) stirred at 0 ° c . the mixture was stirred at 0 ° c . for 2 h and then quenched by the addition of saturated aqueous nahco 3 . the phases were separated and the aqueous layer was extracted with ch 2 cl 2 . the combined organic phases were washed with 0 . 5 m aqueous nahso 4 . the organic phase was dried over na 2 so 4 , filtered and concentrated under reduced pressure . the residue was purified by flash chromatography ( hexane / etoac 4 : 1 ) to give 20 ( 17 . 9 g , 95 %) as a colorless oil : ir ( film ) 1781 , 1696 , 1513 , 1383 , 1248 , 1209 , 1110 , 1042 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 35 - 7 . 28 ( m , 7h ), 6 . 85 ( d , j = 8 , 7 hz , 1h ), 4 . 49 ( m , 1h ), 4 . 38 ( d , j = 11 . 7 hz , 1h ), 4 . 34 ( d , j = 11 . 7 hz ), 4 . 03 ( m , 3h ), 3 . 81 ( m , 3h ), 3 . 77 ( s , 3h ), 3 . 54 ( dd , j = 9 . 2 , 5 . 6 hz , 1h ), 3 . 22 ( dd , j = 13 . 3 , 3 . 1 hz , 1h ), 3 . 17 ( dd , j = 9 . 1 , 5 . 9 hz , 1h ), 2 . 72 ( dd , j = 13 . 3 , 9 . 6 hz , 1h ), 1 . 97 ( m , 1h ), 1 . 25 ( d , j = 6 . 5 hz , 3h ), 1 . 02 ( d , j = 7 . 0 hz , 3h ), 0 . 91 ( s , 9h ), 0 . 07 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 176 . 4 , 159 . 4 , 153 . 1 , 135 . 8 , 131 . 1 , 129 . 8 , 129 . 3 , 129 . 2 , 127 . 6 , 75 . 6 , 72 . 9 , 72 . 0 , 66 . 1 , 55 . 8 , 55 . 6 , 41 . 9 , 39 . 3 , 38 . 0 , 26 . 4 , 18 . 7 , 15 . 3 , 15 . 2 , − 3 . 5 , − 3 . 6 ; hrms ( esi ) calcd for c 31 h 45 no 6 sina 578 . 2914 [ m + na ] + , found 578 . 2923 ; [ α ] 20 d − 8 . 1 ( c 7 . 6 , chcl 3 ). dry meoh ( 1 . 05 ml , 26 . 0 mmol ) then libh 4 ( 13 ml , 2 . 0 m solution in thf , 26 mmol ) were added to a stirred solution of 20 ( 4 . 79 g , 8 . 62 mmol ) in thf ( 75 ml ) at 0 ° c . the resulting mixture was stirred at 0 ° c . for 45 min and at room temperature for 1 h . the solution was cooled to 0 ° c . and treated carefully with a 1 . 0 m aqueous naoh ( 50 ml ). the phases were separated and the aqueous phase was extracted with ch 2 cl 2 . the combined organic phases were washed with brine , dried over mgso 4 , filtered and concentrated under reduced pressure . the residue was purified by flash chromatography ( hexane / etoac 7 : 3 ) to give the alcohol 21 ( 2 . 98 g , 90 %) as a colorless oil : ir ( film ) 3425 , 1613 , 1513 , 1463 , 1249 , 1091 , 1037 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 26 ( d , j = 8 . 5 hz , 2h ), 6 . 88 ( d , j = 8 . 5 hz , 2h ), 4 . 47 ( d , j = 11 . 7 hz , 1h ), 4 . 40 ( d , j = 11 . 7 hz , 1h ), 3 . 84 ( s , 3h ), 3 . 75 ( dd , j = 5 . 7 , 2 . 9 hz , 1h ), 3 . 52 ( m , 3h ), 3 . 28 ( dd , j = 9 . 1 , 7 . 1 hz , 1h ), 2 . 10 ( br , 1h ), 2 . 05 ( m , 1h ), 1 . 93 - 1 . 81 ( m , 1h ), 0 . 97 ( d , j = 7 . 0 hz , 3h ), 0 . 90 ( s , 9h ), 0 . 87 ( d , j = 7 . 1 hz , 3h ), 0 . 07 ( s , 3h ), 0 . 05 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 130 . 7 , 129 . 3 , 113 . 8 , 74 . 8 , 72 . 8 , 72 . 7 , 66 . 3 , 55 . 4 , 39 . 0 , 37 . 7 , 26 . 2 , 18 . 4 , 15 . 2 , 12 . 0 , − 4 . 1 ; hrms ( esi ) calcd for c 18 h 31 o 3 sina 323 . 2042 [ m + na ] + , found 323 . 2035 ; [ α ] 20 d − 0 . 76 ( c 2 . 9 , chcl 3 ). the procedure for 10 was used with the aldehyde from 21 ( 17 . 5 g , 31 . 6 mmol ), py . so 3 ( 15 . 2 g , 95 . 5 mmol ) and et 3 n ( 13 . 3 ml , 95 . 5 mmol ), nah ( 0 . 90 g , 39 . 7 mmol ) and triethylphosphonoacetate ( 7 . 2 ml , 40 . 3 mmol ) to yield 8 . 96 g ( 63 % for 3 steps ) of the ester 22 by flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 2957 , 2931 , 2856 , 1720 , 1651 , 1613 , 1513 , 1463 , 1366 , 1250 , 1180 , 1093 , 1077 , 837 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 31 - 7 . 27 ( m , 2h ), 7 . 03 ( dd , j = 15 . 8 , 7 . 8 hz , 1h ), 6 . 93 - 6 . 91 ( m , 2h ), 5 . 83 ( dd , j = 15 . 8 , 1 . 3 hz , 1h ), 4 . 48 - 4 . 40 ( m , 2h ), 4 . 23 ( q , j = 7 . 1 hz , 2h ), 3 . 84 ( s , 3h ), 3 . 67 ( m , 1h ), 3 . 52 ( m , 1h ), 3 . 30 ( dd , j = 9 . 1 , 7 . 2 hz , 1h ), 2 . 59 ( m , 1h ), 2 . 00 ( m , 1h ), 1 . 33 ( t , j = 7 . 1 hz , 3h ), 1 . 09 ( d , j = 6 . 8 hz , 3h ), 1 . 01 ( d , j = 7 . 0 hz , 3h ), 0 . 94 ( s , 9h ), 0 . 08 ( m , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 5 , 159 . 0 , 152 . 7 , 130 . 6 , 129 . 0 , 120 . 4 , 113 . 6 , 76 . 8 , 72 . 5 , 71 . 8 , 60 . 0 , 55 . 1 , 40 . 2 , 38 . 0 , 26 . 0 , 18 . 2 , 14 . 8 , 14 . 3 , 14 . 2 , − 4 . 0 , − 4 . 2 ; lrms ( esi ) 473 . 2 [ m + na ]+; hrms ( esi ) calcd for c 25 h 42 o 5 sina 473 . 2699 [ m + na ] + , found 473 . 2716 ; [ α ] 20 d − 28 . 3 ( c 0 . 41 , chcl 3 ). nicl 2 . 6h 2 o ( 2 . 4 g , 10 . 1 mmol ) then portionwise nabh 4 ( 1 . 50 g , 39 . 7 mmol ) were added to a stirred solution of unsaturated ketone 22 ( 8 . 96 g , 19 . 9 μmol ) in meoh ( 66 ml ), thf ( 20 ml ) at 0 ° c . after 1 h , the solvent was evaporated and filtered with celite using et 2 o as an eluent ( 60 ml ). the organic phase was concentrated and the residue was purified by flash chromatography ( etoac / hexane 1 : 9 ) to yield 8 . 76 g of 23 ( 97 %) as a colorless oil : ir ( chcl 3 ) 2957 , 2856 , 1737 , 1613 , 1513 , 1463 , 1374 , 1249 , 1172 , 1091 , 1038 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 40 - 7 . 37 ( m , 2h ), 7 . 02 - 6 . 99 ( m , 2h ), 4 . 59 - 4 . 50 ( m , 2h ), 4 . 25 ( q , j = 7 . 1 hz , 2h ), 3 . 91 ( s , 3h ), 3 . 66 - 3 . 62 ( m , 2h ), 3 . 40 ( dd , j = 8 . 8 , 7 . 3 hz , 1h ), 2 . 52 - 2 . 33 ( m , 2h ), 2 . 13 - 2 . 02 ( m , 1h ), 1 . 90 - 1 . 82 ( m , 1h ), 1 . 78 - 1 . 57 ( m , 2h ), 1 . 38 ( t , j = 7 . 1 hz , 3h ), 1 . 09 ( d , j = 6 . 9 hz , 3h ), 1 . 03 ( s , 9h ), 1 . 00 ( d , j = 6 . 5 hz , 3h ), 0 . 19 ( s , 3h ), 0 . 18 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 173 . 6 , 158 . 9 , 130 . 7 , 129 . 0 , 113 . 5 , 76 . 8 , 72 . 5 , 60 . 0 , 55 . 0 , 38 . 0 , 35 . 6 , 32 . 5 , 29 . 9 , 26 . 0 , 18 . 3 , 14 . 9 , 14 . 1 , 13 . 7 , − 3 . 9 , − 4 . 2 ; lrms ( esi ) 475 . 3 [ m + na ] + ; hrms ( esi ) calcd for c 25 h 44 o 5 sina 475 . 2856 [ m + na ] + , found 473 . 2877 ; [ α ] 20 d − 6 . 0 ( c 1 . 9 , chcl 3 ). aqueous lioh ( 1n , 193 ml , 0 . 19 mol ) was added to a thf - h 2 o solution of 23 ( 8 . 76 g , 19 . 4 mmol ). the resulting solution was warmed to 60 ° c . and stirred with heating for 6 h . aqueous 1n hcl was added to give a neutral ph and the mixture was extracted with ch 2 cl 2 , dried over mgso4 , filtered and evaporated to yield 8 . 22 g of crude acid 24 , which was used without further purification : 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 24 - 7 . 22 ( m , 2h ), 6 . 86 - 6 . 83 ( m , 2h ), 4 . 39 ( m , 2h ), 3 . 77 ( s , 3h ), 3 . 69 ( q , j = 7 . 0 hz , 1h ), 3 . 52 ( m , 1h ), 3 . 47 ( q , j = 7 . 0 hz , 1h ), 3 . 19 ( t , j = 8 . 5 hz , 1h ), 2 . 16 ( m , 1h ), 1 . 90 ( m , 1h ), 1 . 65 - 1 . 51 ( m , 2h ), 1 . 21 ( t , j = 7 . 0 hz , 2h ), 0 . 92 - 0 . 85 ( m , 12h ), 0 . 81 ( d , j = 6 . 3 hz , 3h ), 0 . 00 ( m , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 181 . 0 , 158 . 9 , 130 . 6 , 129 . 1 , 113 . 6 , 72 . 5 , 65 . 8 , 58 . 0 , 55 . 1 , 37 . 8 , 30 . 6 , 26 . 1 , 18 . 3 , 18 . 1 , 15 . 2 , 14 . 0 , − 3 . 5 , − 4 . 1 . a solution of the acid 24 ( 8 . 22 g , 19 . 4 mmol ) and et 3 n ( 5 . 40 ml , 38 . 8 mmol ) in 100 ml of dry thf was cooled to − 78 ° c . and treated dropwise with pivaloyl chloride ( 2 . 86 g , 23 . 3 mmol ), stirred in the cold for 2 h and warmed to 0 ° c . prior to the addition of the oxazolidinone ( 3 . 5 g , 19 . 8 mmol ) and licl ( 2 . 46 g , 58 . 8 mmol ). this mixture was stirred overnight at room temperature and diluted with water ( 200 ml ). the separated aqueous phase was extracted with ether ( 100 ml ) and the combined organic layers were dried and evaporated to give a residue that was chromatographed to yield 7 . 91 g ( 70 % for 2 steps ) of imide 25 by flash column chromatography ( etoac / hexane 1 : 4 ) as a colorless oil : 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 41 - 7 . 23 ( m , 7h ), 6 . 94 - 6 . 91 ( m , 2h ), 4 . 71 ( m , 1h ), 4 . 51 ( d , j = 11 . 6 hz , 1h ), 4 . 46 ( d , j = 11 . 6 hz , 1h ), 4 . 25 - 4 . 16 ( m , 2h ), 3 . 84 ( s , 3h ), 3 . 63 - 3 . 58 ( m , 2h ), 3 . 37 - 3 . 31 ( m , 2h ), 3 . 14 - 3 . 04 ( m , 1h ), 2 . 94 - 2 . 86 ( m , 1h ), 2 . 79 ( dd , j = 13 . 3 , 9 . 7 hz , 1h ), 2 . 04 ( m , 1h ), 1 . 87 - 1 . 60 ( m , 3h ), 1 . 03 ( d , j = 6 . 9 hz , 3h ), 0 . 99 - 0 . 97 ( m , 12h ), 0 . 14 ( s , 3h ), 0 . 12 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 173 . 1 , 158 . 8 , 153 . 3 , 135 . 2 , 130 . 7 , 129 . 3 , 129 . 0 , 128 . 8 , 127 . 1 , 113 . 5 , 77 . 1 , 72 . 5 , 72 . 4 , 65 . 9 , 55 . 1 , 54 . 9 , 37 . 9 , 37 . 7 , 35 . 6 , 33 . 7 , 29 . 2 , 26 . 0 , 18 . 3 , 14 . 9 , 13 . 9 , − 3 . 8 , − 4 . 2 . nahmds ( 1 m in thf , 14 . 9 ml , 14 . 9 mmol ) was added dropwise over a 30 min period to a cooled (− 78 ° c .) suspension of the imide 25 ( 7 . 91 g , 13 . 6 mmol ) in thf ( 45 ml ). after 15 min of stirring , the resulting cold solution was treated with mei ( 2 . 53 ml , 40 . 8 mmol ) and allowed to stir at − 78 ° c . for 3 h before being warmed to 25 ° c . overnight ( 12 h ) the reaction was quenched with h 2 o ( 100 ml ), and the aqueous layer was extracted with et 2 o ( 3 × 150 ml ). the combined organic extracts were dried ( mgso 4 ), concentrated in vacuo and chromatographed ( etoac / hexane 1 : 9 ) to provide 5 . 97 g ( 74 %) of 26 as a colorless oil : 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 42 - 7 . 26 ( m , 7h ), 6 . 95 - 6 . 92 ( m , 2h ), 4 . 71 ( m , 1h ), 4 . 51 ( m , 2h ), 4 . 18 ( m , 2h ), 3 . 95 ( m , 1h ), 3 . 84 ( s , 3h ), 3 . 63 ( dd , j = 8 . 9 , 3 . 8 hz , 1h ), 3 . 57 ( dd , j = 6 . 4 , 2 . 7 hz , 1h ), 3 . 35 ( t , j = 8 . 5 hz , 1h ), 3 . 28 ( dd , j = 13 . 3 , 3 . 1 hz , 1h ), 2 . 83 ( dd , j = 13 . 3 , 9 . 4 hz , 1h ), 2 . 10 - 1 . 95 ( m , 2h ), 1 . 68 ( m , 1h ), 1 . 38 ( ddd , j = 14 . 1 , 9 . 8 , 4 . 9 hz , 1h ), 1 . 31 ( d , j = 6 . 8 hz , 3h ), 1 . 04 ( d , j = 6 . 9 hz , 3h ), 0 . 98 ( s , 9h ), 0 . 95 ( d , j = 6 . 7 hz , 3h ), 0 . 14 ( s , 3h ), 0 . 13 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 176 . 8 , 158 . 8 , 152 . 8 , 135 . 1 , 130 . 8 , 129 . 3 , 128 . 9 , 128 . 7 , 127 . 1 , 113 . 5 , 77 . 6 , 72 . 6 , 72 . 4 , 65 . 7 , 55 . 0 , 38 . 9 , 38 . 0 , 37 . 6 , 35 . 3 , 33 . 8 , 26 . 0 , 18 . 8 , 18 . 3 , 14 . 9 , 13 . 8 , − 3 . 8 , − 4 . 2 . n - buli ( 2 . 5 m in hexane , 17 . 6 ml , 44 mmol ) was added to a solution of diisopropylamine ( 6 . 65 ml , 47 . 4 mmol ) in thf ( 48 ml ) stirred at − 78 ° c . the solution was stirred at − 78 ° c . for 5 min and warmed to 0 ° c . for 15 min . borane - ammonia complex ( 90 %, 1 . 55 g , 45 . 2 mmol ) was added and the resulting mixture was stirred at 0 ° c . for 15 min , warmed to room temperature for 15 min and then cooled to 0 ° c . a solution of amide 26 ( 6 . 62 g , 11 . 3 mmol ) in thf ( 35 ml ) was added dropwise and the reaction was stirred at 0 ° c . for 1 h and then at room temperature for 2 h . the mixture was cooled to 0 ° c . and quenched carefully with saturated aqueous nh 4 cl . the mixture was extracted with et 2 o and the combined organic extracts were washed with brine , dried over mgso 4 , filtered and concentrated under reduced pressure . the residue was purified by flash chromatography ( step gradient of 4 : 1 to 7 : 3 hexane / etoac ) to afford the alcohol 27 ( 4 . 57 g , 96 %) as a colorless oil : ir ( film ) 3410 , 1612 , 1513 , 1249 , 1067 , 1038 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 26 ( d , j = 8 . 6 hz , 2h ), 6 . 88 ( d , j = 8 . 6 hz , 2h ), 4 . 44 ( d , j = 11 . 7 hz , 1h ), 4 . 39 ( d , j = 11 . 7 hz , 1h ), 3 . 81 ( s , 3h ), 3 . 51 ( m , 2h ), 3 . 44 ( dd , j = 5 . 6 , 3 . 4 hz , 1h ), 3 . 37 ( dd , j = 10 . 6 , 6 . 5 hz , 1h ), 3 . 22 ( dd , j = 9 . 0 , 7 . 0 hz , 1h ), 2 . 03 - 1 . 95 ( m , 1h ), 1 . 78 - 1 . 62 ( m , 2h ), 1 . 53 ( br , 1h ), 1 . 41 ( ddd , j = 13 . 5 , 7 . 5 , 5 . 8 hz , 1h ), 0 . 95 ( d , j = 6 . 9 hz , 3h ), 0 . 94 ( d , j = 6 . 7 hz , 3h ), 0 . 88 ( s , 9h ), 0 . 87 ( d , j = 6 . 9 hz , 3h ), 0 . 04 ( s , 3h ), 0 . 03 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 130 . 9 , 129 . 4 , 113 . 9 , 77 . 5 , 72 . 8 , 67 . 7 , 55 . 4 , 38 . 3 , 38 . 0 , 33 . 6 , 33 . 2 , 26 . 3 , 18 . 6 , 18 . 0 , 15 . 6 , 15 . 5 , − 3 . 5 , − 3 . 8 ; [ α ] 20 d − 6 . 3 ( c 1 . 7 , chcl 3 ). tbscl ( 4 . 16 g , 27 . 6 mmol ) was added to a solution of alcohol 27 ( 5 . 86 g , 13 . 8 mmol ), imidazole ( 2 . 89 g , 41 . 4 mmol ), and dmap ( 169 mg , 1 . 38 mmol ) in ch 2 cl 2 ( 55 ml ). the resulting white suspension was stirred at room temperature for 2 h and the volatiles were removed under reduced pressure . the residue was dissolved in hexane and brine . the phases were separated and the organic layer was washed with brine , dried over mgso 4 , filtered and concentrated under reduced pressure . the residue was purified by flash chromatography ( hexane / etoac 19 : 1 ) to afford the tbs protected alcohol ( 7 . 04 g , 95 %) as a colorless oil : ir ( film ) 1513 , 1471 , 1463 , 1249 , 1091 , 1039 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 30 ( d , j = 8 . 6 hz , 2h ), 6 . 91 ( d , j = 8 . 6 hz , 2h ), 4 . 48 ( d , j = 11 . 9 hz , 1h ), 4 . 44 ( d , j = 11 . 9 hz , 1h ), 3 . 82 ( s , 3h ), 3 . 60 - 3 . 49 ( m , 3h ), 3 . 39 - 3 . 28 ( m , 3h ), 2 . 05 - 1 . 95 ( m , 1h ), 1 . 80 - 1 . 66 ( m , 2h ), 1 . 49 - 1 . 40 ( m , 2h ), 1 . 02 ( d , j = 6 . 9 hz , 3h ), 1 . 0 - 0 . 91 ( m , 24 h ), 0 . 10 ( s , 3h ), 0 . 09 ( s , 3h ), 0 . 08 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 131 . 1 , 129 . 3 , 127 . 9 , 77 . 3 , 73 . 1 , 72 . 8 , 68 . 4 , 55 . 3 , 38 . 9 , 38 . 5 , 33 . 5 , 26 . 4 , 26 . 2 , 18 . 7 , 18 . 6 , 18 . 1 , 15 . 3 , 15 . 1 , − 3 . 4 , − 3 . 8 , − 5 . 2 ; [ a ] 20 d − 15 . 9 ( c 0 . 47 , chcl 3 ). a solution of above tbs protected alcohol ( 5 . 28 g , 9 . 8 mmol ) in ch 2 cl 2 ( 332 ml ) and ph 7 phosphate buffer solution ( 33 ml ) was treated with ddq ( 3 . 34 g , 14 . 7 mmol ). the reaction was stirred at room temperature for 1 h and was quenched with saturated aqueous nahco 3 solution . the phases were separated and the aqueous layer was extracted with ch 2 cl 2 . the combined organic extracts were washed with water , dried over mgso 4 , filtered , and concentrated under reduced pressure . the residue was purified by flash chromatography ( hexane / etoac 97 : 3 to 93 : 7 ) to afford 28 ( 4 . 01 g , 98 %) as a colorless oil : ir ( film ) 3353 , 1472 , 1463 , 1388 , 1360 , 1255 , 1091 , 1030 , 1005 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 3 . 60 ( d , j = 5 . 3 hz , 2h ), 3 . 55 - 3 . 45 ( m , 2h ), 3 . 32 ( dd , j = 9 . 7 , 6 . 7 hz , 1h ), 2 . 49 ( br , 1h ), 1 . 45 ( ddd , j = 13 . 5 , 7 . 5 , 5 . 3 hz , 1h ), 0 . 95 ( d , j = 7 . 1 hz , 3h ), 0 . 92 ( s , 9h ), 0 . 89 ( s , 9h ), 0 . 93 - 0 . 87 ( m , 6h ), 0 . 11 ( s , 3h ), 0 . 09 ( s , 3h ), 0 . 04 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 80 . 9 , 68 . 0 , 66 . 2 , 38 . 4 , 37 . 8 , 35 . 4 , 33 . 5 , 26 . 3 , 26 . 1 , 18 . 5 , 18 . 3 , 16 . 2 , 15 . 7 , − 3 . 6 , − 3 . 9 , − 5 . 3 ; [ α ] 20 d − 16 . 1 ( c 4 . 4 , chcl 3 ). sulfur trioxide pyridine complex ( 5 . 44 g , 34 . 2 mmol ) was added to a solution of 28 ( 4 . 78 g , 11 . 4 mmol ) and triethylamine ( 4 . 77 ml , 34 . 2 mmol ) in ch 2 cl 2 ( 23 ml ) and dmso ( 46 ml ) at 0 ° c . the mixture was stirred at 0 ° c . for 1 h and then diluted with et 2 o . the organic phase was washed with cold 0 . 5 m aqueous nahso 4 and then with brine . the organic layer was dried over mgso 4 , filtered and concentrated under reduced pressure . the residue was purified by short flash chromatography ( hexane / etoac 9 : 1 ) to afford the crude aldehyde as a golden oil which was used directly in the next reaction without further purification . carbon tetrabromide ( 7 . 56 g , 22 . 8 mmol ) was added to a solution of triphenylphosphine ( 12 . 3 g , 45 . 6 mmol ) in ch 2 cl 2 ( 56 ml ) at 0 ° c . the resulting dark - red mixture was stirred at 0 ° c . for 10 min . a solution of the crude aldehyde and 2 , 6 - lutidine ( 2 . 66 ml , 22 . 8 mmol ) in ch 2 cl 2 ( 45 ml ) was added dropwise . the dark - brown mixture was stirred at 0 ° c . for 1 h and then quenched with a saturated aqueous nh 4 cl . the layers were separated and the aqueous phase was extracted with ch 2 cl 2 . the combined organic extracts were washed with h 2 o , dried over mgso 4 , filtered and concentrated under reduced pressure . the residue was purified by short flash chromatography ( hexane 100 %) to afford the dibromoolefin ( 4 . 76 g , 73 % yield from the alcohol ) as a colorless oil that was used without further purification . a solution of the dibromoolefin ( 4 . 76 g , 8 . 2 mmol ) in thf ( 40 ml ) stirred at − 78 ° c . was treated with n - buli ( 1 . 6 m in hexane , 15 . 4 ml , 24 . 6 mmol ). the solution was stirred at − 78 ° c . for 2 h and then quenched with saturated aqueous nh 4 cl . the mixture was allowed to reach room temperature and was diluted with et 2 o . the aqueous layer was extracted with et 2 o . the combined organic extracts were washed with brine , dried over mgso 4 , filtered and concentrated under reduced pressure . the residue was purified by flash chromatography ( hexane : etoac 97 : 3 ) to afford the pure alkyne 29 ( 3 . 26 g , 95 %) as a colorless oil : ir ( film ) 3313 , 2100 , 1472 , 1463 , 1252 , 1088 , 1005 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 3 . 53 - 3 . 48 ( m , 2h ), 3 . 33 ( d , j = 9 . 7 , 6 . 8 hz , 1h ), 2 . 62 ( ddddd , j = 7 . 2 , 7 . 2 , 7 . 2 , 5 . 1 , 2 . 5 hz , 1h ), 2 . 03 ( d , j = 2 . 5 hz , 1h ), 1 . 97 - 1 . 80 ( m , 1h ), 1 . 73 - 1 . 6 ( m , 1h ), 1 . 47 ( m , 1h ), 1 . 21 ( d , j = 7 . 1 hz , 3h ), 0 . 99 - 0 . 91 ( m , 6h ), 0 . 95 ( s , 9h ), 0 . 93 ( s , 9h ), 0 . 13 ( s , 3h ), 0 . 11 ( s , 3h ), 0 . 08 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 87 . 9 , 77 . 8 , 70 . 2 , 68 . 5 , 39 . 2 , 33 . 9 , 33 . 7 , 32 . 3 , 26 . 4 , 26 . 3 , 18 . 6 , 17 . 9 , 17 . 5 , 15 . 7 , − 3 . 6 , − 5 . 1 ; hrms ( esi ) calcd for c 22 h 45 o 2 si 2 na 397 . 2958 [ m + na ] + , found 397 . 2950 ; [ α ] 20 d − 8 . 2 ( c 3 . 1 , chcl 3 ). pph 3 ( 7 . 05 g , 26 . 2 mmol ), imidazole ( 1 . 78 g , 26 . 2 mmol ), diisopropylethylamine ( 4 . 6 ml , 26 . 2 mmol ) in benzene ( 80 ml ), diethyl ether ( 165 ml ) and acetonitrile ( 33 ml ) were stirred at room temperature and treated with iodine ( 6 . 65 g , 26 . 2 mmol ). the resulting mixture was vigorously stirred until the formation of a beige suspension . a solution of the alcohol 21 ( 5 . 0 g , 13 . 1 mmol ) in et 2 o ( 20 ml ) was added dropwise to the suspension and the resulting mixture was stirred at room temperature for 30 min . the reaction was quenched with saturated aqueous nahco 3 and diluted with et 2 o . the aqueous phase was extracted with et 2 o and the combined organic extracts were washed with brine , dried over mgso 4 , filtered and concentrated under reduced pressure . the residue was triturated with hexane and the triturate was concentrated under reduced pressure . this procedure was repeated two more times to afford the iodide as a colorless oil that was used directly in the next reaction . a solution of n - buli in hexane ( 2 . 5 m , 21 ml , 52 . 4 mmol ) was added to a suspension of licl ( 7 . 05 g , 166 . 4 mmol ) and diisopropylamine ( 7 . 85 ml , 56 . 3 mmol ) in thf ( 40 ml ) at − 78 ° c . the suspension was stirred at − 78 ° c . for 5 min , 0 ° c . for 15 min and then cooled to − 78 ° c . a solution of ( s , s )- pseudoephedrine propionamide ( meyer &# 39 ; s auxiliary , 30 ) ( 6 . 09 g , 27 . 5 mmol ) in thf ( 70 ml ) was added dropwise . the resulting mixture was stirred at − 78 ° c . for 1 h , at 0 ° c . for 15 min and at room temperature for 5 min . the suspension was cooled to 0 ° c . and the iodide was added as a solution in thf ( 6 ml followed by a 6 ml rinse ). the reaction mixture was stirred at room temperature for 24 h and quenched with half - saturated aqueous nh 4 cl . the aqueous layer was extracted with etoac and the combined organic extracts were dried over na 2 so 4 , filtered and concentrated under reduced pressure to give a residue which was purified by flash chromatography ( hexane / etoac 1 : 1 ) to afford the amide 31 ( 6 . 69 g , 87 %) as a colorless oil : ir ( film ) 3387 , 1616 , 1513 , 1463 , 1248 , 1087 , 1037 cm − 1 ; hrms ( esi ) calcd for c 34 h 56 no 5 si 586 . 3928 , found 586 . 3940 ; [ α ] 20 d + 23 . 2 ( c 1 . 26 , chcl 3 ). alkyne 29 ( 4 . 12 g , 10 . 0 mmol ) was dissolved in thf ( 100 ml ) and cooled to − 78 ° c . n - buli ( 6 . 25 ml , 1 . 6 m hexane solution ) was added slowly . after 5 min , the mixture was warmed to 0 ° c . and stirred for 30 min . the mixture was then cooled to − 78 ° c . and amide 15 ( 6 . 47 g , 11 . 3 mmol ) in thf ( 5 ml ) was added slowly . after 5 min , the solution was warmed to 0 ° c . and stirred for 30 min . the reaction was quenched with saturated aqueous nh 4 cl and the mixture was partitioned in a separatory funnel . the aqueous phase was extracted with et 2 o ( 3 × 20 ml ). the combined organic extracts were washed with brine and dried over mgso 4 . filtration and concentration under reduced pressure , followed by flash chromatography on silica gel ( hexane / etoac 19 : 1 ), afforded the ynone 32 ( 9 . 70 g , 93 %) as a pale yellow oil : ir ( chcl 3 ) 2955 , 2928 , 2856 , 2209 , 1676 , 1471 , 1462 , 1252 , 1085 , 836 , 774 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 56 m , 6h ), 7 . 36 ( m , 9h ), 5 . 80 ( dd , j = 15 . 6 , 7 . 1 hz , 1h ), 5 . 69 ( dt , j = 15 . 7 , 4 . 8 hz , 1h ), 4 . 37 ( m , 1h ), 3 . 69 ( d , j = 4 . 7 hz , 2h ), 3 . 61 ( m , 1h ), 3 . 58 ( dd , j = 9 . 7 , 5 . 0 hz , 1h ), 3 . 43 ( dd , j = 9 . 7 , 6 . 5 hz , 1h ), 2 . 87 ( m , 1h ), 2 . 73 ( m , 1h ), 2 . 46 ( m , 1h ), 1 . 88 ( m , 1h ), 1 . 76 ( m , 1h ), 1 . 59 ( m , 1h ), 1 . 31 ( d , j = 7 . 1 hz , 3h ), 1 . 15 ( d , j = 6 . 8 hz , 3h ), 1 . 05 ( m , 1h ), 1 . 00 ( m , 3h ), 0 . 194 ( s , 3h ), 0 . 190 ( s , 3h ), 0 . 17 ( s , 3h ), 0 . 15 ( s , 3h ), 0 . 14 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 186 . 1 , 144 . 2 , 132 . 9 , 128 . 6 , 127 . 7 , 126 . 9 , 96 . 8 , 86 . 8 , 83 . 1 , 71 . 5 , 68 . 0 , 64 . 9 , 50 . 0 , 42 . 3 , 38 . 1 , 34 . 4 , 33 . 2 , 32 . 1 , 26 . 01 , 25 . 96 , 25 . 85 , 18 . 3 , 18 . 0 , 17 . 9 , 17 . 2 , 15 . 5 , 15 . 4 , − 3 . 8 , − 4 . 1 , − 4 . 6 , − 4 . 7 , − 5 . 4 ; lrms ( esi ) 947 . 5 [ m + na ]+, 562 . 3 , 243 . 1 ; hrms ( esi ) calcd for c 56 h 88 o 5 si 3 na 947 . 5837 [ m + na ] + , found 947 . 5875 ; [ α ] 20 d − 12 . 0 ( c 0 . 54 , chcl 3 ). ynone 32 ( 5 . 28 g , 5 . 71 mmol ) was taken up in i - proh ( 58 ml ). the ( s , s )- noyori catalyst ( 0 . 77 g , 1 . 15 mmol , 20 mol %) was added in one portion and the solution was stirred overnight . the solvent was removed under vacuum , and the crude residue was purified by flash chromatography on silica gel ( hexane / etoac 97 : 3 ), affording propargylic alcohol 33 ( 4 . 18 g , 79 %) as a pale yellow oil : ir ( chcl 3 ) 3469 , 2955 , 2856 , 1471 , 1448 , 1252 , 1084 , 836 , 774 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 55 ( m , 6h ), 7 . 36 ( m , 9h ), 5 . 71 ( m , 2h ), 4 . 59 ( m , 1h ), 4 . 03 ( quint , j = 3 . 9 hz , 1h ), 3 . 65 ( d , j = 3 . 9 hz , 2h ), 3 . 58 ( dd , j = 4 . 6 , 3 . 2 hz , 1h ), 3 . 55 ( dd , j = 10 . 1 , 5 . 1 hz , 1h ), 3 . 38 ( dd , j = 9 . 7 , 6 . 8 hz , 1h ), 2 . 71 ( m , 1h ), 2 . 50 ( m , 1h ), 2 . 32 ( d , j = 5 . 4 hz , 1h ), 1 . 88 ( m , 1h ), 1 . 80 ( m , 2h ), 1 . 55 ( m , 1h ), 1 . 23 ( d , j = 7 . 1 hz , 3h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 0 . 98 ( m , 34h ), 0 . 20 ( s , 3h ), 0 . 17 ( s , 3h ), 0 . 16 ( s , 3h ), 0 . 14 ( s , 3h ), 0 . 12 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 3 , 134 . 0 , 128 . 6 , 127 . 8 , 127 . 1 , 126 . 9 , 88 . 1 , 86 . 8 , 83 . 0 , 72 . 6 , 68 . 3 , 65 . 8 , 65 . 1 , 59 . 5 , 41 . 9 , 40 . 3 , 38 . 7 , 33 . 5 , 33 . 2 , 32 . 1 , 26 . 0 , 25 . 9 , 18 . 4 , 18 . 1 , 17 . 7 , 17 . 4 , 15 . 7 , 15 . 3 , 14 . 2 , − 3 . 9 , − 4 . 0 , − 4 . 4 , − 4 . 5 , − 5 . 3 ; lrms ( esi ) 949 . 7 [ m + na ]+, 413 . 3 , 243 . 1 ; hrms ( esi ) calcd for c 56 h 90 o 5 si 3 na 949 . 5994 [ m + na ] + , found 949 . 6018 ; [ α ] 20 d − 10 . 0 ( c 1 . 2 , chcl 3 ). a catalytic amount of lindlar catalyst ( ca . 200 mg ) was added to a solution of alcohol 33 ( 4 . 18 g , 4 . 51 mmol ) in toluene ( 100 ml ). the flask was flushed with h 2 via a balloon several times , then stirred under an atmosphere of h 2 until starting material was consumed ( usually 1 h ) as indicated by tlc analysis . the mixture was filtered through a pad of celite and concentrated under reduced pressure to afford the alkene 34 as a colorless oil ( 3 . 82 g , 91 %): ir ( chcl 3 ) 3436 , 2954 , 2926 , 2855 , 1461 , 1378 , 1252 , 1061 , 836 , 773 cm − 11 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 56 ( m , 6h ), 7 . 34 ( m , 9h ), 5 . 73 ( m , 2h ), 5 . 60 ( t , j = 10 . 3 hz , 1h ), 5 . 43 ( dd , j = 10 . 9 , 8 . 4 hz , 1h ), 4 . 73 ( m , 1h ), 3 . 98 ( q , j = 5 . 0 hz , 1h ), 3 . 68 ( d , j = 4 . 1 hz , 1h ), 3 . 59 ( dd , j = 9 . 7 , 4 . 7 hz , 1h ), 3 . 48 ( m , 1h ), 3 . 36 ( dd , j = 9 . 0 , 7 . 3 hz , 1h ), 2 . 79 ( m , 1h ), 2 . 58 ( m , 1h ), 2 . 23 ( br , 1h ), 1 . 78 ( m , 1h ), 1 . 71 ( m , 1h ), 1 . 66 ( m , 2h ), 1 . 50 ( m , 1h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 1 . 07 ( d , j = 6 . 8 hz , 3h ), 1 . 00 ( m , 34h ), 0 . 22 ( s , 3h ), 0 . 18 ( s , 3h ), 0 . 14 ( s , 6h ), 0 . 13 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 3 , 135 . 3 , 134 . 6 , 131 . 5 , 128 . 7 , 127 . 7 , 127 . 0 , 126 . 8 , 86 . 8 , 79 . 6 , 73 . 0 , 68 . 2 , 65 . 0 , 64 . 7 , 42 . 0 , 39 . 6 , 38 . 0 , 36 . 4 , 34 . 9 , 33 . 4 , 26 . 2 , 26 . 0 , 25 . 9 , 19 . 9 , 18 . 4 , 18 . 3 , 18 . 1 , 18 . 0 , 15 . 2 , 14 . 5 , − 3 . 4 , − 3 . 7 , − 4 . 2 , − 4 . 4 , − 4 . 5 , − 5 . 4 ; lrms ( esi ) 951 . 7 [ m + na ] + , 413 . 3 , 243 . 1 ; hrms ( esi ) calcd for c 56 h 92 o 5 si 3 na 951 . 6150 [ m + na ] + , found 951 . 6172 ; [ α ] 20 d 1 . 0 ( c 0 . 62 , chcl 3 ). tbsotf ( 2 . 08 ml , 9 . 07 mmol ) was added to a stirred solution of the alcohol 34 ( 3 . 82 g , 4 . 11 mmol ) and 2 , 6 - lutidine ( 1 . 14 ml , 9 . 85 mmol ) in ch 2 cl 2 ( 14 ml ) at 0 ° c . the reaction mixture was stirred for 1 h at 0 ° c . the reaction mixture was quenched by the addition of h 2 o ( 25 ml ). the reaction mixture was extracted with ch 2 cl 2 which was dried over mgso 4 , filtered and the solvent was evaporated under reduced pressure . the residue was purified by short column chromatography ( hexane / etoac 19 : 1 ) to obtain 35 ( 4 . 27 g , 99 %) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2856 , 1471 , 1462 , 1449 , 1255 , 1089 , 1005 , 836 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 60 ( m , 6h ), 7 . 39 ( m , 9h ), 5 . 77 ( m , 2h ), 5 . 56 ( t , j = 10 . 8 hz , 1h ), 5 . 42 ( dd , j = 11 . 0 , 8 . 2 hz , 1h ), 4 . 69 ( m , 1h ), 4 . 07 ( m , 1h ), 3 . 71 ( d , j = 3 . 8 hz , 2h ), 3 . 64 ( dd , j = 9 . 8 , 4 . 8 hz , 1h ), 3 . 53 ( m , 1h ), 3 . 40 ( dd , j = 9 . 6 , 7 . 5 hz , 1h ), 2 . 74 ( m , 1h ), 2 . 55 ( m , 1h ), 1 . 89 ( m , 3h ), 1 . 59 ( m , 3h ), 1 . 12 ( d , j = 6 . 2 hz , 6h ), 1 . 04 ( m , 42h ), 0 . 26 ( s , 3h ), 0 . 24 ( s , 3h ), 0 . 19 ( s , 6h ), 0 . 18 ( s , 3h ), 0 . 17 ( s , 6h ), 0 . 16 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 4 , 134 . 5 , 132 . 9 , 132 . 6 , 128 . 7 , 127 . 7 , 126 . 8 , 86 . 8 , 79 . 9 , 72 . 3 , 68 . 3 , 66 . 5 , 65 . 1 , 64 . 1 , 42 . 4 , 41 . 6 , 37 . 9 , 36 . 0 , 35 . 3 , 33 . 6 , 26 . 3 , 26 . 02 , 25 . 97 , 25 . 7 , 19 . 4 , 18 . 5 , 18 . 4 , 18 . 20 , 18 . 15 , 18 . 1 , 15 . 5 , 13 . 3 , − 2 . 9 , − 3 . 5 , − 3 . 7 , − 4 . 1 , − 4 . 2 , − 4 . 3 , − 5 . 3 ; lrms ( esi ) 1065 . 9 [ m + na ] + , 413 . 3 , 359 . 3 , 328 . 3 , 243 . 1 ; hrms ( esi ) calcd for c 62 h 106 o 5 si 4 na 1065 . 7015 [ m + na ] + , found 1065 . 7026 ; [ α ] 20 d − 10 . 4 ( c 0 . 53 , chcl 3 ). hf - pyridine in pyridine ( 40 ml , prepared by slow addition of 12 ml pyridine to 3 ml hf - pyridine complex followed by dilution with 25 ml thf ) was slowly added to a solution of tbs ether 35 ( 4 . 27 g , 4 . 10 mmol ) in thf ( 5 ml ) at 0 ° c . the mixture was stirred for 21 h at 0 ° c . and quenched with saturated aqueous nahco 3 ( 100 ml ). the aqueous layer was separated and extracted with et 2 o ( 3 × 50 ml ). the combined organic layers were washed with saturated aqueous cuso 4 ( 3 × 50 ml ), dried over mgso 4 , filtered and concentrated . flash column chromatography ( etoac / hexane 1 : 4 ) afforded 2 . 55 g ( 67 %) of the alcohol 36 as a colorless oil : ir ( chcl 3 ) 3350 , 2956 , 2928 , 2856 , 1471 , 1448 , 1254 , 1086 , 836 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 52 ( m , 6h ), 7 . 32 ( m , 9h ), 5 . 68 ( m , 2h ), 5 . 50 ( t , j = 10 . 6 hz , 1h ), 5 . 35 ( dd , j = 10 . 9 , 8 . 5 hz , 1h ), 4 . 61 ( t , j = 8 . 5 hz , 1h ), 4 . 00 ( t , j = 8 . 1 hz , 1h ), 3 . 62 ( d , j = 3 . 2 hz , 2h ), 3 . 58 ( dd , j = 10 . 6 , 4 . 3 hz , 1h ), 3 . 45 ( m , 1h ), 3 . 36 ( dd , j = 9 . 9 , 7 . 3 hz , 1h ), 2 . 66 ( m , 1h ), 2 . 48 ( m , 1h ), 1 . 70 ( m , 3h ), 1 . 49 ( m , 3h ), 1 . 04 ( d , j = 6 . 6 hz , 6h ), 0 . 97 ( s , 18h ), 0 . 93 ( m , 6h ), 0 . 87 ( s , 9h ), 0 . 18 ( s , 3h ), 0 . 16 ( s , 3h ), 0 . 11 ( s , 6h ), 0 . 10 ( s , 3h ), 0 . 08 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 3 , 134 . 4 , 133 . 0 , 132 . 1 , 128 . 7 , 127 . 7 , 126 . 8 , 86 . 7 , 79 . 8 , 72 . 3 , 67 . 7 , 66 . 5 , 65 . 1 , 42 . 4 , 41 . 5 , 37 . 3 , 35 . 7 , 35 . 5 , 33 . 3 , 26 . 2 , 26 . 0 , 25 . 9 , 19 . 6 , 18 . 4 , 18 . 14 , 18 . 06 , 17 . 98 , 15 . 7 , 13 . 2 , − 2 . 9 , − 3 . 6 , − 3 . 7 , − 4 . 1 , − 4 . 2 , − 4 . 3 ; lrms ( esi ) 951 . 8 [ m + na ] + , 771 . 6 , 328 . 3 ; hrms ( esi ) calcd for c 56 h 92 o 5 si 3 na 951 . 6150 [ m + na ] + , found 951 . 6162 ; [ α ] 20 d − 12 . 0 ( c 0 . 71 , chcl 3 ). the alcohol 36 ( 2 . 55 g , 2 . 75 μmol ) in ch 2 cl 2 ( 30 ml ) was treated with dess - martin periodinane ( 1 . 74 g , 4 . 10 μmol ). after 1 h , the mixture was quenched with saturated aqueous nahco 3 ( 30 ml ) and na 2 s 2 o 3 ( 30 ml ). the aqueous layer was extracted with et 2 o ( 2 × 30 ml ) and the combined extracts were dried over anhydrous mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 4 : 1 ) provided the crude aldehyde as a colorless oil , which was used without further purification . a mixture of ketophosphonate 38 ( 1 . 06 g , 2 . 75 mmol ) and ba ( oh ) 2 ( 0 . 38 g , activated by heating to 100 ° c . for 1 - 2 h before use ) in thf ( 40 ml ) was stirred at room temperature for 30 min . a solution of the above aldehyde in wet thf ( 4 × 1 ml washings , 40 : 1 thf / h 2 o ) was then added . after stirring for 12 h , the reaction mixture was diluted with et 2 o ( 30 ml ) and washed with saturated aqueous nahco 3 ( 50 ml ) and brine ( 50 ml ). the organic solution was dried ( mgso 4 ), filtered and the solvent was evaporated in vacuo . the residue was chromatographed ( hexane / etoac 9 : 1 ) to yield 39 ( 2 . 60 g , 80 % for 2 steps ) as a colorless oil : ir ( chcl 3 ) 2956 , 2928 , 2855 , 1688 , 1618 , 1518 , 1471 , 1461 , 1338 , 1251 , 1080 , 1038 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 50 ( m , 6h ), 7 . 40 ( m , 2h ), 7 . 30 ( m , 9h ), 6 . 89 ( m , 2h ), 6 . 73 ( dd , j = 15 . 6 , 8 . 5 hz , 1h ), 6 . 29 ( d , j = 15 . 6 hz , 1h ), 5 . 66 ( m , 2h ), 5 . 46 ( t , j = 10 . 4 hz , 1h ), 5 . 46 ( s , 1h ), 5 . 31 ( dd , j = 11 . 0 , 8 . 4 hz , 1h ), 4 . 58 ( t , j = 8 . 1 hz , 1h ), 4 . 12 ( dd , j = 11 . 3 , 4 . 6 hz , 1h ), 3 . 96 ( m , 1h ), 3 . 92 ( dd , j = 10 . 0 , 4 . 2 hz , 1h ), 3 . 80 ( s , 3h ), 3 . 60 ( d , j = 2 . 8 hz , 2h ), 3 . 56 ( m , 1h ), 3 . 39 ( t , j = 3 . 3 hz , 1h ), 2 . 93 ( m , 1h ), 2 . 64 ( m , 1h ), 2 . 45 ( m , 1h ), 2 . 37 ( m , 1h ), 2 . 01 ( m , 1h ), 1 . 61 ( m , 1h ), 1 . 54 ( m , 2h ), 1 . 50 ( m , 1h ), 1 . 44 ( m , 1h ), 1 . 27 ( d , j = 7 . 0 hz , 3h ), 1 . 06 ( d , j = 6 . 6 hz , 3h ), 1 . 02 ( d , j = 6 . 5 hz , 3h ), 0 . 99 ( d , j = 6 . 6 hz , 3h ), 0 . 95 ( s , 9h ), 0 . 94 ( s , 9h ), 0 . 88 ( d , j = 6 . 6 hz , 3h ), 0 . 84 ( s , 9h ), 0 . 79 ( d , j = 6 . 7 hz , 3h ), 0 . 15 ( s , 3h ), 0 . 14 ( s , 3h ), 0 . 07 ( s , 3h ), 0 . 06 ( s , 3h ), 0 . 05 ( s , 3h ), 0 . 03 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 200 . 7 , 159 . 8 , 152 . 3 , 144 . 3 , 134 . 3 , 132 . 8 , 132 . 1 , 131 . 0 , 128 . 6 , 127 . 7 , 127 . 1 , 126 . 8 , 126 . 6 , 113 . 4 , 100 . 8 , 86 . 7 , 82 . 7 , 80 . 0 , 72 . 8 , 72 . 1 , 66 . 4 , 65 . 0 , 55 . 2 , 47 . 1 , 42 . 4 , 41 . 4 , 39 . 3 , 35 . 8 , 34 . 7 , 34 . 6 , 32 . 2 , 26 . 1 , 25 . 92 , 25 . 86 , 20 . 8 , 19 . 7 , 18 . 3 , 18 . 1 , 18 . 0 , 15 . 0 , 13 . 0 , 12 . 4 , 10 . 8 , − 2 . 9 , − 3 . 7 , − 3 . 8 , − 4 . 18 , − 4 . 25 , − 4 . 35 ; lrms ( esi ) 1209 . 6 [ m + na ] + , 828 . 4 , 715 . 3 , 449 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 72 h 110 o 8 si 3 na 1209 . 7406 [ m + na ] + , found 1209 . 7474 ; [ α ] 20 d − 6 . 7 ( c 0 . 11 , chcl 3 ). nicl 2 . 6h 2 o ( 0 . 26 g , 1 . 09 mmol ) then portionwise nabh 4 ( 0 . 17 g , 4 . 49 mmol ) were added to a stirred solution of unsaturated ketone 39 ( 2 . 60 g , 2 . 19 μmol ) in 80 ml of 3 : 2 meoh / thf at 0 ° c . after 1 h , the reaction mixture was evaporated and filtered through celite using et 2 o ( 30 ml ) as an eluent . the organic phase was concentrated and the residue was purified by flash chromatography ( etoac / hexane 1 : 9 ) to yield 1 . 98 g of 40 ( 76 %) as a colorless oil : ir ( chcl 3 ) 2955 , 2927 , 2855 , 1711 , 1614 , 1518 , 1461 , 1251 , 1076 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 46 ( m , 6h ), 7 . 27 ( m , 1h ), 6 . 85 ( m , 2h ), 5 . 60 ( m , 2h ), 5 . 43 ( s , 1h ), 5 . 40 ( m , 1h ), 5 . 27 ( m , 1h ), 4 . 52 ( m , 1h ), 4 . 11 ( dd , j = 11 . 1 , 4 . 7 hz , 1h ), 3 . 91 ( m , 2h ), 3 . 78 ( s , 3h ), 3 . 55 ( m 2h ), 3 . 50 ( m , 1h ), 3 . 35 ( m , 1h ), 2 . 67 ( m , 1h ), 2 . 58 ( m , 1h ), 2 . 51 ( m , 1h ), 2 . 41 ( m , 1h ), 2 . 01 ( m , 1h ), 1 . 68 ( m , 3h ), 1 . 41 ( m , 5h ), 1 . 23 ( d , j = 7 . 1 hz , 3h ), 0 . 96 ( d , j = 6 . 7 hz , 3h ), 0 . 90 ( s , 9h ), 0 . 89 ( s , 9h ), 0 . 88 ( m , 1h ), 0 . 87 ( m , 3h ), 0 . 80 ( s , 9h ), 0 . 78 ( m , 6h ), 0 . 10 ( s , 3h ), 0 . 08 ( s , 3h ), 0 . 04 ( s , 3h ), 0 . 03 ( s , 6h ), 0 . 01 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 211 . 9 , 159 . 8 , 144 . 5 , 144 . 3 , 134 . 4 , 132 . 9 , 132 . 4 , 130 . 9 , 128 . 6 , 127 . 9 , 127 . 8 , 127 . 7 , 127 . 1 , 126 . 8 , 113 . 4 , 100 . 8 , 86 . 7 , 83 . 1 , 79 . 9 , 72 . 8 , 72 . 2 , 66 . 4 , 65 . 1 , 55 . 1 , 48 . 3 , 42 . 3 , 41 . 5 , 41 . 2 , 38 . 1 , 35 . 7 , 35 . 0 , 31 . 2 , 29 . 8 , 29 . 7 , 26 . 2 , 25 . 92 , 25 . 87 , 20 . 2 , 19 . 4 , 18 . 4 , 18 . 1 , 18 . 0 , 15 . 2 , 13 . 2 , 12 . 1 , 9 . 6 , − 3 . 0 , − 3 . 5 , − 3 . 7 , − 4 . 2 , − 4 . 28 , − 4 . 34 ; lrms ( esi ) 1211 . 9 ( 30 ml ), 1031 . 8 , 870 . 4 , 684 . 3 , 366 . 4 , 243 . 1 ; hrms ( esi ) calcd for c 72 h 112 o 8 si 3 na 1211 . 7563 ( 30 ml ), found 1211 . 7616 ; [ α ] 20 d + 1 . 6 ( c 0 . 50 , chcl 3 ). nabh 4 ( 0 . 095 g , 2 . 51 mmol ) was added to a solution of ketone 40 ( 1 . 98 g , 1 . 67 mmol ) in meoh ( 28 ml ) at 0 ° c . after stirring for 2 h at 0 ° c ., the reaction mixture was evaporated and water ( 30 ml ) was added . the reaction mixture was extracted with ether ( 2 × 40 ml ) and washed with brine ( 50 ml ), dried over mgso 4 and concentrated in vacuo . the residue was purified by flash chromatography ( etoac / hexane 1 : 9 ) to yield major product the title compound 41β ( 1 . 39 g , 70 %, less polar ) and minor product 41α ( 0 . 58 g , 28 %, more polar ) as a colorless oil . 41β : ir ( chcl 3 ) 3398 , 2954 , 2926 , 2854 , 1517 , 1460 , 1251 , 1072 , 835 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 50 ( m , 6h ), 7 . 39 ( m , 2h ), 7 . 33 ( m , 9h ), 6 . 89 ( m , 2h ), 5 . 66 ( m , 2h ), 5 . 54 ( s , 1h ), 5 . 46 ( m , 1h ), 5 . 32 ( m , 1h ), 4 . 58 ( m , 1h ), 4 . 14 ( dd , j = 11 . 3 , 4 . 6 hz , 1h ), 3 . 95 ( m , 1h ), 3 . 87 ( m , 1h ), 3 . 80 ( s , 3h ), 3 . 72 ( d , j = 9 . 8 hz , 1h ), 3 . 61 ( m , 2h ), 3 . 55 ( m , 1h ), 3 . 41 ( m , 1h ), 3 . 24 ( br , 1h ), 2 . 64 ( m , 1h ), 2 . 46 ( m , 1h ), 2 . 16 ( m , 1h ), 1 . 82 ( m , 1h ), 1 . 71 ( m , 2h ), 1 . 53 ( m , 5h ), 1 . 35 ( m , 2h ), 1 . 06 ( d , j = 7 . 2 hz , 3h ), 1 . 01 ( d , j = 6 . 6 hz , 3h ), 0 . 95 ( s , 9h ), 0 . 93 ( s , 9h ), 0 . 90 ( m , 9h ), 0 . 85 ( s , 9h ), 0 . 78 ( d , j = 6 . 6 hz , 3h ), 0 . 14 ( m , 6h ), 0 . 09 ( m , 12h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 160 . 0 , 144 . 5 , 144 . 3 , 134 . 4 , 132 . 9 , 132 . 4 , 130 . 7 , 128 . 7 , 127 . 9 , 127 . 8 , 127 . 7 , 127 . 6 , 127 . 2 , 127 . 1 , 126 . 8 , 113 . 6 , 101 . 2 , 89 . 1 , 86 . 7 , 80 . 0 , 76 . 9 , 73 . 1 , 72 . 2 , 66 . 5 , 65 . 1 , 42 . 3 , 41 . 5 , 41 . 4 , 37 . 0 , 36 . 7 , 35 . 1 , 32 . 5 , 32 . 1 , 30 . 4 , 30 . 3 , 26 . 2 , 25 . 93 , 25 . 87 , 20 . 4 , 19 . 4 , 18 . 4 , 18 . 1 , 18 . 0 , 15 . 4 , 13 . 2 , 11 . 8 , 5 . 4 , − 3 . 0 , − 3 . 5 , − 3 . 7 , − 4 . 2 , − 4 . 27 , − 4 . 33 ; lrms ( esi ) 1213 . 7 [ m + na ] + , 1033 . 6 , 570 . 9 , 364 . 3 , 243 . 1 ; hrms ( esi ) calcd for c 72 h 114 o 8 si 3 na 1213 . 7719 [ m + na ] + , found 1213 . 7861 ; [ α ] 20 d + 6 . 5 ( c 0 . 31 , chcl 3 ). 41α : ir ( chcl 3 ) 3540 , 2956 , 2929 , 2855 , 1615 , 1518 , 1461 , 1383 , 1251 , 1074 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 61 ( m , 6h ), 7 . 51 ( m , 2h ), 7 . 44 - 7 . 32 ( m , 9h ), 7 . 00 ( m , 2h ), 5 . 77 ( m , 2h ), 5 . 61 ( s , 1h ), 5 . 55 ( m , 1h ), 5 . 45 ( m , 1h ), 4 . 71 ( m , 1h ), 4 . 24 ( dd , j = 11 . 1 , 4 . 5 hz , 1h ), 4 . 07 ( m , 1h ), 4 . 01 ( m , 1h ), 3 . 88 ( s , 3h ), 3 . 73 - 3 . 60 ( m , 4h ), 3 . 54 ( m , 1h ), 2 . 76 ( m , 1h ), 2 . 56 ( m , 1h ), 2 . 49 ( m , 1h ), 2 . 24 ( m , 1h ), 1 . 94 - 1 . 78 ( m , 4h ), 1 . 72 - 1 . 46 ( m , 6h ), 1 . 42 - 1 . 31 ( m , 2h ), 1 . 22 ( d , j = 7 . 0 hz , 3h ), 1 . 13 ( d , j = 5 . 9 hz , 3h ), 1 . 06 ( s , 18h ), 1 . 03 ( m , 6h ), 0 . 96 ( s , 9h ), 0 . 86 ( d , j = 6 . 6 hz , 3h ), 0 . 27 - 0 . 18 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 9 , 144 . 4 , 144 . 3 , 134 . 3 , 132 . 9 , 132 . 4 , 131 . 0 , 128 . 6 , 127 . 6 , 127 . 2 , 126 . 8 , 113 . 5 , 101 . 0 , 86 . 7 , 82 . 8 , 79 . 8 , 74 . 8 , 73 . 2 , 72 . 2 , 66 . 4 , 65 . 0 , 55 . 1 , 42 . 3 , 41 . 5 , 37 . 8 , 35 . 9 , 34 . 9 , 33 . 2 , 32 . 4 , 30 . 3 , 30 . 2 , 26 . 2 , 25 . 92 , 25 . 87 , 20 . 4 , 19 . 3 , 18 . 4 , 18 . 1 , 18 . 0 , 15 . 3 , 13 . 2 , 11 . 8 , 11 . 0 , − 3 . 0 , − 3 . 4 , − 3 . 7 , − 3 . 9 , − 4 . 2 , − 4 . 28 , − 4 . 34 ; lrms ( esi ) 1213 . 9 [ m + na ] + , 987 . 7 , 659 . 3 , 437 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 72 h 114 o 8 si 3 na 1213 . 7719 [ m + na ] + , found 1213 . 7760 ; [ α ] 20 d + 2 . 3 ( c 0 . 75 , chcl 3 ). tbsotf ( 0 . 40 ml , 1 . 74 mmol ) was added to a stirred solution of alcohol 41β ( 1 . 39 g , 1 . 17 mmol ) and 2 , 6 - lutidine ( 0 . 27 ml , 2 . 33 mmol ) in ch 2 cl 2 ( 23 ml ) at 0 ° c . after stirring for 1 h at ambient temperature , the reaction mixture was quenched by the addition of water ( 50 ml ) and extracted by ch 2 cl 2 . after drying over mgso 4 , followed by the evaporation of the solution under reduced pressure , the residue was purified by short column chromatography ( hexane / etoac 9 : 1 ) to yield 42 ( 1 . 51 g , 99 %) as a colorless oil : ir ( chcl 3 ) 2955 , 2928 , 2855 , 1615 , 1517 , 1461 , 1250 , 1074 , 1039 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 59 ( m , 6h ), 7 . 52 ( m , 2h ), 7 . 41 ( m , 9h ), 7 . 01 ( m , 2h ), 5 . 74 ( m , 2h ), 5 . 57 ( s , 1h ), 5 . 50 ( m , 1h ), 5 . 43 ( m , 1h ), 4 . 67 ( m , 1h ), 4 . 25 ( dd , j = 11 . 3 , 4 . 6 hz , 1h ), 4 . 04 ( m , 1h ), 3 . 94 ( s , 3h ), 3 . 78 ( m , 1h ), 3 . 70 ( m , 3h ), 3 . 49 ( m , 1h ), 3 . 16 ( m , 1h ), 2 . 72 ( m 1h ), 2 . 54 ( m , 1h ), 2 . 18 ( m , 1h ), 2 . 01 ( m , 1h ), 1 . 82 ( m , 3h ), 1 . 54 ( m , 6h ), 1 . 14 ( d , j = 6 . 9 hz , 3h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 1 . 10 ( d , j = 6 . 5 hz , 3h ), 1 . 05 ( s , 9h ), 1 . 03 ( s , 9h ), 1 . 02 ( s , 12h ), 0 . 98 ( d , j = 6 . 3 hz , 3h ), 0 . 94 ( s , 9h ), 0 . 87 ( d , j = 6 . 7 hz , 3h ), 0 . 24 ( s , 3h ), 0 . 22 ( s , 3h ), 0 . 17 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 6 , 144 . 5 , 144 . 3 , 134 . 4 , 133 . 1 , 132 . 6 , 131 . 5 , 128 . 6 , 127 . 7 , 127 . 6 , 127 . 1 , 126 . 8 , 126 . 7 , 113 . 3 , 100 . 4 , 86 . 7 , 81 . 9 , 79 . 8 , 74 . 9 , 73 . 3 , 72 . 2 , 66 . 4 , 65 . 1 , 55 . 1 , 42 . 3 , 41 . 5 , 38 . 8 , 35 . 9 , 34 . 5 , 31 . 3 , 31 . 2 , 30 . 8 , 30 . 7 , 26 . 3 , 25 . 99 , 25 . 97 , 25 . 91 , 22 . 6 , 20 . 3 , 19 . 2 , 18 . 5 , 18 . 10 , 18 . 05 , 15 . 1 , 14 . 1 , 13 . 1 , 12 . 4 , 10 . 6 , − 3 . 0 , − 3 . 2 , − 3 . 6 , − 4 . 2 , − 4 . 25 , − 4 . 30 ; lrms ( esi ) 1327 . 8 [ m + na ] + , 1147 . 7 , 833 . 3 , 631 . 3 , 429 . 2 , 364 . 3 , 301 . 1 ; hrms ( esi ) calcd for c 78 h 128 o 8 si 4 na 1327 . 8584 [ m + na ] + , found 1327 . 8693 ; [ α ] 20 d + 7 . 6 ( c 0 . 17 , chcl 3 ). dibal - h ( 1 . 0 m in hexane , 11 . 7 ml , 11 . 7 mmol ) was added dropwise to a stirred solution of tbs protected acetal 42 ( 1 . 53 g , 1 . 17 mmol ) in anhydrous ch 2 cl 2 ( 2 . 3 ml ) under an atmosphere of n 2 at 0 ° c . after stirring for additional 30 min at 0 ° c . the reaction mixture was quenched by the careful addition of aqueous saturated aqueous potassium sodium tartrate ( 30 ml ). the resulting mixture was stirred for 3 h at room temperature . the organic layer was separated , and the aqueous layer was extracted by ch 2 cl 2 ( 20 ml ). the combined organic layers were washed with brine and dried over mgso 4 followed by the evaporation of the organic solution under reduced pressure . the residue was purified by column chromatography ( etoac / hexane 1 : 9 ) to obtain pure 43 ( 1 . 35 g , 88 %) as a colorless oil : ir ( chcl 3 ) 3464 , 2956 , 2929 , 2856 , 1613 , 1514 , 1471 , 1252 , 1087 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 46 ( m , 6h ), 7 . 28 ( m , 1h ), 6 . 88 ( m , 2h ), 5 . 61 ( m , 2h ), 5 . 39 ( m , 1h ), 5 . 28 ( m , 1h ), 4 . 57 ( m , 1h ), 4 . 53 ( s , 2h ), 3 . 92 ( m , 2h ), 3 . 83 ( m , 1h ), 3 . 80 ( s , 3h ), 3 . 60 ( m , 2h ), 3 . 56 ( m , 2h ), 3 . 46 ( dd , j = 6 . 2 , 4 . 5 hz , 1h ), 3 . 37 ( m , 1h ), 3 . 03 ( m , 1h ), 2 . 86 ( m 1h ), 2 . 59 ( m , 1h ), 2 . 41 ( m , 1h ), 1 . 93 ( m , 1h ), 1 . 88 ( m , 1h ), 1 . 66 ( m , 3h ), 1 . 35 ( m , 5h ), 1 . 11 ( d , j = 7 . 0 hz , 3h ), 1 . 01 ( d , j = 6 . 8 hz , 3h ), 0 . 97 ( d , j = 6 . 8 hz , 3h ), 0 . 92 ( m , 27h ), 0 . 85 ( m , 10h ), 0 . 81 ( s , 9h ), 0 . 11 ( s , 3h ), 0 . 09 ( s , 3h ), 0 . 07 ( s , 3h ), 0 . 06 ( s , 6h ), 0 . 05 ( s , 6h ), 0 . 04 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 144 . 4 , 144 . 3 , 134 . 3 , 133 . 0 , 132 . 4 , 130 . 5 , 129 . 1 , 128 . 6 , 127 . 6 , 126 . 7 , 113 . 8 , 86 . 7 , 85 . 4 , 79 . 8 , 75 . 1 , 73 . 8 , 72 . 2 , 66 . 4 , 65 . 0 , 55 . 0 , 42 . 3 , 41 . 6 , 41 . 5 , 40 . 5 , 37 . 1 , 35 . 8 , 34 . 8 , 32 . 0 , 31 . 9 , 30 . 7 , 26 . 2 , 25 . 94 , 25 . 86 , 20 . 3 , 19 . 2 , 18 . 4 , 18 . 1 , 18 . 0 , 15 . 6 , 15 . 2 , 13 . 2 , 10 . 0 , − 3 . 0 , − 3 . 4 , − 3 . 8 , − 3 . 9 , − 4 . 2 , − 4 . 28 , − 4 . 34 , − 4 . 4 ; lrms ( esi ) 1329 . 8 [ m + na ] + , 707 . 3 , 413 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 78 h 130 o 8 si 4 na 1329 . 8741 [ m + na ] + , found 1329 . 8779 ; [ α ] 20 d − 8 . 9 ( c 0 . 46 , chcl 3 ). the alcohol 43 ( 1 . 35 g , 1 . 03 μmol ) in ch 2 cl 2 ( 20 ml ) was treated with dess - martin periodinane ( 0 . 66 g , 1 . 56 μmol ). after 1 h , the mixture was quenched with saturated aqueous nahco 3 ( 20 ml ) and na 2 s 2 o 3 ( 20 ml ). the aqueous layer was extracted with et 2 o ( 2 × 20 ml ) and the combined extracts were dried over anhydrous mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 9 : 1 ) provided the crude aldehyde as a colorless oil , which was used without further purification . crcl 2 ( 1 . 06 g , 8 . 62 mmol ) was added to a stirred solution of the crude aldehyde and 1 - bromoallyl trimethylsilane ( 1 . 28 g , 5 . 20 mmol ) in anhydrous thf ( 26 ml ) under an atmosphere of n 2 at room temperature and the mixture was stirred for additional 14 h at ambient temperature . the reaction mixture was diluted with hexane followed by filtration through celite . after the evaporation of the solvent under reduced pressure , the residue was purified by short silica gel column chromatography using etoac / hexane ( 1 : 9 ) as eluent . the foregoing product in thf ( 40 ml ) was cooled to 0 ° c . and nah ( 95 % w / w , 0 . 52 g , 20 . 6 mmol ) was added in one portion . the ice bath was removed after 15 min and the mixture was stirred for 2 h at ambient temperature . the reaction mixture was cooled to 0 ° c ., quenched with h 2 o ( 5 ml ) and extracted with et 2 o ( 2 × 20 ml ). the combined organic layers were washed with brine , dried over mgso 4 , filtered and the solvent removed under reduced pressure . the residue was purified by column chromatography ( hexane / etoac 49 : 1 ) to obtain 44 ( 1 . 17 g , 85 % for 3 steps ) as a colorless oil : ir ( chcl 3 ) 2956 , 2928 , 2856 , 1614 , 1514 , 1471 , 1462 , 1249 , 1088 , 836 , 772 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 46 ( m , 6h ), 7 . 27 ( m , 1h ), 6 . 86 ( m , 2h ), 6 . 58 ( ddd , j = 17 . 0 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 00 ( t , j = 11 . 0 hz , 1h ), 5 . 60 ( m , 3h ), 5 . 31 ( m , 2h ), 5 . 17 ( d , j = 16 . 9 hz , 1h ), 5 . 09 ( d , j = 10 . 4 hz , 1h ), 4 . 51 ( m , 3h ), 3 . 90 ( m , 2h ), 3 . 80 ( s , 3h ), 3 . 61 ( m , 1h ), 3 . 56 ( d , j = 3 . 7 hz , 1h ), 3 . 33 ( m , 2h ), 3 . 00 ( m , 1h ), 2 . 56 ( m , 1h ), 2 . 40 ( m , 1h ), 2 . 21 ( m , 1h ), 1 . 63 ( m , 3h ), 1 . 38 ( m , 2h ), 1 . 27 ( m , 3h ), 1 . 21 ( m , 2h ), 1 . 10 ( d , j = 6 . 7 hz , 3h ), 0 . 96 ( m , 3h ), 0 . 93 ( s , 9h ), 0 . 91 ( s , 9h ), 0 . 89 ( s , 9h ), 0 . 86 ( m , 6h ), 0 . 82 ( m , 6h ), 0 . 80 ( s , 9h ), 0 . 79 ( m , 3h ), 0 . 08 ( m , 6h ), 0 . 05 ( m , 6h ), 0 . 04 ( m , 6h ), 0 . 01 ( m , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 146 . 2 , 144 . 5 , 144 . 4 , 134 . 6 , 134 . 5 , 133 . 1 , 132 . 7 , 132 . 3 , 131 . 4 , 129 . 0 , 128 . 9 , 128 . 7 , 127 . 7 , 126 . 8 , 117 . 1 , 113 . 7 , 86 . 8 , 84 . 4 , 79 . 9 , 75 . 0 , 72 . 9 , 72 . 3 , 66 . 5 , 65 . 1 , 55 . 2 , 42 . 4 , 41 . 9 , 41 . 6 , 40 . 6 , 36 . 0 , 35 . 6 , 35 . 3 , 34 . 5 , 32 . 5 , 31 . 7 , 30 . 5 , 26 . 3 , 26 . 0 , 25 . 9 , 20 . 2 , 19 . 2 , 18 . 8 , 18 . 5 , 18 . 2 , 18 . 1 , 15 . 1 , 13 . 3 , 9 . 3 , − 2 . 9 , − 3 . 0 , − 3 . 3 , − 3 . 6 , − 3 . 7 , − 4 . 2 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1351 . 8 [ m + na ] + , 1171 . 7 , 1043 . 7 , 889 . 6 , 707 . 3 , 536 . 1 , 453 . 3 , 413 . 2 , 359 . 2 ; hrms ( esi ) calcd for c 81 h 132 o 7 si 4 na 1351 . 8948 [ m + na ] + , found 1351 . 9012 ; [ α ] 20 d + 1 . 1 ( c 1 . 7 , chcl 3 ). znbr 2 ( 0 . 41 g ) in 1 . 2 ml of 5 : 1 ch 2 cl 2 / meoh was added dropwise for 30 min to a stirred solution of trityl compound 44 ( 0 . 24 g , 0 . 18 μmol ) in 1 . 4 ml of 6 : 1 ch 2 cl 2 / meoh at 0 ° c . after 4 h , the reaction mixture was quenched with saturated aqueous nahco 3 ( 20 ml ) and extracted with et 2 o ( 2 × 10 ml ). the organic phase were separated , dried with mgso 4 , filtered and concentrated . the residue was purified by flash chromatography ( etoac / hexane 1 : 9 ) to yield 45 ( 0 . 15 g , 77 %) as a colorless oil : ir ( chcl 3 ) 3432 , 2956 , 2856 , 1613 , 1514 , 1471 , 1462 , 1360 , 1250 , 1082 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 29 ( m , 2h ), 6 . 88 ( m , 2h ), 6 . 58 ( ddd , j = 16 . 9 , 10 . 6 , 10 . 6 hz , 1h ), 6 . 00 ( t , j = 11 . 0 hz , 1h ), 5 . 63 ( m , 3h ), 5 . 38 ( t , j = 11 . 0 hz , 1h ), 5 . 27 ( dd , j = 11 . 2 , 8 . 3 hz , 1h ), 5 . 17 ( d , j = 16 . 8 hz , 1h ), 5 . 10 ( d , j = 10 . 3 hz , 1h ), 4 . 53 ( m , 3h ), 4 . 08 ( d , j = 4 . 4 hz , 2h ), 3 . 90 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 62 ( m , 1h ), 3 . 33 ( m , 2h ), 2 . 99 ( ddd , j = 10 . 0 , 6 . 8 , 3 . 2 hz , 1h ), 2 . 57 ( m , 1h ), 2 . 39 ( m , 1h ), 1 . 63 ( m , 3h ), 1 . 42 ( m , 3h ), 1 . 28 ( m , 5h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 0 . 97 ( d , j = 6 . 8 hz , 3h ), 0 . 96 ( d , j = 6 . 9 hz , 3h ), 0 . 93 ( s , 9h ), 0 . 91 ( s , 18h ), 0 . 89 ( m , 3h ), 0 . 88 ( s , 9h ), 0 . 81 ( d , j = 6 . 7 hz , 3h ), 0 . 80 ( d , j = 6 . 2 hz , 3h ), 0 . 10 ( s , 3h ), 0 . 09 ( s , 3h ), 0 . 08 ( s , 6h ), 0 . 06 ( s , 3h ), 0 . 05 ( s , 6h ), 0 . 03 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 146 . 9 , 135 . 2 , 134 . 6 , 133 . 0 , 132 . 7 , 132 . 3 , 131 . 4 , 129 . 2 , 129 . 1 , 128 . 9 , 127 . 93 , 127 . 90 , 127 . 2 , 84 . 4 , 80 . 0 , 75 . 0 , 72 . 8 , 72 . 2 , 66 . 6 , 63 . 9 , 55 . 2 , 42 . 4 , 41 . 8 , 41 . 7 , 40 . 5 , 35 . 9 , 35 . 2 , 34 . 6 , 32 . 6 , 31 . 6 , 30 . 5 , 26 . 3 , 25 . 99 , 25 . 96 , 25 . 93 , 20 . 2 , 19 . 2 , 18 . 8 , 18 . 5 , 18 . 2 , 18 . 1 , 15 . 1 , 13 . 2 , 9 . 2 , − 3 . 0 , − 3 . 3 , − 3 . 6 , − 3 . 7 , − 4 . 2 , − 4 . 4 , − 4 . 5 ; lrms ( esi ) 1109 . 8 [ m + na ] + , 823 . 6 , 691 . 5 , 559 . 4 ; hrms ( esi ) calcd for c 62 h 118 o 7 si 4 na 1109 . 7852 [ m + na ] + , found 1109 . 7897 ; [ α ] 20 d + 1 . 6 ( c 0 . 94 , chcl 3 ). the alcohol 45 ( 127 mg , 0 . 117 μmol ) in ch 2 cl 2 ( 4 ml ) was treated with dess - martin periodinane ( 75 mg , 0 . 18 μmol ). after 1 h , the mixture was quenched with saturated aqueous nahco 3 ( 5 ml ) and na 2 s 2 o 3 ( 5 ml ). the aqueous layer was extracted with et 2 o ( 2 × 10 ml ) and the combined extracts were dried over anhydrous mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 9 : 1 ) provided the crude aldehyde as a colorless oil , which was used for the next reaction without further purification . khmds ( 0 . 28 ml , 0 . 14 μmol , 0 . 5m solution in toluene ) was added dropwise to a stirred solution of bis ( 2 , 2 , 2 - trifluoroethyl )-( methoxycarbonylmethyl ) phosphate ( 0 . 030 ml , 0 . 14 μmol ) and 18 - crown - 6 ( 0 . 15 g , 0 . 57 mmol ) in thf ( 2 . 3 ml ) at − 78 ° c . thereafter , the aldehyde in thf ( 0 . 5 ml ) was added and the solution was stirred for 4 h at − 78 ° c . the reaction mixture was quenched by addition of a saturated aqueous nh 4 cl ( 5 ml ) and diluted with et 2 o ( 20 ml ). the organic phase was washed with brine ( 30 ml ), dried with mgso 4 , filtered and concentrated . the residue was purified by flash chromatography ( etoac / hexane 1 : 19 ) yielding ( e , z )- doubly unsaturated ester 46 ( 0 . 12 g , 86 % for 2 steps ) as a colorless oil : ir ( chcl 3 ) 2955 , 2929 , 2856 , 1722 , 1514 , 1471 , 1462 , 1250 , 1174 , 1085 , 1041 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 39 ( dd , j = 15 . 4 , 11 . 3 hz , 1h ), 7 . 29 ( m , 2h ), 6 . 88 ( m , 2h ), 6 . 59 ( ddd , j = 16 . 9 , 10 . 8 , 10 . 6 hz , 1h ), 6 . 55 ( t , j = 11 . 3 hz , 1h ), 6 . 01 ( t , j = 11 . 0 hz , 1h ), 6 . 00 ( dd , j = 15 . 7 , 7 . 0 hz , 1h ), 5 . 60 ( d , j = 11 . 3 hz , 1h ), 5 . 59 ( t , j = 10 . 4 hz , 1h ), 5 . 39 ( t , j = 10 . 4 hz , 1h ), 5 . 27 ( dd , j = 11 . 0 , 8 . 3 hz , 1h ), 5 . 18 ( d , j = 16 . 8 hz , 1h ), 5 . 11 ( d , j = 10 . 3 hz , 1h ), 4 . 54 ( m , 3h ), 3 . 96 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 74 ( s , 3h ), 3 . 63 ( m , 1h ), 3 . 34 ( m , 2h ), 3 . 00 ( m , 1h ), 2 . 57 ( m , 2h ), 1 . 64 ( m , 3h ), 1 . 55 ( m , 1h ), 1 . 46 ( t , j = 5 . 9 hz , 2h ), 1 . 26 ( m , 5h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 1 . 05 ( d , j = 6 . 7 hz , 3h ), 0 . 97 ( d , j = 6 . 9 hz , 3h ), 0 . 96 ( d , j = 7 . 1 hz , 3h ), 0 . 94 ( s , 9h ), 0 . 92 ( s , 9h ), 0 . 91 ( s , 9h ), 0 . 87 ( s , 9h ), 0 . 83 ( d , j = 6 . 4 hz , 3h ), 0 . 82 ( d , j = 6 . 0 hz , 3h ), 0 . 13 ( s , 3h ), 0 . 11 ( s , 3h ), 0 . 10 ( s , 3h ), 0 . 09 ( s , 3h ), 0 . 06 ( s , 3h ), 0 . 05 ( s , 6h ), 0 . 04 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 159 . 0 , 147 . 3 , 145 . 5 , 134 . 6 , 132 . 9 , 132 . 8 , 132 . 4 , 131 . 4 , 129 . 0 , 128 . 9 , 126 . 9 , 117 . 1 , 115 . 5 , 113 . 7 , 84 . 4 , 80 . 0 , 75 . 0 , 72 . 9 , 72 . 1 , 66 . 5 , 55 . 2 , 50 . 9 , 43 . 5 , 42 . 5 , 41 . 8 , 40 . 5 , 36 . 0 , 35 . 3 , 34 . 5 , 32 . 5 , 31 . 6 , 30 . 5 , 26 . 3 , 25 . 99 , 25 . 96 , 25 . 91 , 20 . 2 , 19 . 2 , 18 . 8 , 18 . 5 , 18 . 2 , 18 . 1 , 15 . 0 , 13 . 4 , 9 . 2 , − 3 . 0 , − 3 . 2 , − 3 . 3 , − 3 . 6 , − 3 . 7 , − 4 . 1 , − 4 . 4 , − 4 . 5 ; lrms ( esi ) 1163 . 9 [ m + na ] + , 1009 . 8 , 684 . 3 , 610 . 2 , 513 . 4 ; hrms ( esi ) calcd for c 65 h 120 o 8 si 4 na 1163 . 7958 [ m + na ] + , found 1163 . 7985 ; [ α ] 20 d − 9 . 3 ( c 1 . 2 , chcl 3 ). the ester 46 ( 81 mg , 71 μmol ) was added to ch 2 cl 2 ( 2 ml ) and h 2 o ( 0 . 1 ml ) and ddq ( 20 mg , 88 μmol ) was added at 0 ° c . after 1 h of stirring at 0 ° c ., the reaction mixture was quenched by adding saturated aqueous nahco 3 ( 5 ml ). the organic phase was washed with saturated aqueous nahco 3 ( 3 × 10 ml ) and brine , dried over mgso 4 , filtered and concentrated . purification by flash column chromatography ( etoac / hexane 1 : 9 ) furnished 47 ( 64 mg , 88 %) as a colorless oil : ir ( chcl 3 ) 3541 , 2956 , 2929 , 2856 , 1722 , 1639 , 1471 , 1462 , 1377 , 1360 , 1254 , 1175 , 1086 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 34 ( dd , j = 15 . 4 , 11 . 2 hz , 1h ), 6 . 61 ( ddd , j = 16 . 8 , 10 . 7 , 10 . 6 hz , 1h ), 6 . 51 ( t , j = 11 . 3 hz , 1h ), 6 . 06 ( t , j = 11 . 0 hz , 1h ), 5 . 96 ( dd , j = 15 . 4 , 7 . 1 hz , 1h ), 5 . 56 ( d , j = 11 . 3 hz , 1h ), 5 . 39 ( t , j = 10 . 1 hz , 1h ), 5 . 38 ( t , j = 10 . 3 hz , 1h ), 5 . 22 ( dd , j = 11 . 0 , 8 . 5 hz , 1h ), 5 . 17 ( d , j = 18 . 7 hz , 1h ), 5 . 09 ( d , j = 10 . 1 hz , 1h ), 4 . 50 ( m , 1h ), 3 . 92 ( m , 1h ), 3 . 71 ( m , 1h ), 3 . 70 ( s , 3h ), 3 . 44 ( m , 1h ), 3 . 32 ( m , 1h ), 2 . 74 ( m , 1h ), 2 . 52 ( m , 2h ), 2 . 31 ( br , 1h ), 1 . 61 ( m , 4h ), 1 . 39 ( m , 2h ), 1 . 31 ( m , 2h ), 1 . 26 ( m , 3h ), 1 . 00 ( d , j = 6 . 7 hz , 3h ), 0 . 93 ( d , j = 6 . 9 hz , 3h ), 0 . 92 ( d , j = 6 . 7 hz , 3h ), 0 . 86 ( m , 27h ), 0 . 84 ( m , 6h ), 0 . 82 ( m , 12h ), 0 . 05 ( s , 9h ), 0 . 02 ( s , 3h ), 0 . 01 ( s , 6h ), 0 . 00 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 147 . 3 , 145 . 5 , 135 . 3 , 132 . 7 , 132 . 6 , 132 . 3 , 129 . 9 , 126 . 8 , 117 . 7 , 115 . 5 , 79 . 9 , 77 . 6 , 76 . 6 , 72 . 1 , 66 . 5 , 51 . 0 , 43 . 5 , 42 . 4 , 41 . 5 , 37 . 7 , 36 . 1 , 35 . 7 , 35 . 0 , 32 . 1 , 31 . 5 , 30 . 6 , 26 . 3 , 25 . 9 , 25 . 9 , 20 . 4 , 19 . 4 , 18 . 5 , 18 . 1 , 17 . 9 , 17 . 7 , 15 . 3 , 13 . 3 , 6 . 9 , − 3 . 0 , − 3 . 4 , − 3 . 7 , − 4 . 1 , − 4 . 2 , − 4 . 4 ; lrms ( esi ) 1043 . 6 [ m + na ] + , 889 . 6 , 757 . 5 , 625 . 4 , 393 . 3 ; hrms ( esi ) calcd for c 57 h 112 o 7 si 4 na 1043 . 7383 [ m + na ] + , found 1043 . 7417 ; [ α ] 20 d − 25 . 3 ( c 0 . 61 , chcl 3 ). a stirred solution of alcohol 47 ( 25 mg , 24 μmol ) in 3 . 4 ml of 12 : 5 etoh / thf was treated with 1n aqueous koh ( 0 . 24 ml ) and the mixture was refluxed gently for 3 h . the ethanolic solution was concentrated and then diluted with et 2 o ( 4 ml ). after the solution was acidified to ph3 with 1n aqueous hcl , the organic phase was separated and aqueous phase was extracted with et 2 o ( 2 × 5 ml ). the combined organic phase was dried with mgso 4 , filtered , concentrated and the residue was used without further purification : ir ( chcl 3 ) 2956 , 2929 , 2857 , 1693 , 1635 , 1600 , 1471 , 1462 , 1254 , 1088 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 33 ( dd , j = 15 . 2 , 11 . 3 hz , 1h ), 6 . 61 ( t , j = 11 . 4 hz , 1h ), 6 . 61 ( m , 1h ), 6 . 07 ( t , j = 11 . 0 hz , 1h ), 6 . 02 ( dd , j = 15 . 8 , 7 . 2 hz , 1h ), 5 . 58 ( d , j = 11 . 3 hz , 1h ), 5 . 39 ( m , 2h ), 5 . 23 ( dd , j = 11 . 0 , 8 . 2 hz , 1h ), 5 . 18 ( d , j = 16 . 8 hz , 1h ), 5 . 09 ( d , j = 10 . 2 hz , 1h ), 4 . 50 ( m , 1h ), 3 . 92 ( m , 1h ), 3 . 73 ( m , 1h ), 3 . 46 ( dd , j = 7 . 3 , 2 . 6 hz , 1h ), 3 . 34 ( m , 1h ), 2 . 78 ( m , 1h ), 2 . 54 ( m , 2h ), 1 . 66 ( m , 4h ), 1 . 42 ( m , 4h ), 1 . 24 ( m , 3h ), 1 . 01 ( d , j = 6 . 8 hz , 3h ), 0 . 95 ( d , j = 6 . 7 hz , 3h ), 0 . 94 ( d , j = 6 . 7 hz , 3h ), 0 . 88 ( m , 30h ), 0 . 84 ( m , 15h ), 0 . 09 ( s , 3h ), 0 . 07 ( s , 3h ), 0 . 06 ( s , 6h ), 0 . 02 ( s , 6h ), 0 . 01 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 171 . 2 , 148 . 2 , 147 . 3 , 135 . 2 , 133 . 2 , 132 . 7 , 132 . 3 , 123 . 0 , 127 . 0 , 117 . 7 , 115 . 2 , 79 . 9 , 77 . 6 , 76 . 5 , 72 . 1 , 66 . 4 , 43 . 5 , 42 . 6 , 41 . 6 , 37 . 8 , 36 . 0 , 35 . 8 , 34 . 9 , 32 . 1 , 31 . 5 , 30 . 6 , 26 . 2 , 25 . 93 , 25 . 87 , 20 . 3 , 19 . 4 , 18 . 4 , 18 . 10 , 18 . 05 , 17 . 7 , 15 . 3 , 13 . 6 , 6 . 9 − 3 . 0 , − 3 . 4 , − 3 . 7 , − 4 . 1 , − 4 . 19 , − 4 . 24 , − 4 . 4 ; lrms ( esi ) 1029 . 7 [ m + na ] + , 875 . 6 , 743 . 6 , 611 . 4 , 593 . 4 , 393 . 3 ; hrms ( esi ) calcd for c 56 h 110 o 7 si 4 na 1029 . 7226 [ m + na ] + , found 1029 . 7274 ; [ α ] 20 d − 25 . 7 ( c 0 . 54 , chcl 3 ). a solution of 48 in thf ( 2 ml ) was treated at 0 ° c . with et 3 n ( 0 . 020 ml , 147 μmol ) and 2 , 4 , 6 - trichlorobenzoyl chloride ( 0 . 019 ml , 122 μmol ). the reaction mixture was stirred at 0 ° c . for 30 min and then added to 4 - dmap ( 12 ml , 0 . 02 m solution in toluene ) at 25 ° c . after stirring for 12 h , the reaction mixture was concentrated , et 2 o ( 10 ml ) was added and the crude was washed with 1n hcl ( 2 × 5 ml ) and dried over mgso 4 . purification by flash column chromatography ( etoac / hexane 1 : 49 ) furnished the macrolactone ( 19 mg , 78 % for 2 steps ) as a colorless oil : ir ( chcl 3 ) 2955 , 2929 , 2857 , 1716 , 1642 , 1474 , 1225 , 1043 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 6 . 98 ( dd , j = 14 . 8 , 11 . 3 hz , 1h ), 6 . 55 ( m , 1h ), 6 . 52 ( t , j = 11 . 2 hz , 1h ), 6 . 04 ( t , j = 10 . 5 hz , 1h ), 6 . 01 ( dd , j = 15 . 4 , 6 . 4 hz , 1h ), 5 . 59 ( d , j = 11 . 2 hz , 1h ), 5 . 58 ( m , 1h ), 5 . 38 ( t , j = 10 . 6 hz , 1h ), 5 . 33 ( dd , j = 11 . 3 , 8 . 1 hz , 1h ), 5 . 19 ( d , j = 16 . 6 hz , 1h ), 5 . 11 ( d , j = 10 . 5 hz , 1h ), 5 . 06 ( dd , j = 7 . 6 , 3 . 7 hz , 1h ), 4 . 52 ( m , 1h ), 4 . 01 ( m , 1h ), 3 . 63 ( m , 1h ), 3 . 19 ( d , j = 6 . 2 hz , 1h ), 3 . 03 ( m , 1h ), 2 . 58 ( m , 1h ), 2 . 52 ( m , 2h ), 1 . 81 ( m , 4h ), 1 . 45 ( m , 3h ), 1 . 25 ( m , 3h ), 1 . 09 ( m , 3h ), 1 . 02 ( d , j = 6 . 8 hz , 3h ), 1 . 01 ( d , j = 7 . 0 hz , 3h ), 0 . 97 ( d , j = 6 . 6 hz , 3h ), 0 . 95 ( d , j = 6 . 4 hz , 3h ), 0 . 91 ( s , 9h ), 0 . 89 ( s , 9h ), 0 . 88 ( s , 9h ), 0 . 86 ( s , 9h ), 0 . 77 ( d , j = 6 . 4 hz , 3h ), 0 . 75 ( d , j = 6 . 5 hz , 3h ), 0 . 10 ( s , 3h ), 0 . 07 ( s , 3h ), 0 . 06 ( s , 3h ), 0 . 04 ( s , 3h ), 0 . 033 ( s , 6h ), 0 . 026 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 5 , 143 . 1 , 141 . 8 , 133 . 9 , 132 . 7 , 131 . 8 , 130 . 2 , 129 . 8 , 128 . 0 , 118 . 4 , 118 . 1 , 81 . 0 , 78 . 0 , 70 . 4 , 66 . 5 , 62 . 5 , 43 . 1 , 42 . 3 , 41 . 4 , 39 . 1 , 35 . 2 , 34 . 8 , 34 . 5 , 31 . 6 , 30 . 3 , 29 . 7 , 29 . 3 , 26 . 2 , 26 . 0 , 25 . 94 , 25 . 85 , 20 . 2 , 19 . 7 , 18 . 5 , 18 . 24 , 18 . 16 , 18 . 08 , 16 . 2 , 14 . 0 , 9 . 9 , − 2 . 7 , − 3 . 4 , − 3 . 5 , − 3 . 8 , − 3 . 9 , − 4 . 2 , − 4 . 3 ; [ α ] 20 d − 18 . 1 ( c 0 . 24 , chcl 3 ). a stirred solution of macrolactone 49 ( 18 mg , 18 μmol ) in thf ( 3 ml ) at 0 ° c . was treated with 3n hcl ( 10 ml , prepared by adding 2 . 5 ml of conc . hcl to 7 . 5 ml meoh ). after 24 h at room temperature , the reaction mixture was diluted with etoac ( 4 ml ) and h 2 o ( 4 ml ). the organic phase was saved and the aqueous phase was extracted with etoac ( 2 × 4 ml ). the combined organic phase was washed with saturated aqueous nahco 3 ( 10 ml ), dried with mgso 4 , filtered and concentrated . the residue was purified by flash chromatography ( etoac / hexane 3 : 2 ) to yield 1 as a white solid ( 5 . 3 mg , 55 %): ir ( chcl 3 ) 3406 , 2960 , 2924 , 2872 , 1693 , 1637 , 1461 , 1378 , 1274 , 1181 , 1069 , 998 , 738 cm − 1 ; 1 h nmr ( 600 mhz , cd 3 od ) δ 7 . 21 ( dd , j = 15 . 6 , 11 . 1 hz , 1h ), 6 . 71 ( ddd , j = 16 . 9 , 11 . 0 , 10 . 6 hz , 1h ), 6 . 65 ( dd , j = 11 . 3 , 11 . 3 hz , 1h ), 6 . 17 ( dd , j = 15 . 6 , 6 . 7 hz , 1h ), 6 . 06 ( dd , j = 11 . 1 , 11 . 1 hz , 1h ), 5 . 56 ( d , j = 11 . 3 hz , 1h ), 5 . 55 ( dd , j = 11 . 0 , 11 . 0 hz , 1h ), 5 . 41 ( dd , j = 11 . 1 , 8 . 8 hz , 1h ), 5 . 34 ( dd , j = 10 . 7 , 10 . 6 hz , 1h ), 5 . 25 ( dd , j = 16 . 8 , 1 . 8 hz , 1h ), 5 . 15 ( d , j = 10 . 1 hz , 1h ), 5 . 14 ( dd , j = 7 . 0 , 5 . 0 hz , 1h ), 4 . 65 ( ddd , j = 9 . 5 , 9 . 5 , 3 . 3 hz , 1h ), 4 . 05 ( ddd , j = 10 . 6 , 3 . 7 , 2 . 8 hz , 1h ), 3 . 17 ( ddq , j = 10 . 1 , 6 . 8 , 6 . 6 hz , 1h ), 3 . 10 ( dd , j = 8 . 1 , 2 . 9 hz , 1h ), 2 . 76 ( m , 1h ), 2 . 60 ( m , 1h ), 1 . 89 ( m , 1h ), 1 . 84 ( dddd , j = 12 . 9 , 11 . 2 , 6 . 4 , 5 . 4 hz , 1h ), 1 . 60 ( m , 1h ), 1 . 58 ( m , 1h ), 1 . 54 ( m , 1h ), 1 . 50 ( ddd , j = 14 . 1 , 10 . 7 , 3 . 5 hz , 1h ), 1 . 42 ( ddd , j = 14 . 0 , 10 . 0 , 2 . 7 hz , 1h ), 1 . 25 ( ddd , j = 13 . 7 , 10 . 6 , 3 . 6 hz , 1h ), 1 . 15 ( d , j = 6 . 9 hz , 3h ), 1 . 12 ( d , j = 7 . 0 hz , 3h ), 1 . 10 ( m , 1h ), 1 . 07 ( d , j = 6 . 9 hz , 3h ), 1 . 01 ( d , j = 6 . 8 hz , 3h ), 0 . 95 ( d , j = 6 . 5 hz , 3h ), 0 . 93 ( d , j = 6 . 5 hz , 3h ). 0 . 90 ( m , 1h ), 0 . 71 ( dddd , j = 12 . 9 , 12 . 8 , 8 . 7 , 4 . 9 hz , 1h ); 13 c nmr ( 150 mhz , cd 3 od ) δ 168 . 10 , 146 . 42 , 144 . 90 , 134 . 87 , 134 . 54 , 133 . 43 , 131 . 32 , 131 . 27 , 128 . 60 , 118 . 58 , 118 . 04 , 80 . 37 , 78 . 64 , 73 . 73 , 70 . 41 , 65 . 53 , 44 . 07 , 42 . 28 , 40 . 84 , 40 . 65 , 35 . 84 , 35 . 78 , 35 . 33 , 32 . 75 , 32 . 51 , 31 . 23 , 21 . 81 , 19 . 36 , 18 . 08 , 15 . 98 , 13 . 80 , 10 . 41 ; lrms ( esi ) 555 . 3 [ m + na ] + , 449 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 32 h 52 o 6 na 555 . 3662 [ m + na ] + , found 555 . 3665 ; [ α ] 20 d − 22 . 6 ( c 0 . 27 , meoh ). 3n hcl ( 10 ml , prepared by adding 2 . 5 ml of conc . hcl to 7 . 5 ml meoh ) was added to a stirred solution of the macrolactonization precursor 48 ( 23 mg , 23 μmol ) in thf ( 3 ml ) at 0 ° c . after 24 h at room temperature , the reaction mixture was diluted with etoac ( 4 ml ) and h 2 o ( 4 ml ). the organic phase was retained and aqueous phase was extracted with etoac ( 2 × 4 ml ). the combined organic phase was washed with saturated aqueous nahco 3 ( 10 ml ), dried with mgso 4 , filtered and concentrated . the residue was purified by flash chromatography ( etoac / hexane 3 : 2 ) to yield the product 50 ( 4 . 5 mg , 36 %) as a colorless oil : ir ( chcl 3 ) 3399 , 2917 , 2849 , 1713 , 1635 , 1600 , 1461 , 1439 , 1197 , 1178 , 970 , 757 cm − 1 ; 1 h nmr ( 600 mhz , cd 3 od ) δ 7 . 36 ( dd , j = 15 . 3 , 11 . 2 hz , 1h ), 6 . 67 ( ddd , j = 16 . 9 , 11 . 1 , 10 . 6 hz , 1h ), 6 . 63 ( dd , j = 11 . 3 , 11 . 3 hz , 1h ), 6 . 14 ( dd , j = 15 . 4 , 8 . 3 hz , 1h ), 6 . 03 ( dd , j = 11 . 0 , 1 . 0 hz , 1h ), 5 . 59 ( d , j = 11 . 4 hz , 1h ), 5 . 43 ( dd , j = 10 . 7 , 10 . 7 hz , 1h ), 5 . 42 ( dd , j = 10 . 8 , 9 . 2 hz , 1h ), 5 . 32 ( dd , j = 10 . 4 , 10 . 4 hz , 1h ), 5 . 17 ( dd , j = 16 . 8 , 2 . 0 hz , 1h ), 5 . 08 ( d , j = 10 . 2 hz , 1h ), 4 . 61 ( ddd , j = 12 . 9 , 8 . 5 , 4 . 6 hz , 1h ), 3 . 80 ( ddd , j = 8 . 9 , 4 . 4 , 4 . 4 hz , 1h ), 3 . 69 ( s , 3h ), 3 . 63 ( m , 1h ), 3 . 46 ( t , j = 5 . 8 hz , 1h ), 3 . 13 ( dd , j = 8 . 0 , 3 . 2 hz , 1h ), 2 . 93 ( m , 1h ), 2 . 71 ( m , 1h ), 2 . 38 ( m , 1h ), 1 . 73 ( m , 1h ), 1 . 56 - 1 . 53 ( m , 3h ), 1 . 52 - 1 . 46 ( m , 2h ), 1 . 44 - 1 . 36 ( m , 3h ), 1 . 09 ( d , j = 6 . 9 hz , 3h ), 0 . 98 ( d , j = 6 . 8 hz , 3h ), 0 . 96 ( d , j = 6 . 6 hz , 3h ), 0 . 95 ( m , 2h ), 0 . 94 ( d , j = 6 . 9 hz , 3h ), 0 . 87 ( d , j = 6 . 6 hz , 3h ), 0 . 86 ( d , j = 6 . 8 hz , 3h ); 13 c nmr ( 150 mhz , cd 3 od ) δ 168 . 4 , 148 . 5 , 146 . 9 , 135 . 7 , 135 . 4 , 133 . 85 , 133 . 82 , 130 . 6 , 128 . 2 , 117 . 7 , 116 . 2 , 79 . 2 , 78 . 5 , 74 . 8 , 72 . 4 , 65 . 8 , 51 . 5 , 45 . 1 , 43 . 2 , 43 . 0 , 41 . 0 , 37 . 2 , 36 . 5 , 34 . 0 , 33 . 3 , 33 . 1 , 31 . 0 , 20 . 7 , 18 . 6 , 18 . 4 , 16 . 7 , 13 . 8 , 7 . 8 ; lrms ( esi ) 587 . 5 [ m + na ] + , 559 . 2 , 485 . 2 , 413 . 3 , 355 . 1 , 212 . 1 ; hrms ( esi ) calcd for c 33 h 56 o 7 na 587 . 3924 [ m + na ] + , found 587 . 3953 ; [ α ] 20 d + 8 . 7 ( c 0 . 30 , cdcl 3 ). the procedure for 42 was used with 41α ( 0 . 58 g , 0 . 49 mmol ), tbsotf ( 0 . 17 ml , 0 . 74 mmol ) and 2 , 6 - lutidine ( 0 . 11 ml , 0 . 97 mmol ) to yield 0 . 62 g ( 97 %) of the product by flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 2955 , 2856 , 1615 , 1518 , 1462 , 1385 , 1251 , 1082 , 835 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 55 ( m , 6h ), 7 . 49 ( m , 2h ), 7 . 40 - 7 . 27 ( m , 9h ), 6 . 96 ( m , 2h ), 5 . 72 ( m , 2h ), 5 . 53 ( m , 1h ), 5 . 52 ( s , 1h ), 5 . 38 ( m , 1h ), 4 . 65 ( m , 1h ), 4 . 19 ( dd , j = 11 . 0 , 4 . 4 hz , 1h ), 4 . 03 ( m , 1h ), 3 . 95 ( d , j = 8 . 7 hz , 1h ), 3 . 86 ( m , 1h ), 3 . 84 ( s , 3h ), 3 . 66 ( d , j = 3 . 7 hz , 2h ), 3 . 56 ( t , j = 11 . 1 hz , 1h ), 3 . 50 ( m 1h ), 2 . 71 ( m , 1h ), 2 . 52 ( m , 1h ), 2 . 12 ( m , 1h ), 1 . 90 - 1 . 79 ( m , 2h ), 1 . 75 - 1 . 68 ( m , 3h ), 1 . 61 - 1 . 37 ( m , 6h ), 1 . 08 ( d , j = 6 . 6 hz , 6h ), 1 . 02 - 0 . 91 ( m , 36h ), 0 . 81 ( d , j = 6 . 5 hz , 3h ), 0 . 22 - 0 . 13 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 7 , 144 . 5 , 134 . 4 , 132 . 8 , 132 . 6 , 131 . 7 , 128 . 7 , 127 . 7 , 127 . 3 , 126 . 8 , 113 . 4 , 100 . 9 , 86 . 7 , 81 . 4 , 80 . 1 , 73 . 4 , 72 . 3 , 71 . 5 , 66 . 5 , 65 . 1 , 55 . 1 , 42 . 4 , 41 . 5 , 37 . 9 , 35 . 5 , 35 . 1 , 31 . 3 , 30 . 8 , 30 . 2 , 27 . 9 , 26 . 3 , 26 . 01 , 25 . 99 , 25 . 93 , 25 . 7 , 20 . 6 , 19 . 5 , 18 . 4 , 18 . 11 , 18 . 07 , 15 . 4 , 13 . 4 , 13 . 3 , 12 . 2 , 9 . 2 , − 2 . 9 , − 3 . 5 , − 3 . 7 , − 3 . 9 , − 4 . 1 , − 4 . 2 , − 4 . 3 , − 4 . 9 ; lrms ( esi ) 1328 . 0 [ m + na ] + , 782 . 5 , 659 . 3 , 437 . 2 ; hrms ( esi ) calcd for c 78 h 128 o 8 si 4 na 1327 . 8584 [ m + na ] + , found 1327 . 8624 ; [ α ] 20 d + 6 . 1 ( c 0 . 93 , chcl 3 ). the procedure for 43 was used with 51 ( 0 . 62 g , 0 . 47 mmol ) and dibal - h ( 1 . 0 m in hexane , 4 . 7 ml , 4 . 7 mmol ) to yield 0 . 54 g ( 87 %) of the product after flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 3479 , 2955 , 2928 , 2856 , 1613 , 1514 , 1471 , 1251 , 1084 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 56 - 7 . 52 ( m , 6h ), 7 . 38 - 7 . 33 ( m , 9h ), 7 . 30 ( m , 2h ), 6 . 94 ( m , 2h ), 5 . 72 ( m , 2h ), 5 . 52 ( m , 1h ), 5 . 38 ( m , 1h ), 4 . 67 ( d , j = 10 . 3 hz , 1h ), 4 . 65 ( m , 1h ), 4 . 60 ( d , j = 10 . 4 hz , 1h ), 4 . 03 ( m , 1h ), 3 . 83 ( s , 3h ), 3 . 70 ( m , 3h ), 3 . 65 ( d , j = 3 . 7 hz , 2h ), 3 . 49 ( m , 1h ), 3 . 02 ( m , 1h ), 2 . 71 ( m 1h ), 2 . 52 ( m , 1h ), 1 . 91 ( m , 2h ), 1 . 80 - 1 . 64 ( m , 3h ), 1 . 60 - 1 . 34 ( m , 8h ), 1 . 09 - 0 . 90 ( m , 54h ), 0 . 21 - 0 . 12 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 144 . 5 , 144 . 3 , 134 . 4 , 132 . 8 , 132 . 4 , 130 . 6 , 129 . 0 , 128 . 6 , 127 . 7 , 126 . 8 , 113 . 8 , 86 . 7 , 84 . 7 , 80 . 0 , 74 . 8 , 74 . 5 , 72 . 2 , 66 . 5 , 66 . 2 , 65 . 1 , 55 . 1 , 42 . 3 , 41 . 4 , 38 . 7 , 35 . 5 , 35 . 2 , 35 . 0 , 31 . 5 , 30 . 9 , 30 . 7 , 29 . 8 , 26 . 2 , 26 . 00 , 25 . 95 , 25 . 89 , 20 . 5 , 19 . 4 , 18 . 4 , 18 . 13 , 18 . 08 , 1 , 8 . 02 , 15 . 4 , 15 . 2 , 13 . 2 , 10 . 4 , − 3 . 0 , − 3 . 6 , − 3 . 7 , − 3 . 8 , − 4 . 18 , − 4 . 24 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1329 . 8 [ m + na ] + , 782 . 4 , 413 . 2 ; hrms ( esi ) calcd for c 78 h 130 o 8 si 4 na 1329 . 8741 [ m + na ] + , found 1329 . 8782 ; [ α ] 20 d − 6 . 8 ( c 0 . 66 , chcl 3 ). the procedure for 44 was used with 52 ( 0 . 54 g , 0 . 41 μmol ) and dess - martin periodinane ( 0 . 26 g , 0 . 61 μmol ), 1 - bromoallyl trimethylsilane ( 0 . 50 g , 2 . 60 mmol ) and crcl 2 ( 0 . 42 g , 3 . 42 mmol ), nah ( 95 % w / w , 0 . 21 g , 8 . 31 mmol ) to yield 0 . 46 g ( 83 % for 3 steps ) of the product by flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 2955 , 2928 , 2856 , 1613 , 1514 , 1462 , 1250 , 1069 , 835 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 58 - 7 . 54 ( m , 6h ), 7 . 40 - 7 . 35 ( m , 9h ), 7 . 33 - 7 . 30 ( m , 2h ), 6 . 96 - 6 . 93 ( m , 2h ), 6 . 69 ( ddd , j = 16 . 8 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 12 ( t , j = 11 . 0 hz , 1h ), 5 . 80 - 5 . 67 ( m , 3h ), 5 . 52 ( t , j = 10 . 4 hz , 1h ), 5 . 40 ( m , 1h ), 5 . 28 ( d , j = 16 . 8 hz , 1h ), 5 . 19 ( d , j = 10 . 2 hz , 1h ), 4 . 63 ( m , 3h ), 4 . 03 ( m , 1h ), 3 . 85 ( s , 3h ), 3 . 67 ( m , 2h ), 3 . 51 ( m , 1h ), 3 . 38 ( m , 1h ), 2 . 96 ( m , 1h ), 2 . 72 ( m , 1h ), 2 . 53 ( m , 1h ), 1 . 93 - 1 . 74 ( m , 2h ), 1 . 66 - 1 . 37 ( m , 7h ), 1 . 31 - 1 . 23 ( m , 3h ), 1 . 18 ( d , j = 6 . 8 hz , 3h ), 1 . 09 ( m , 6h ), 1 . 03 - 0 . 92 ( m , 45h ), 0 . 23 - 0 . 10 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 1 , 144 . 5 , 144 . 4 , 134 . 7 , 134 . 5 , 133 . 0 , 132 . 6 , 132 . 2 , 131 . 4 , 129 . 1 , 129 . 0 , 128 . 7 , 127 . 7 , 126 . 8 , 117 . 5 , 113 . 7 , 86 . 8 , 84 . 6 , 79 . 9 , 74 . 7 , 73 . 6 , 72 . 3 , 66 . 5 , 65 . 1 , 55 . 2 , 42 . 5 , 42 . 4 , 41 . 6 , 36 . 1 , 35 . 9 , 34 . 8 , 32 . 0 , 30 . 8 , 29 . 8 , 26 . 3 , 26 . 02 , 25 . 96 , 20 . 5 , 19 . 3 , 18 . 6 , 18 . 5 , 18 . 2 , 18 . 1 , 15 . 4 , 13 . 3 , 10 . 5 , − 2 . 9 , − 3 . 4 , − 3 . 7 , − 4 . 1 , − 4 . 2 , − 4 . 3 ; lrms ( esi ) 1352 . 0 [ m + na ] + , 782 . 5 , 647 . 6 , 619 . 6 , 437 . 2 ; hrms ( esi ) calcd for c 81 h 132 o 7 si 4 na 1351 . 8948 [ m + na ] + , found 1351 . 8987 ; [ α ] 20 d − 8 . 6 ( c 1 . 6 , chcl 3 ). the procedure for 45 was used with 53 ( 0 . 46 g , 0 . 35 μmol ) and znbr 2 ( 0 . 41 g in 5 . 8 ml of 24 : 5 ch 2 cl 2 / meoh ) to yield 0 . 21 g ( 55 %) of the product after flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 3410 , 2956 , 2929 , 2856 , 1614 , 1514 , 1471 , 1462 , 1251 , 1075 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 28 ( m , 2h ), 6 . 87 ( m , 2h ), 6 . 60 ( ddd , j = 16 . 8 , 10 . 7 , 10 . 6 hz , 1h ), 6 . 03 ( t , j = 11 . 0 hz , 1h ), 5 . 67 - 5 . 57 ( m , 3h ), 5 . 41 ( m , 1h ), 5 . 29 ( m , 1h ), 5 . 20 ( d , j = 18 . 2 hz , 1h ), 5 . 11 ( d , j = 10 . 2 hz , 1h ), 4 . 56 ( m , 3h ), 4 . 10 ( d , j = 4 . 4 hz , 1h ), 3 . 93 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 66 - 3 . 57 ( m , 2h ), 3 . 40 ( dd , j = 4 . 6 , 2 . 6 hz , 1h ), 3 . 28 ( dd , j = 6 . 2 , 4 . 2 hz , 1h ), 2 . 85 ( m , 1h ), 2 . 60 ( m , 1h ), 2 . 39 ( m , 1h ), 1 . 79 ( m , 1h ), 1 . 70 ( m , 1h ), 1 . 66 - 1 . 56 ( m , 2h ), 1 . 51 - 1 . 19 ( m , 8h ), 1 . 09 ( d , j = 6 . 8 hz , 3h ), 0 . 98 ( d , j = 6 . 8 hz , 3h ), 0 . 97 ( d , j = 6 . 9 hz , 3h ), 0 . 92 - 0 . 86 ( m , 45h ), 0 . 11 - 0 . 00 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 135 . 2 , 134 . 7 , 132 . 8 , 132 . 7 , 132 . 3 , 131 . 4 , 129 . 2 , 129 . 1 , 129 . 0 , 117 . 4 , 113 . 7 , 84 . 6 , 80 . 0 , 74 . 7 , 73 . 6 , 72 . 2 , 66 . 6 , 63 . 9 , 63 . 3 , 55 . 3 , 42 . 4 , 41 . 7 , 36 . 1 , 35 . 8 , 34 . 8 , 31 . 9 , 30 . 8 , 29 . 8 , 26 . 3 , 26 . 0 , 25 . 9 , 20 . 5 , 19 . 4 , 19 . 3 , 18 . 6 , 18 . 5 , 18 . 1 , 15 . 3 , 13 . 3 , 10 . 5 , − 3 . 0 , − 3 . 4 , − 3 . 7 , − 4 . 2 , − 4 . 3 , − 4 . 5 ; lrms ( esi ) 1109 . 9 [ m + na ] + , 947 . 8 , 782 . 5 , 689 . 2 , 615 . 2 , 541 . 1 , 413 . 3 , 306 . 3 ; hrms ( esi ) calcd for c 62 h 118 o 7 si 4 na 1109 . 7856 [ m + na ] + , found 1109 . 7902 ; [ α ] 20 d − 12 . 0 ( c 1 . 7 , chcl 3 ). the procedure for 46 was used with 54 ( 117 mg , 0 . 108 μmol ) and dess - martin periodinane ( 69 mg , 0 . 16 μmol ), bis ( 2 , 2 , 2 - trifluoroethyl )-( methoxycarbonylmethyl ) phosphate ( 0 . 027 ml , 0 . 13 μmol ), 18 - crown - 6 ( 0 . 14 g , 0 . 53 mmol ) and khmds ( 0 . 26 ml , 0 . 13 μmol , 0 . 5 m solution in toluene ) to yield 69 mg ( 56 % for 2 steps ) of the product after flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2856 , 1722 , 1640 , 1514 , 1471 , 1462 , 1250 , 1174 , 1080 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 44 ( dd , j = 15 . 2 , 11 . 3 hz , 1h ), 7 . 28 ( m , 2h ), 6 . 88 ( m , 2h ), 6 . 60 ( ddd , j = 16 . 7 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 56 ( t , j = 11 . 3 hz , 1h ), 6 . 04 ( dd , j = 15 . 5 , 7 . 1 hz , 1h ), 6 . 00 ( t , j = 11 . 0 hz , 1h ), 5 . 62 ( m , 2h ), 5 . 42 ( m , 1h ), 5 . 27 ( m , 1h ), 5 . 21 ( d , j = 16 . 8 hz , 1h ), 5 . 11 ( d , j = 10 . 3 hz , 1h ), 4 . 54 ( m , 3h ), 3 . 97 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 74 ( s , 3h ), 3 . 60 ( m , 1h ), 3 . 40 ( m , 1h ), 3 . 29 ( m , 1h ), 2 . 86 ( m , 1h ), 2 . 57 ( m , 2h ), 1 . 80 - 1 . 67 ( m , 3h ), 1 . 55 - 1 . 41 ( m , 4h ), 1 . 40 - 1 . 20 ( m , 4h ), 1 . 09 ( d , j = 6 . 8 hz , 3h ), 1 . 06 ( d , j = 6 . 8 hz , 3h ), 0 . 99 ( d , j = 6 . 6 hz , 3h ), 0 . 98 ( d , j = 6 . 7 hz , 3h ), 0 . 95 - 0 . 85 ( m , 42h ), 0 . 13 - 0 . 00 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 159 . 0 , 147 . 3 , 145 . 5 , 134 . 7 , 132 . 9 , 132 . 7 , 132 . 3 , 131 . 4 , 129 . 1 , 129 . 0 , 126 . 9 , 117 . 4 , 115 . 5 , 113 . 7 , 84 . 6 , 80 . 0 , 74 . 7 , 73 . 6 , 72 . 1 , 66 . 5 , 55 . 3 , 51 . 0 , 43 . 5 , 42 . 4 , 41 . 6 , 36 . 1 , 35 . 8 , 34 . 8 , 31 . 9 , 30 . 7 , 29 . 8 , 26 . 3 , 26 . 0 , 25 . 9 , 20 . 5 , 19 . 3 , 18 . 6 , 18 . 5 , 18 . 1 , 15 . 3 , 13 . 4 , 10 . 5 , − 3 . 0 , − 3 . 3 , − 3 . 7 , − 4 . 10 , − 4 . 15 , − 4 . 19 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1163 . 8 [ m + na ] + , 1057 . 7 , 782 . 4 , 541 . 1 ; hrms ( esi ) calcd for c 65 h 120 o 8 si 4 na 1163 . 7958 [ m + na ] + , found 1163 . 8000 ; [ α ] 20 d − 16 . 7 ( c 0 . 33 , chcl 3 ). the procedure for 47 was used with 55 ( 68 mg , 60 μmol ) and ddq ( 15 mg , 66 μmol ) to yield 56 mg ( 92 %) of the product after flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 3499 , 2956 , 2929 , 2856 , 1723 , 1641 , 1471 , 1462 , 1255 , 1175 , 1081 , 836 , 773 cm − ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 35 ( dd , j = 15 . 2 , 11 . 3 hz , 1h ), 6 . 64 ( ddd , j = 16 . 9 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 52 ( t , j = 11 . 3 hz , 1h ), 6 . 07 ( t , j = 11 . 0 hz , 1h ), 5 . 96 ( dd , j = 15 . 5 , 7 . 1 hz , 1h ), 5 . 56 ( d , j = 11 . 3 hz , 1h ), 5 . 44 - 5 . 33 ( m , 2h ), 5 . 26 - 5 . 21 ( m , 1h ), 5 . 17 ( d , j = 16 . 7 hz , 1h ), 5 . 07 ( d , j = 10 . 1 hz , 1h ), 4 . 49 ( m , 1h ), 3 . 92 ( m , 1h ), 3 . 73 - 3 . 67 ( m , 5h ), 3 . 34 ( m , 1h ), 3 . 25 ( br , 1h ), 2 . 73 ( m , 1h ), 2 . 52 ( m , 2h ), 1 . 82 - 1 . 50 ( m , 4h ), 1 . 44 - 1 . 16 ( m , 7h ), 1 . 01 ( d , j = 6 . 8 hz , 3h ), 0 . 97 ( d , j = 7 . 1 hz , 3h ), 0 . 93 ( d , j = 6 . 9 hz , 3h ), 0 . 90 ( d , j = 6 . 9 hz , 3h ), 0 . 88 - 0 . 81 ( m , 42h ), 0 . 08 - 0 . 00 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 147 . 3 , 145 . 5 , 136 . 5 , 132 . 8 , 132 . 7 , 132 . 6 , 129 . 6 , 126 . 8 , 117 . 3 , 115 . 5 , 79 . 8 , 78 . 4 , 74 . 2 , 72 . 1 , 66 . 5 , 51 . 0 , 43 . 5 , 42 . 5 , 41 . 4 , 36 . 0 , 35 . 9 , 35 . 8 , 35 . 0 , 32 . 4 , 31 . 9 , 30 . 7 , 26 . 3 , 26 . 0 , 25 . 9 , 20 . 4 , 19 . 4 , 18 . 5 , 18 . 12 , 18 . 08 , 17 . 98 , 17 . 4 , 15 . 3 , 13 . 4 , 10 . 8 , − 3 . 0 , − 3 . 4 , − 3 . 7 , − 4 . 1 , − 4 . 2 , − 4 . 3 , − 4 . 4 , − 4 . 8 ; lrms ( esi ) 1043 . 7 [ m + na ] + , 889 . 6 , 758 . 2 , 684 . 2 , 610 . 1 ; hrms ( esi ) calcd for c 57 h 112 o 7 si 4 na 1043 . 7383 [ m + na ] + , found 1043 . 7435 ; [ α ] 20 d − 9 . 4 ( c 0 . 62 , chcl 3 ). the procedure for 48 was used with 56 ( 56 mg , 55 μmol ) and 1n aqueous koh ( 0 . 54 ml ) to yield 57 , which was used without further purification : ir ( chcl 3 ) 2956 , 2929 , 2857 , 1693 , 1634 , 1471 , 1462 , 1254 , 1082 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 34 ( dd , j = 15 . 1 , 11 . 4 hz , 1h ), 6 . 64 ( ddd , j = 16 . 5 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 61 ( t , j = 11 . 2 hz , 1h ), 6 . 07 ( t , j = 11 . 0 hz , 1h ), 6 . 01 ( dd , j = 15 . 5 , 7 . 2 hz , 1h ), 5 . 58 ( d , j = 11 . 3 hz , 1h ), 5 . 44 - 5 . 34 ( m , 2h ), 5 . 23 ( dd , j = 11 . 0 , 8 . 2 hz , 1h ), 5 . 17 ( d , j = 18 . 0 hz , 1h ), 5 . 08 ( d , j = 10 . 1 hz , 1h ), 4 . 50 ( m , 1h ), 3 . 92 ( m , 1h ), 3 . 69 ( m , 1h ), 3 . 35 ( m , 1h ), 2 . 75 ( m , 1h ), 2 . 54 ( m , 2h ), 1 . 74 - 1 . 56 ( m , 4h ), 1 . 49 - 1 . 20 ( m , 7h ), 1 . 02 ( d , j = 6 . 8 hz , 3h ), 0 . 98 ( d , j = 7 . 2 hz , 3h ), 0 . 94 ( d , j = 7 . 0 hz , 3h ), 0 . 90 - 0 . 82 ( m , 45h ), 0 . 09 - 0 . 01 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 171 . 1 , 148 . 2 , 147 . 4 , 136 . 4 , 132 . 7 , 132 . 6 , 129 . 6 , 127 . 0 , 117 . 4 , 115 . 1 , 79 . 8 , 78 . 4 , 74 . 2 , 72 . 1 , 66 . 5 , 43 . 5 , 42 . 6 , 41 . 5 , 36 . 0 , 35 . 9 , 35 . 8 , 35 . 0 , 31 . 9 , 30 . 8 , 29 . 7 , 26 . 3 , 26 . 0 , 25 . 9 , 20 . 4 , 19 . 3 , 18 . 5 , 18 . 13 , 18 . 08 , 17 . 97 , 17 . 4 , 15 . 4 , 13 . 7 , 10 . 8 , − 3 . 0 , − 3 . 4 , − 3 . 7 , − 4 . 1 , − 4 . 2 , − 4 . 3 , − 4 . 4 , − 4 . 8 ; lrms ( esi ) 1029 . 8 [ m + na ] + , 832 . 3 , 758 . 3 , 684 . 3 , 610 . 2 , 541 . 2 ; hrms ( esi ) calcd for c 56 h 110 o 7 si 4 na 1029 . 7226 [ m + na ] + , found 1029 . 7255 ; [ α ] 20 d − 6 . 5 ( c 0 . 17 , chcl 3 ). the procedure for 49 was used with 57 , et 3 n ( 0 . 046 ml , 33 μmol ), 2 , 4 , 6 - trichlorobenzoyl chloride ( 0 . 043 ml , 28 μmol ) and 4 - dmap ( 27 ml , 0 . 02 m solution in toluene ) to yield 42 mg ( 78 % for 2 steps ) of 58 after flash column chromatography ( etoac / hexane 1 : 49 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2856 , 1704 , 1638 , 1471 , 1462 , 1378 , 1361 , 1255 , 1086 , 1044 , 1004 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 6 . 98 ( dd , j = 15 . 3 , 11 . 3 hz , 1h ), 6 . 58 ( ddd , j = 16 . 9 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 42 ( t , j = 11 . 4 hz , 1h ), 5 . 94 ( t , j = 9 . 2 hz , 1h ), 5 . 92 ( dd , j = 9 . 5 , 5 . 2 hz , 1h ), 5 . 55 ( m , 1h ), 5 . 42 ( d , j = 11 . 6 hz , 1h ), 5 . 33 - 5 . 21 ( m , 3h ), 5 . 12 ( d , j = 15 . 1 hz , 1h ), 4 . 99 ( d , j = 9 . 7 hz , 1h ), 4 . 54 ( m , 1h ), 3 . 99 ( m , 1h ), 3 . 44 ( m , 1h ), 3 . 17 ( m , 1h ), 2 . 99 ( m , 1h ), 2 . 54 ( m , 1h ), 2 . 19 ( m , 1h ), 1 . 99 ( m , 1h ), 1 . 61 - 1 . 42 ( m , 7h ), 1 . 37 - 1 . 18 ( m , 3h ), 1 . 10 ( d , j = 6 . 9 hz , 3h ), 1 . 05 ( d , j = 7 . 1 hz , 3h ), 1 . 00 ( d , j = 6 . 3 hz , 3h ), 0 . 98 ( d , j = 6 . 4 hz , 3h ), 0 . 98 - 0 . 82 ( m , 36h ), 0 . 79 ( d , j = 6 . 6 hz , 3h ), 0 . 66 ( d , j = 6 . 7 hz , 3h ), 0 . 11 - 0 . 01 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 4 , 146 . 5 , 143 . 9 , 134 . 3 , 132 . 7 , 132 . 2 , 130 . 8 , 129 . 8 , 127 . 9 , 117 . 4 , 117 . 1 , 81 . 6 , 78 . 0 , 77 . 1 , 73 . 0 , 66 . 7 , 46 . 9 , 45 . 7 , 41 . 2 , 37 . 5 , 35 . 8 , 35 . 1 , 34 . 5 , 31 . 1 , 29 . 7 , 26 . 2 , 26 . 1 , 26 . 0 , 25 . 9 , 20 . 5 , 19 . 5 , 19 . 1 , 18 . 5 , 18 . 4 , 18 . 2 , 17 . 9 , 17 . 3 , 16 . 9 , 7 . 9 , − 2 . 6 , − 3 . 4 , − 3 . 5 , − 4 . 3 , − 4 . 4 , − 4 . 6 ; lrms ( esi ) 1011 . 7 [ m + na ] + , 803 . 5 , 633 . 1 , 544 . 2 , 413 . 2 ; hrms ( esi ) calcd for c 56 h 108 o 6 si 4 na 1011 . 7121 [ m + na ] + , found 1011 . 7164 ; [ α ] 20 d − 61 . 6 ( c 2 . 8 , chcl 3 ). 3n hcl ( 10 ml , prepared by adding 2 . 5 ml of conc . hcl to 7 . 5 ml meoh ) was added to a stirred solution of macrolactone 58 ( 42 mg , 42 μmol ) in thf ( 3 ml ) at 0 ° c . after 24 h at room temperature , the reaction mixture was diluted with etoac ( 4 ml ) and h 2 o ( 4 ml ). the organic phase was retained and the aqueous phase was extracted with etoac ( 2 × 4 ml ). the combined organic phase was washed with saturated aqueous nahco 3 ( 10 ml ), dried with mgso 4 , filtered and concentrated . the residue was purified by flash chromatography ( etoac / hexane 3 : 2 ) to yield 59 ( 7 . 9 mg , 35 %) as a colorless oil : ir ( chcl 3 ) 3415 , 2961 , 2917 , 2849 , 1681 , 1637 , 1461 , 1279 , 1067 , 965 , 758 cm − 1 ; 1 h nmr ( 600 mhz , cd 3 od ) δ 7 . 05 ( dd , j = 15 . 3 , 11 . 3 hz , 1h ), 6 . 65 ( ddd , j = 16 . 9 , 10 . 2 , 10 . 1 hz , 1h ), 6 . 53 ( dd , j = 11 . 5 , 11 . 5 hz , 1h ), 5 . 97 ( dd , j = 15 . 3 , 9 . 5 hz , 1h ), 5 . 94 ( dd , j = 11 . 0 , 11 . 0 hz , 1h ), 5 . 60 ( dd , j = 10 . 8 , 9 . 6 hz , 1h ), 5 . 41 ( d , j = 11 . 5 hz , 1h ), 5 . 20 ( dd , j = 10 . 5 , 10 . 3 hz , 1h ), 5 . 11 ( dd , j = 16 . 9 , 2 . 0 hz , 1h ), 5 . 10 ( dd , j = 9 . 7 , 2 . 1 hz , 1h ), 5 . 01 ( d , j = 10 . 1 hz , 1h ), 4 . 60 ( ddd , j = 10 . 1 , 9 . 7 , 2 . 7 hz , 1h ), 3 . 94 ( ddd , j = 11 . 0 , 2 . 1 , 2 . 0 hz , 1h ), 3 . 38 ( ddd , j = 9 . 8 , 3 . 0 , 2 . 0 hz , 1h ), 3 . 09 ( ddq , j = 13 . 0 , 7 . 0 , 4 . 9 hz , 1h ), 3 . 01 ( dd , j = 8 . 3 , 2 . 7 hz , 1h ), 2 . 70 ( m , 1h ), 2 . 23 ( ddd , j = 9 . 3 , 7 . 0 , 2 . 4 hz , 1h ), 2 . 07 ( ddd , j = 7 . 0 , 2 . 6 , 2 . 5 hz , 1h ), 1 . 67 ( m , 2h ), 1 . 56 ( ddd , j = 14 . 0 , 10 . 9 , 2 . 9 hz , 1h ), 1 . 51 ( m , 1h ), 1 . 47 ( ddd , j = 14 . 1 , 10 . 5 , 1 . 9 hz , 1h ), 1 . 17 ( d , j = 6 . 9 hz , 3h ), 1 . 13 ( m , 1h ), 1 . 11 ( d , j = 7 . 1 hz , 3h ), 1 . 09 ( d , j = 7 . 0 hz , 3h ), 1 . 02 ( d , j = 6 . 7 hz , 3h ), 1 . 00 ( m , 1h ), 0 . 93 ( d , j = 6 . 4 hz , 3h ), 0 . 92 ( m , 1h ), 0 . 78 ( m , 1h ), 0 . 76 ( d , j = 6 . 7 hz , 3h ). 0 . 74 ( m , 1h ); 13 c nmr ( 150 mhz , cd 3 od ) δ 168 . 3 , 147 . 6 , 145 . 3 , 135 . 4 , 134 . 3 , 133 . 5 , 131 . 3 , 131 . 0 , 130 . 1 , 118 . 1 , 81 . 2 , 79 . 9 , 77 . 6 , 72 . 0 , 65 . 1 , 45 . 9 , 44 . 8 , 42 . 4 , 38 . 7 , 36 . 0 , 35 . 6 , 31 . 8 , 29 . 8 , 27 . 8 , 22 . 2 , 19 . 8 , 18 . 4 , 17 . 6 , 16 . 4 , 9 . 1 ; lrms ( esi ) 555 . 3 [ m + na ] + , 443 . 2 ; hrms ( est ) calcd for c 32 h 52 o 6 555 . 3662 [ m + na ] + , found 555 . 3655 ; [ α ] 20 d − 76 . 2 ( c 0 . 45 , meoh ). dibal - h ( 19 . 8 ml , 19 . 8 mmol , 1 . 0 m solution in hexane ) was added at − 78 ° c . dropwise to ester 60 ( 3 . 59 g . 7 . 94 μmol ) in ch 2 cl 2 ( 40 ml ). after stirring for 1 h , the reaction mixture was quenched by addition of etoac ( 5 ml ) and saturated aqueous sodium potassium tartrate ( 80 ml ), followed by vigorous stirring for 4 h . the aqueous phase was extracted with ch 2 cl 2 ( 3 × 20 ml ) and the combined organic layers were washed with brine ( 40 ml ). after drying over mgso 4 , filtration and evaporation under vacuum , flash column chromatography ( hexane / etoac 3 : 7 ) provided 60 ( 2 . 51 g , 77 %) as a colorless oil : ir ( chcl 3 ) 3387 , 2934 , 2856 , 1612 , 1513 , 1472 , 1462 , 1360 , 1302 , 1249 , 1172 , 1039 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 42 - 7 . 38 ( m , 2h ), 7 . 03 - 6 . 98 ( m , 2h ), 4 . 58 ( d , j = 11 . 6 hz , 1h ), 4 . 53 ( d , j = 11 . 6 hz , 1h ), 3 . 92 ( s , 3h ), 3 . 70 ( d , j = 6 . 6 hz , 2h ), 3 . 64 ( m , 2h ), 3 . 38 ( dd , j = 8 . 8 , 7 . 6 hz , 1h ), 2 . 31 ( br , 1h ), 2 . 16 - 2 . 03 ( m , 1h ), 1 . 78 - 1 . 66 ( m , 2h ), 1 . 65 - 1 . 50 ( m , 2h ), 1 . 38 - 1 . 28 ( m , 1h ), 1 . 09 ( d , j = 6 . 9 hz , 3h ), 1 . 03 ( s , 9h ), 1 . 01 ( d , j = 6 . 9 hz , 3h ), 0 . 18 ( s , 3h ), 0 . 17 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 130 . 7 , 129 . 0 , 113 . 6 , 77 . 4 , 72 . 6 , 72 . 5 , 62 . 8 , 55 . 1 , 37 . 8 , 36 . 1 , 30 . 8 , 30 . 4 , 26 . 0 , 18 . 3 , 15 . 2 , 14 . 5 , − 3 . 8 , − 4 . 2 ; lrms ( esi ) 433 . 3 [ m + na ] + ; hrms ( esi ) calcd for c 23 h 42 o 4 sina 433 . 2750 [ m + na ] + , found 433 . 2765 ; [ α ] 20 d − 10 . 2 ( c 1 . 0 , chcl 3 ). tbscl ( 0 . 92 g , 6 . 11 mmol ) was added to a solution of above alcohol 61 ( 2 . 51 g , 6 . 11 mmol ) and imidazole ( 0 . 46 g , 6 . 76 mmol ) in ch 2 cl 2 ( 20 ml ). the resulting slurry was stirred for 1 h at room temperature . the organic phase was washed with water ( 100 ml ) and brine ( 2 × 100 ml ). after drying over mgso 4 , filtration and evaporation under vacuum , the residue was used directly in next step : ir ( chcl 3 ) 2930 , 2856 , 1613 , 1513 , 1471 , 1360 , 1250 , 1098 , 1040 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 29 - 7 . 26 ( m , 2h ), 6 . 90 - 6 . 88 ( m , 2h ), 4 . 46 ( d , j = 11 . 6 hz , 1h ), 4 . 42 ( d , j = 11 . 6 hz , 1h ), 3 . 81 ( s , 3h ), 3 . 62 ( t , j = 6 . 3 hz , 2h ), 3 . 58 - 3 . 52 ( m , 2h ), 3 . 28 ( dd , j = 8 . 8 , 7 . 7 hz , 1h ), 2 . 02 - 1 . 94 ( m , 1h ), 1 . 66 - 1 . 54 ( m , 2h ), 1 . 52 - 1 . 39 ( m , 2h ), 1 . 28 - 1 . 18 ( m , 1h ), 0 . 99 ( d , j = 6 . 9 hz , 3h ), 0 . 94 ( s , 9h ), 0 . 92 ( s , 9h ), 0 . 89 ( d , j = 6 . 8 hz , 3h ), 0 . 09 ( s , 6h ), 0 . 07 ( s , 3h ), 0 . 06 ( 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 130 . 9 , 129 . 0 , 113 . 6 , 77 . 5 , 72 . 8 , 72 . 6 , 63 . 4 , 55 . 1 , 38 . 0 , 36 . 3 , 31 . 1 , 30 . 8 , 26 . 1 , 25 . 9 , 18 . 4 , 18 . 3 , 15 . 2 , 14 . 4 , − 3 . 8 , − 4 . 1 , − 5 . 3 ; lrms ( esi ) 547 . 4 [ m + na ] + 413 . 3 , 212 . 1 ; hrms ( esi ) calcd for c 29 h 56 o 4 si 2 na 547 . 3615 [ m + na ] + , found 547 . 3638 ; [ α ] 20 d − 9 . 9 ( c 2 . 5 , chcl 3 ). the pmb alcohol 62 ( 6 . 11 mmol ) was added to ch 2 cl 2 ( 19 ml ) then h 2 o ( 1 ml ) and ddq ( 1 . 80 g , 7 . 93 μmol ) were added . after 1 h of stirring , the reaction was quenched by adding saturated aqueous nahco 3 ( 100 ml ). the organic phase was washed with saturated aqueous nahco 3 ( 3 × 100 ml ) and brine , dried over mgso 4 filtered and concentrated . purification by flash column chromatography ( etoac / hexane 1 : 9 ) furnished 63 ( 2 . 23 g , 90 %) as a colorless oil : ir ( chcl 3 ) 3403 , 2928 , 2856 , 1472 , 1463 , 1388 , 1256 , 1100 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ3 . 59 - 3 . 50 ( m , 4h ), 3 . 46 ( dd , j = 5 . 5 , 3 . 7 hz , 1h ), 1 . 83 - 1 . 75 ( m , 1h ), 1 . 62 - 1 . 52 ( m , 2h ), 1 . 49 - 1 . 35 ( m , 2h ), 1 . 18 - 1 . 05 ( m , 1h ), 0 . 91 ( d , j = 7 . 0 hz , 3h ), 0 . 87 - 0 . 84 ( m , 21h ), 0 . 05 ( s , 3h ), 0 . 03 ( s , 3h ), 0 . 00 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 80 . 4 , 65 . 8 , 63 . 3 , 38 . 1 , 37 . 8 , 31 . 1 , 29 . 6 , 26 . 0 , 25 . 9 , 18 . 2 , 15 . 9 , 14 . 9 , 4 . 0 , − 4 . 2 , − 5 . 4 ; lrms ( esi ) 427 . 3 [ m + na ]+, 256 . 8 , 212 . 1 ; hrms ( esi ) calcd for c 21 h 48 o 3 si 2 na 427 . 3040 [ m + na ]+, found 427 . 3050 ; [ α ] 20 d − 14 . 0 ( c 0 . 6 , chcl 3 ). sulfur trioxide pyridine complex ( 2 . 63 g , 16 . 5 mmol ) was added to a stirred solution of alcohol 63 ( 2 . 23 g , 5 . 51 mmol ) and triethylamine ( 2 . 25 ml , 16 . 5 mmol ) in anhydrous ch 2 cl 2 ( 12 ml ) and dmso ( 22 ml ) at 0 ° c . the reaction mixture was stirred at ambient temperature for 1 h . the mixture was diluted with et 2 o ( 100 ml ) and washed with 0 . 5n aqueous hcl ( 50 ml ) and brine ( 10 ml ). the separated organic layer was dried over mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 4 : 1 ) provided the crude aldehyde as a colorless oil , which was used without further purification . a mixture of carbon tetrabromide ( 3 . 65 g , 11 . 0 mmol ) and triphenylphosphine ( 5 . 78 g , 22 . 0 mmol ) in ch 2 cl 2 ( 50 ml ) was stirred at 0 ° c . for 10 min . a solution of the crude aldehyde and 2 , 6 - lutidine ( 1 . 27 ml , 11 . 0 mmol ) in ch 2 cl 2 ( 5 ml ) was transferred via cannula to the reaction mixture . the reaction was stirred for an additional 2 h at 0 ° c ., then quenched with a saturated aqueous nh 4 cl ( 20 ml ). the layers were separated and the aqueous layer was extracted with ch 2 cl 2 ( 2 × 20 ml ). the combined layers were dried over mgso 4 , filtered and concentrated in vacuo . flash column chromatography over silica gel ( etoac / hexane 1 : 19 ) afforded the vinyl dibromide as a colorless oil . the vinyl dibromide in thf ( 18 ml ) was cooled to − 78 ° c . and treated with n - buli ( 8 . 6 ml , 13 . 8 mmol , 1 . 6 m solution in hexane ). the reaction was stirred for 1 h at − 78 ° c ., warmed to 20 ° c . and stirred an additional 1 h . saturated aqueous nh 4 cl ( 5 ml ) was added , the layers were separated and the aqueous layer was extracted with et 2 o . the combined organic layer was dried over mgso 4 , filtered and concentrated in vacuo . purification by flash column chromatography ( etoac / hexane 1 : 9 ) furnished 64 ( 1 . 20 g , 55 % for 3 steps ) as a colorless oil : ir ( chcl 3 ) 3313 , 2930 , 2857 , 1472 , 1463 , 1387 , 1361 , 1254 , 1099 , 835 , 774 , 627 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ3 . 74 ( m , 2h ), 3 . 66 ( dd , j = 4 . 7 , 3 . 8 hz , 1h ), 2 . 74 ( m , 1h ), 2 . 14 ( d , j = 2 . 5 hz , 1h ), 1 . 85 ( m , 1h ), 1 . 74 - 1 . 56 ( m , 4h ), 1 . 31 ( d , j = 7 . 1 hz , 3h ), 1 . 05 - 1 . 01 ( m , 18h ), 0 . 23 ( s , 3h ), 0 . 20 ( s , 3h ), 0 . 18 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 87 . 4 , 77 . 9 , 69 . 9 , 63 . 4 , 36 . 5 , 31 . 5 , 31 . 0 , 30 . 7 , 26 . 1 , 26 . 0 , 18 . 4 , 18 . 3 , 17 . 5 , 15 . 0 , − 3 . 9 , − 5 . 3 ; lrms ( esi ) 421 . 3 [ m + na ] + , 372 . 8 , 359 . 3 , 256 . 8 , 212 . 1 ; hrms ( esi ) calcd for c 22 h 46 o 2 si 2 na 421 . 2934 [ m + na ] + , found 421 . 2942 ; [ α ] 20 d − 5 . 3 ( c 1 . 3 , chcl 3 ). the procedure for 32 was used with 15 ( 1 . 31 g , 2 . 28 μmol ), 64 ( 1 . 20 g , 3 . 01 mmol ) and n - buli ( 1 . 88 ml , 1 . 20 mmol ) to yield the ynone ( 1 . 79 g , 86 %) after flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2929 , 2856 , 2209 , 1675 , 1471 , 1462 , 1385 , 1254 , 1093 , 836 , 775 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 56 - 7 . 53 ( m , 6h ), 7 . 38 - 7 . 25 ( m , 9h ), 5 . 79 ( dd , j = 15 . 6 , 7 . 2 hz , 1h ), 5 . 67 ( dt , j = 15 . 6 , 4 . 9 hz , 1h ), 4 . 36 ( m , 1h ), 3 . 69 - 3 . 66 ( m , 4h ), 3 . 63 ( t , j = 4 . 1 hz , 1h ), 2 . 86 ( m , 1h ), 2 . 72 ( m , 1h ), 2 . 45 ( m , 1h ), 1 . 76 ( m , 1h ), 1 . 67 - 1 . 51 ( m , 3h ), 1 . 34 ( m , 1h ), 1 . 29 ( d , j = 7 . 1 hz , 3h ), 1 . 14 ( d , j = 6 . 8 hz , 3h ), 1 . 00 - 0 . 97 ( m , 28h ), 0 . 18 - 0 . 13 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 186 . 0 , 144 . 2 , 132 . 8 , 128 . 6 , 127 . 9 , 127 . 7 , 126 . 8 , 96 . 7 , 86 . 8 , 83 . 1 , 77 . 8 , 71 . 6 , 64 . 8 , 63 . 2 , 50 . 1 , 42 . 3 , 37 . 2 , 31 . 7 , 30 . 9 , 30 . 2 , 26 . 0 , 25 . 9 , 25 . 8 , 18 . 3 , 18 . 2 , 18 . 0 , 17 . 3 , 15 . 4 , 14 . 8 , − 3 . 9 , − 4 . 1 , − 4 . 6 , − 4 . 7 , − 5 . 3 ; lrms ( esi ) 933 . 6 [ m + na ] + , 795 . 5 , 665 . 2 , 496 . 1 , 413 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 55 h 86 o 5 si 3 na 933 . 5681 [ m + na ] + , found 933 . 5692 ; [ α ] 20 d − 9 . 5 ( c 0 . 55 , chcl 3 ). the procedure for 33 was used with the above ynone ( 1 . 77 g , 1 . 94 μmol ), ( s , s )- noyori catalyst ( 0 . 26 g , 20 mol %) and i - proh ( 19 ml ) to yield 65 ( 1 . 69 g , 95 %) after flash column chromatography ( etoac / hexane 1 : 19 ) as a pale yellow oil : ir ( chcl 3 ) 3464 , 2929 , 2856 , 1471 , 1448 , 1386 , 1254 , 1090 , 836 , 774 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 56 - 7 . 54 ( m , 6h ), 7 . 39 - 7 . 26 ( m , 9h ), 5 . 78 ( dd , j = 15 . 7 , 6 . 4 hz , 1h ), 5 . 68 ( dt , j = 15 . 6 , 4 . 9 hz , 1h ), 4 . 57 ( m , 1h ), 4 . 06 ( m , 1h ), 3 . 71 - 3 . 67 ( m , 4h ), 3 . 62 ( t , j = 4 . 0 hz , 1h ), 2 . 74 ( m , 1h ), 2 . 50 ( m , 1h ), 2 . 46 ( d , j = 5 . 4 hz , 1h ), 1 . 82 ( m , 3h ), 1 . 72 - 1 . 54 ( m , 3h ), 1 . 36 ( m , 1h ), 1 . 24 ( d , j = 7 . 1 hz , 3h ), 1 . 13 ( d , j = 6 . 8 hz , 3h ), 1 . 04 - 0 . 94 ( m , 27h ), 0 . 21 - 0 . 14 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 3 , 133 . 8 , 128 . 6 , 127 . 7 , 127 . 2 , 126 . 8 , 87 . 8 , 86 . 8 , 83 . 1 , 77 . 7 , 72 . 5 , 65 . 0 , 63 . 5 , 59 . 4 , 41 . 9 , 40 . 6 , 36 . 4 , 31 . 7 , 30 . 7 , 26 . 01 , 25 . 96 , 25 . 9 , 18 . 3 , 18 . 0 , 17 . 4 , 15 . 2 , 14 . 5 , − 4 . 0 , − 4 . 1 , − 4 . 4 , − 4 . 5 , − 5 . 3 ; lrms ( esi ) 935 . 4 [ m + na ] + ; hrms ( esi ) calcd for c 55 h 88 o 5 si 3 na 935 . 5837 [ m + na ] + , found 935 . 5851 ; [ α ] 20 d − 10 . 5 ( c 0 . 86 , chcl 3 ). the procedure for 34 was used with alkyne 65 ( 1 . 69 g , 1 . 85 μmol ) and lindlar catalyst ( ca . 200 mg ) to yield 66 ( 1 . 70 g , quantitative ) as a pale yellow oil : ir ( chcl 3 ) 3477 , 2955 , 2856 , 1471 , 1448 , 1386 , 1254 , 1057 , 835 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 63 - 7 . 60 ( m , 6h ), 7 . 43 - 7 . 27 ( m , 9h ), 5 . 88 - 5 . 77 ( m , 2h ), 5 . 70 ( t , j = 10 . 1 hz , 1h ), 5 . 49 ( dd , j = 10 . 6 , 8 . 4 hz , 1h ), 4 . 78 ( m , 1h ), 4 . 06 ( m , 1h ), 3 . 76 - 3 . 72 ( m , 4h ), 3 . 58 ( t , j = 3 . 6 hz , 1h ), 2 . 89 ( m , 1h ), 2 . 63 ( m , 1h ), 2 . 20 ( d , j = 2 . 8 hz , 1h ), 1 . 73 - 1 . 48 ( m , 7h ), 1 . 18 ( d , j = 6 . 9 hz , 3h ), 1 . 15 ( d , j = 7 . 0 hz , 3h ), 1 . 08 - 1 . 02 ( m , 27h ), 0 . 29 - 0 . 20 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 3 , 134 . 9 , 134 . 4 , 131 . 5 , 128 . 6 , 127 . 7 , 127 . 0 , 126 . 8 , 86 . 7 , 79 . 8 , 72 . 8 , 65 . 0 , 64 . 7 , 63 . 5 , 42 . 1 , 39 . 7 , 37 . 9 , 35 . 9 , 31 . 4 , 29 . 9 , 26 . 2 , 26 . 0 , 25 . 9 , 20 . 1 , 18 . 4 , 18 . 3 , 18 . 0 , 14 . 9 , 14 . 5 , − 3 . 6 , − 3 . 8 , − 4 . 5 , − 4 . 6 , − 5 . 3 ; lrms ( esi ) 937 . 5 [ m + na ] + ; hrms ( esi ) calcd for c 55 h 90 o 5 si 3 na 937 . 5994 [ m + na ] + , found 937 . 6016 ; [ α ] 20 d + 2 . 1 ( c 0 . 92 , chcl 3 ). the procedure for 35 was used with alcohol 66 ( 1 . 70 g , 1 . 85 μmol ), tbsotf ( 0 . 94 ml , 4 . 07 mmol ) and 2 , 6 - lutidine ( 0 . 51 ml , 4 . 44 mmol ) to yield 67 ( 1 . 82 g , 96 %) by flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2856 , 1471 , 1448 , 1254 , 1092 , 1004 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 77 - 7 . 75 ( m , 6h ), 7 . 57 - 7 . 47 ( m , 9h ), 6 . 02 - 5 . 87 ( m , 2h ), 5 . 76 ( t , j = 10 . 8 hz , 1h ), 5 . 61 ( dd , j = 10 . 8 , 8 . 5 hz , 1h ), 4 . 88 ( m , 1h ), 4 . 24 ( m , 1h ), 3 . 88 ( m , 4h ), 3 . 75 ( m , 1h ), 2 . 94 ( m , 1h ), 2 . 73 ( m , 1h ), 1 . 83 ( m , 2h ), 1 . 75 ( m , 2h ), 1 . 57 ( m , 1h ), 1 . 46 - 1 . 41 ( m , 2h ), 1 . 31 ( d , j = 6 . 8 hz , 3h ), 1 . 30 ( d , j = 6 . 3 hz , 3h ), 1 . 24 - 1 . 13 ( m , 39h ), 0 . 44 - 0 . 34 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 4 , 134 . 4 , 132 . 9 , 132 . 2 , 128 . 7 , 127 . 7 , 126 . 8 , 86 . 8 , 80 . 2 , 72 . 3 , 66 . 6 , 65 . 1 , 63 . 6 , 42 . 4 , 41 . 6 , 38 . 4 , 35 . 7 , 31 . 6 , 29 . 9 , 26 . 3 , 26 . 0 , 19 . 6 , 18 . 5 , 18 . 4 , 18 . 2 , 15 . 1 , 13 . 2 , − 2 . 9 , − 3 . 6 , − 3 . 7 , − 4 . 2 , − 5 . 2 ; lrms ( esi ) 1051 . 6 [ m + na ] + , 918 . 6 , 769 . 5 , 637 . 4 , 413 . 2 ; hrms ( esi ) calcd for c 61 h 104 o 5 si 4 na 1051 . 6859 [ m + na ] + , found 1051 . 6848 [ α ] 20 d − 8 . 3 ( c 2 . 4 , chcl 3 ). the procedure for 36 was used with 67 ( 1 . 82 g , 1 . 77 μmol ) and hf - pyridine in pyridine ( 100 ml ) to yield 68 ( 1 . 15 g , 71 %) by flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 3349 , 2956 , 2929 , 2856 , 1471 , 1448 , 1254 , 1060 , 836 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 58 - 7 . 55 ( m , 6h ), 7 . 39 - 7 . 27 ( m , 9h ), 5 . 81 - 5 . 65 ( m , 2h ), 5 . 56 ( t , j = 10 . 7 hz , 1h ), 5 . 41 ( dd , j = 11 . 0 , 8 . 4 hz , 1h ), 4 . 67 ( m , 1h ), 4 . 05 ( m , 1h ), 3 . 69 - 3 . 63 ( m , 4h ), 3 . 53 ( m , 1h ), 2 . 73 ( m , 1h ), 2 . 52 ( m , 1h ), 1 . 64 ( m , 3h ), 1 . 58 - 1 . 48 ( m , 2h ), 1 . 30 - 1 . 20 ( m , 2h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 1 . 10 ( d , j = 6 . 6 hz , 3h ), 1 . 03 - 0 . 92 ( m , 30h ), 0 . 23 - 0 . 14 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 3 , 134 . 3 , 132 . 9 , 132 . 0 , 128 . 6 , 127 . 7 , 126 . 8 , 86 . 7 , 80 . 1 , 72 . 3 , 66 . 4 , 65 . 0 , 63 . 1 , 42 . 4 , 41 . 7 , 38 . 2 , 35 . 5 , 31 . 2 , 29 . 5 , 26 . 2 , 25 . 95 , 25 . 89 , 19 . 6 , 18 . 4 , 18 . 1 , 18 . 0 , 15 . 1 , 13 . 3 , − 2 . 9 , − 3 . 7 , − 3 . 8 , − 4 . 17 , − 4 . 24 , − 4 . 3 ; lrms ( esi ) 937 . 6 [ m + na ] + ; hrms ( esi ) calcd for c 55 h 90 o 5 si 3 na 937 . 5994 [ m + na ] + , found 937 . 6035 ; [ α ] 20 d − 10 . 8 ( c 0 . 84 , chcl 3 ). the procedure for 39 was used with alcohol 68 ( 1 . 15 g , 1 . 26 μmol ), dess - martin reagent ( 0 . 80 g , 1 . 89 mmol ) and ba ( oh ) 2 ( 0 . 17 g , 1 . 01 mmol ) and 38 ( 0 . 49 g , 1 . 27 mmol ) to yield 69 ( 1 . 22 g , 83 %) after flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2856 , 1693 , 1618 , 1518 , 1461 , 1388 , 1251 , 1080 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 70 - 7 . 68 ( m , 6h ), 7 . 60 - 7 . 57 ( m , 2h ), 7 . 52 - 7 . 39 ( m , 9h ), 7 . 11 ( m , 1h ), 7 . 07 - 7 . 04 ( m , 2h ), 6 . 54 ( d , j = 15 . 6 , hz , 1h ), 5 . 94 - 5 . 78 ( m , 2h ), 5 . 67 ( t , j = 10 . 9 hz , 1h ), 5 . 64 ( s , 1h ), 5 . 54 ( dd , j = 11 . 0 , 8 . 2 hz , 1h ), 4 . 80 ( m , 1h ), 4 . 28 ( dd , j = 11 . 3 , 4 . 6 hz , 1h ), 4 . 18 ( m , 1h ), 4 . 11 ( dd , j = 9 . 8 , 3 . 9 hz , 1h ), 3 . 94 ( s , 3h ), 3 . 81 ( m , 2h ), 3 . 71 ( m , 1h ), 3 . 66 ( m , 1h ), 3 . 12 ( m , 1h ), 2 . 87 ( m , 1h ), 2 . 66 ( m , 1h ), 2 . 47 ( m , 1h ), 2 . 34 ( m , 1h ), 2 . 19 ( m , 1h ), 1 . 90 - 1 . 73 ( m , 3h ), 1 . 67 - 1 . 51 ( m , 2h ), 1 . 45 ( d , j = 7 . 0 hz , 3h ), 1 . 23 ( d , j = 6 . 6 hz , 3h ), 1 . 22 ( d , j = 6 . 8 hz , 3h ), 1 . 16 - 1 . 05 ( m , 30h ), 0 . 96 ( d , j = 6 . 7 hz , 3h ), 0 . 36 - 0 . 26 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 200 . 4 , 159 . 6 , 147 . 2 , 144 . 2 , 134 . 1 , 133 . 0 , 131 . 9 , 130 . 9 , 128 . 5 , 127 . 8 , 127 . 6 , 127 . 1 , 126 . 7 , 113 . 3 , 100 . 6 , 86 . 6 , 82 . 7 , 79 . 8 , 72 . 7 , 72 . 1 , 66 . 3 , 64 . 9 , 55 . 0 , 46 . 8 , 42 . 3 , 41 . 5 , 37 . 9 , 35 . 3 , 32 . 0 , 31 . 7 , 30 . 8 , 26 . 1 , 25 . 9 , 19 . 5 , 18 . 3 , 18 . 0 , 17 . 9 , 14 . 7 , 13 . 1 , 12 . 3 , 10 . 4 , − 3 . 0 , − 3 . 7 , − 3 . 9 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1195 . 7 [ m + na ] + , 1051 . 8 ; hrms ( esi ) calcd for c 71 h 108 o 8 si 3 na 1195 . 7250 [ m + na ] + found 1195 . 7297 ; [ α ] 20 d + 9 . 1 ( c 1 . 2 , chcl 3 ). the procedure for 40 was used with 69 ( 1 . 22 g , 1 . 04 μmol ), nicl 2 . 6h 2 o ( 0 . 12 g , 0 . 52 mmol ) and nabh 4 ( 0 . 079 g , 2 . 08 mmol ) to yield 70 ( 0 . 80 g , 65 %) after flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2855 , 1713 , 1615 , 1518 , 1461 , 1388 , 1251 , 1077 , 1037 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 70 - 7 . 66 ( m , 6h ), 7 . 57 - 7 . 40 ( m , 1h ), 7 . 07 - 7 . 04 ( m , 2h ), 5 . 92 - 5 . 77 ( m , 2h ), 5 . 65 ( m , 1h ), 5 . 64 ( s , 1h ), 5 . 52 ( m , 1h ), 4 . 78 ( m , 1h ), 4 . 30 ( dd , j = 11 . 2 , 4 . 6 hz , 1h ), 4 . 14 ( m , 2h ), 3 . 94 ( s , 3h ), 3 . 79 ( d , j = 3 . 9 hz , 2h ), 3 . 73 ( t , j = 11 . 1 hz , 1h ), 3 . 61 ( m , 1h ), 2 . 92 - 2 . 79 ( m , 2h ), 2 . 72 ( t , j = 7 . 4 hz , 2h ), 2 . 65 ( m , 1h ), 2 . 22 ( m , 1h ), 1 . 91 - 1 . 71 ( m , 4h ), 1 . 65 - 1 . 56 ( m , 3h ), 1 . 51 ( m , 1h ), 1 . 43 ( d , j = 7 . 1 hz , 3h ), 1 . 35 ( m , 1h ), 1 . 20 ( d , j = 6 . 7 hz , 3h ), 1 . 14 - 1 . 12 ( m , 21h ), 1 . 08 ( d , j = 6 . 2 hz , 3h ), 1 . 05 - 1 . 03 ( m , 9h ), 0 . 96 ( d , j = 6 . 7 hz , 3h ), 0 . 34 - 0 . 25 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) 6 211 . 5 , 159 . 8 , 144 . 4 , 144 . 3 , 134 . 3 , 132 . 9 , 132 . 2 , 130 . 9 , 128 . 6 , 127 . 6 , 127 . 1 , 126 . 8 , 113 . 4 , 100 . 8 , 86 . 7 , 83 . 0 , 80 . 1 , 72 . 8 , 72 . 2 , 66 . 4 , 65 . 0 , 55 . 0 , 48 . 2 , 42 . 3 , 41 . 6 , 40 . 6 , 38 . 0 , 35 . 7 , 33 . 5 , 31 . 2 , 27 . 6 , 26 . 2 , 25 . 91 , 25 . 87 , 23 . 9 , 19 . 4 , 18 . 4 , 18 . 05 , 17 . 99 , 14 . 8 , 13 . 2 , 12 . 0 , 9 . 5 , − 3 . 0 , − 3 . 6 , − 3 . 8 , − 4 . 2 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1197 . 7 [ m + na ] + , 684 . 2 , 541 . 1 ; hrms ( esi ) calcd for c 71 h 110 o 8 si 3 na 1197 . 7406 [ m + na ] + , found 1197 . 7411 ; [ α ] 20 d + 4 . 6 ( c 1 . 1 , chcl 3 ). lial ( o - t - bu ) 3 h ( 2 . 0 ml , 1 . 0 m solution in thf ) was added to a solution of 70 ( 0 . 80 g , 0 . 68 mmol ) in thf ( 7 ml ). after 30 min of stirring at room temperature , the reaction was quenched with saturated aqueous nh 4 cl ( 1 ml ), stirring for 1 h , dried over mgso 4 , filtered , concentrated in vacuo , and chromatographed ( etoac / hexane 3 : 17 ) to provide the β isomer of 71 ( 0 . 76 g , 95 %) as a colorless oil : ir ( chcl 3 ) 3538 , 2929 , 2855 , 1615 , 1518 , 1461 , 1385 , 1251 , 1072 , 835 , 773 , 734 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 70 - 7 . 66 ( m , 6h ), 7 . 59 - 7 . 56 ( m , 2h ), 7 . 52 - 7 . 39 ( m , 9h ), 7 . 08 - 7 . 05 ( m , 2h ), 5 . 93 - 5 . 77 ( m , 2h ), 5 . 71 ( s , 1h ), 5 . 67 ( t , j = 10 . 2 hz , 1h ), 5 . 55 - 5 . 48 ( m , 1h ), 4 . 78 ( m , 1h ), 4 . 30 ( dd , j = 11 . 4 , 4 . 8 hz , 1h ), 4 . 15 ( m , 1h ), 4 . 09 ( m , 1h ), 3 . 94 ( s , 3h ), 3 . 88 ( dd , j = 10 . 0 , 1 . 5 hz , 1h ), 3 . 79 ( d , j = 3 . 9 hz , 2h ), 3 . 70 ( t , j = 11 . 1 hz , 1h ), 3 . 64 ( m , 1h ), 3 . 38 ( br , 1h ), 2 . 84 ( m , 1h ), 2 . 65 ( m , 1h ), 2 . 33 ( m , 1h ), 2 . 22 - 1 . 91 ( m , 2h ), 1 . 86 - 1 . 71 ( m , 3h ), 1 . 66 - 1 . 54 ( m , 4h ), 1 . 49 - 1 . 34 ( m , 3h ), 1 . 24 ( d , j = 7 . 0 hz , 3h ), 1 . 21 ( d , j = 6 . 6 hz , 3h ), 1 . 15 - 1 . 08 ( m , 21h ), 1 . 09 ( d , j = 6 . 9 hz , 3h ), 1 . 04 ( m , 9h ), 0 . 94 ( d , j = 6 . 7 hz , 3h ), 0 . 34 - 0 . 25 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 160 . 0 , 144 . 4 , 144 . 3 , 134 . 3 , 132 . 8 , 132 . 2 , 130 . 6 , 128 . 6 , 127 . 6 , 127 . 1 , 126 . 7 , 113 . 6 , 101 . 1 , 88 . 9 , 86 . 7 , 80 . 1 , 76 . 2 , 73 . 0 , 72 . 2 , 66 . 4 , 65 . 0 , 55 . 1 , 42 . 3 , 41 . 6 , 38 . 2 , 37 . 4 , 35 . 7 , 35 . 0 , 33 . 6 , 30 . 3 , 28 . 0 , 26 . 5 , 26 . 1 , 25 . 91 , 25 . 87 , 19 . 5 , 18 . 4 , 18 . 05 , 17 . 99 , 15 . 0 , 13 . 2 , 11 . 8 , 5 . 6 , − 3 . 0 , − 3 . 7 , − 3 . 8 , − 4 . 2 , − 4 . 3 ; lrms ( esi ) 1199 . 7 [ m + na ] + , 937 . 6 , 782 . 4 , 413 . 2 ; hrms ( esi ) calcd for c 71 h 112 o 8 si 3 na 1199 . 7563 [ m + na ] + , found 1199 . 7538 ; [ α ] 20 d + 8 . 9 ( c 0 . 46 , chcl 3 ). the procedure for 42 was used with 71 ( 0 . 76 g , 0 . 65 μmol ), tbsotf ( 0 . 22 ml , 0 . 98 mmol ) and 2 , 6 - lutidine ( 0 . 15 ml , 1 . 30 mmol ) to yield 72 ( 0 . 76 g , 92 %) after flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 2955 , 2929 , 2856 , 1615 , 1518 , 1471 , 1388 , 1251 , 1074 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 60 - 7 . 57 ( m , 6h ), 7 . 52 - 7 . 49 ( m , 2h ), 7 . 41 - 7 . 27 ( m , 9h ), 6 . 99 - 6 . 96 ( m , 2h ), 5 . 83 - 5 . 67 ( m , 2h ), 5 . 56 ( t , j = 9 . 2 hz , 1h ), 5 . 55 ( s , 1h ), 5 . 43 ( dd , j = 10 . 9 , 8 . 4 hz , 1h ), 4 . 69 ( m , 1h ), 4 . 21 ( m , 1h ), 4 . 06 ( m , 1h ), 3 . 84 ( s , 3h ), 3 . 81 ( m , 1h ), 3 . 76 - 3 . 70 ( m , 3h ), 3 . 60 ( t , j = 11 . 1 hz , 1h ), 3 . 54 ( m , 1h ), 2 . 74 ( m 1h ), 2 . 54 ( m , 1h ), 2 . 14 ( m , 1h ), 2 . 00 ( t , j = 6 . 7 hz , 1h ), 1 . 68 ( m , 3h ), 1 . 58 - 1 . 40 ( m , 5h ), 1 . 34 - 1 . 20 ( m , 3h ), 1 . 13 ( d , j = 6 . 8 hz , 3h ), 1 . 10 ( m , 3h ), 1 . 05 - 0 . 95 ( m , 42h ), 0 . 84 ( d , j = 6 . 4 hz , 3h ), 0 . 25 - 0 . 17 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 7 , 144 . 5 , 144 . 3 , 134 . 3 , 132 . 9 , 132 . 4 , 131 . 6 , 128 . 7 , 127 . 7 , 127 . 1 , 126 . 8 , 113 . 4 , 100 . 5 , 86 . 7 , 81 . 9 , 80 . 2 , 74 . 7 , 73 . 3 , 72 . 3 , 66 . 5 , 65 . 0 , 55 . 1 , 42 . 3 , 41 . 6 , 38 . 9 , 38 . 2 , 35 . 9 , 34 . 0 , 33 . 7 , 30 . 7 , 28 . 4 , 26 . 2 , 26 . 0 , 25 . 96 , 25 . 9 , 25 . 7 , 19 . 4 , 18 . 4 , 18 . 1 , 14 . 8 , 13 . 2 , 12 . 3 , 10 . 6 , − 3 . 0 , − 3 . 5 , − 3 . 8 , − 4 . 2 , − 4 . 3 ; lrms ( esi ) 1313 . 8 [ m + na ] + , 782 . 4 , 413 . 2 ; hrms ( esi ) calcd for c 77 h 126 o 8 si 4 na 1313 . 8428 [ m + na ] + , found 1313 . 8402 ; [ α ] 20 d + 9 . 5 ( c 0 . 38 , chcl 3 ). the procedure for 43 was used with 72 ( 0 . 76 g , 0 . 59 μmol ) and dibal - h ( 5 . 9 ml , 5 . 9 mmol ) to yield 73 ( 0 . 69 g , 90 %) after flash column chromatography ( etoac / hexane 3 : 17 ) as a colorless oil : ir ( chcl 3 ) 3484 , 2928 , 2856 , 1613 , 1514 , 1471 , 1360 , 1251 , 1037 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 62 - 7 . 58 ( m , 6h ), 7 . 47 - 7 . 34 ( m , 1h ), 7 . 02 - 7 . 00 ( m , 2h ), 5 . 82 - 5 . 68 ( m , 2h ), 5 . 55 ( t , j = 10 . 0 hz , 1h ), 5 . 46 - 5 . 41 ( m , 1h ), 4 . 70 ( m , 1h ), 4 . 66 ( s , 2h ), 4 . 04 ( m , 1h ), 3 . 97 ( m , 1h ), 3 . 94 ( s , 3h ), 3 . 77 ( m , 1h ), 3 . 70 ( d , j = 3 . 3 hz , 2h ), 3 . 59 ( dd , j = 6 . 6 , 4 . 3 hz , 1h ), 3 . 53 ( m , 1h ), 3 . 00 ( dd , j = 5 . 8 , 4 . 4 hz , 1h ), 2 . 72 ( m 1h ), 2 . 55 ( m , 1h ), 2 . 10 ( m , 1h ), 2 . 02 ( m , 1h ), 1 . 77 - 1 . 61 ( m , 5h ), 1 . 55 - 1 . 47 ( m , 3h ), 1 . 41 - 1 . 33 ( m , 5h ), 1 . 25 ( d , j = 7 . 0 hz , 3h ), 1 . 14 ( d , j = 6 . 9 hz , 3h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 1 . 05 - 0 . 94 ( m , 42h ), 0 . 25 - 0 . 16 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 144 . 3 , 144 . 2 , 134 . 3 , 132 . 9 , 132 . 2 , 130 . 5 , 129 . 2 , 128 . 6 , 127 . 6 , 126 . 8 , 113 . 8 , 86 . 7 , 85 . 6 , 80 . 1 , 75 . 1 , 73 . 4 , 72 . 2 , 66 . 4 , 65 . 0 , 55 . 0 , 42 . 3 , 41 . 5 , 40 . 5 , 38 . 2 , 37 . 0 , 35 . 7 , 34 . 7 , 33 . 7 , 28 . 3 , 26 . 2 , 25 . 9 , 19 . 4 , 18 . 4 , 18 . 1 , 15 . 7 , 14 . 8 , 13 . 1 , 10 . 1 , − 3 . 0 , − 3 . 6 , − 3 . 8 , − 3 . 9 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1315 . 8 [ m + na ] + , 937 . 6 ; hrms ( esi ) calcd for c 77 h 128 o 8 si 4 na 1315 . 8584 [ m + na ] + , found 1315 . 8534 ; [ α ] 20 d − 4 . 2 ( c 1 . 5 , chcl 3 ). the procedure for 44 was used with 73 ( 0 . 69 g , 0 . 53 μmol ), dess - martin reagent ( 0 . 34 g , 0 . 80 mmol ) and 1 - bromoallyltrimethylsilane ( 0 . 66 g , 2 . 65 mmol ), crcl 2 ( 0 . 54 g , 4 . 39 mmol ) and nah ( 0 . 27 g , 10 . 7 mmol ) to yield 74 ( 0 . 58 g , 82 % for 3 steps ) after flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2955 , 2929 , 2856 , 1613 , 1514 , 1471 , 1250 , 1063 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 63 - 7 . 60 ( m , 6h ), 7 . 43 - 7 . 31 ( m , 1h ), 6 . 99 - 6 . 97 ( m , 2h ), 6 . 74 ( ddd , j = 16 . 8 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 16 ( t , j = 11 . 0 hz , 1h ), 5 . 86 - 5 . 71 ( m , 3h ), 5 . 58 ( t , j = 9 . 8 hz , 1h ), 5 . 46 ( dd , j = 11 . 0 , 8 . 3 hz , 1h ), 5 . 31 ( d , j = 16 . 8 hz , 1h ), 5 . 23 ( d , j = 10 . 2 hz , 1h ), 4 . 75 - 4 . 63 ( m , 3h ), 4 . 09 ( m , 1h ), 3 . 86 ( s , 3h ), 3 . 81 ( m , 1h ), 3 . 73 ( d , j = 4 . 0 hz , 1h ), 3 . 55 ( m , 1h ), 3 . 49 ( m , 1h ), 3 . 18 ( m , 1h ), 2 . 77 ( m , 1h ), 2 . 57 ( m , 1h ), 1 . 91 - 1 . 78 ( m , 2h ), 1 . 73 - 1 . 50 ( m , 6h ), 1 . 49 - 1 . 35 ( m , 3h ), 1 . 26 ( d , j = 6 . 6 hz , 3h ), 1 . 15 ( d , j = 6 . 3 hz , 3h ), 1 . 13 ( d , j = 5 . 9 hz , 3h ), 1 . 10 - 0 . 97 ( m , 42h ), 0 . 28 - 0 . 19 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 144 . 5 , 144 . 4 , 134 . 6 , 134 . 4 , 133 . 0 , 132 . 5 , 132 . 4 , 131 . 3 , 129 . 1 , 129 . 0 , 128 . 7 , 127 . 7 , 126 . 8 , 117 . 2 , 113 . 7 , 86 . 8 , 84 . 3 , 80 . 3 , 75 . 0 , 72 . 6 , 72 . 3 , 66 . 5 , 65 . 1 , 55 . 1 , 42 . 4 , 41 . 6 , 40 . 7 , 38 . 0 , 36 . 0 , 35 . 3 , 35 . 2 , 34 . 0 , 28 . 2 , 26 . 3 , 26 . 03 , 26 . 00 , 25 . 97 , 25 . 7 , 19 . 4 , 18 . 8 , 18 . 5 , 18 . 2 , 18 . 14 , 18 . 09 , 14 . 8 , 13 . 3 , 9 . 4 , − 2 . 9 , − 3 . 5 , − 3 . 6 , − 3 . 8 , − 4 . 1 , − 4 . 2 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1337 . 8 [ m + na ] + , 537 . 4 , 243 . 1 ; hrms ( esi ) calcd for c 80 h 130 o 7 si 4 na 1337 . 8791 [ m + na ] + , found 1337 . 8785 ; [ α ] 20 d + 5 . 1 ( c 0 . 37 , chcl 3 ). the procedure for 45 was used with 74 ( 0 . 58 g , 0 . 22 μmol ), znbr ( 0 . 25 g , 1 . 11 mmol ) to yield 75 ( 0 . 42 g , 89 %) after flash column chromatography ( etoac / hexane 3 : 17 ) as a colorless oil : ir ( chcl 3 ) 3402 , 2956 , 2929 , 2856 , 1614 , 1514 , 1471 , 1251 , 1085 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 47 - 7 . 44 ( m , 2h ), 7 . 04 - 7 . 01 ( m , 2h ), 6 . 76 ( ddd , j = 16 . 8 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 19 ( t , j = 11 . 0 hz , 1h ), 5 . 87 - 5 . 72 ( m , 3h ), 5 . 59 ( t , j = 10 . 0 hz , 1h ), 5 . 45 ( dd , j = 10 . 9 , 8 . 3 hz , 1h ), 5 . 35 ( d , j = 16 . 8 hz , 1h ), 5 . 27 ( d , j = 10 . 2 hz , 1h ), 4 . 75 - 4 . 65 ( m , 3h ), 4 . 22 ( d , j = 4 . 5 hz , 2h ), 4 . 09 ( m , 1h ), 3 . 94 ( s , 3h ), 3 . 83 ( m , 1h ), 3 . 56 ( m , 1h ), 3 . 51 ( m , 1h ), 3 . 17 ( m , 1h ), 2 . 77 ( m , 1h ), 2 . 57 ( m , 1h ), 1 . 95 ( m , 1h ), 1 . 85 ( m , 1h ), 1 . 78 - 1 . 55 ( m , 8h ), 1 . 53 - 1 . 40 ( m , 3h ), 1 . 29 ( d , j = 6 . 7 hz , 3h ), 1 . 56 - 1 . 06 ( m , 45h ), 1 . 01 ( d , j = 6 . 7 hz , 3h ), 0 . 29 - 0 . 22 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 158 . 9 , 134 . 8 , 134 . 5 , 132 . 8 , 132 . 4 , 132 . 3 , 131 . 2 , 129 . 2 , 129 . 1 , 128 . 9 , 117 . 1 , 113 . 6 , 84 . 3 , 80 . 2 , 75 . 0 , 72 . 4 , 72 . 2 , 66 . 5 , 63 . 6 , 55 . 1 , 42 . 3 , 41 . 5 , 40 . 5 , 37 . 9 , 35 . 7 , 35 . 2 , 33 . 8 , 28 . 1 , 26 . 2 , 25 . 9 , 25 . 6 , 19 . 3 , 18 . 8 , 18 . 4 , 18 . 2 , 18 . 0 , 14 . 6 , 13 . 0 , 9 . 2 , − 3 . 0 , − 3 . 5 , − 3 . 7 , − 3 . 9 , − 4 . 3 , − 4 . 4 , − 4 . 5 ; lrms ( esi ) 1095 . 7 [ m + na ] + , 809 . 6 , 677 . 5 , 537 . 4 , 413 . 2 ; hrms ( esi ) calcd for c 61 h 116 o 7 si 4 na 1095 . 7696 [ m + na ] + , found 1095 . 7712 ; [ α ] 20 d + 4 . 8 ( c 1 . 7 , chcl 3 ). the procedure for 46 was used with 75 ( 0 . 42 g , 0 . 39 μmol ), dess - martin reagent ( 0 . 25 g , 0 . 59 mmol ) and bis ( 2 , 2 , 2 - trifluoroethyl )-( methoxycarbonylmethyl ) phosphate ( 0 . 10 ml , 0 . 47 μmol ), 18 - crown - 6 ( 0 . 52 g , 1 . 97 mmol ) and khmds ( 0 . 94 ml , 0 . 47 mmol ) to yield 76 ( 0 . 38 g , 86 % for 2 steps ) by flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2955 , 2856 , 1722 , 1640 , 1514 , 1462 , 1250 , 1174 , 1084 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 44 ( dd , j = 15 . 3 , 11 . 3 hz , 1h ), 7 . 31 - 7 . 29 ( m , 2h ), 6 . 90 - 6 . 87 ( m , 2h ), 6 . 04 ( t , j = 11 . 0 hz , 1h ), 6 . 02 ( m , 1h ), 5 . 66 - 5 . 60 ( m , 2h ), 5 . 44 ( t , j = 10 . 0 hz , 1h ), 5 . 30 ( dd , j = 11 . 1 , 8 . 3 hz , 1h ), 5 . 20 ( d , j = 16 . 8 hz , 1h ), 5 . 12 ( d , j = 10 . 2 hz , 1h ), 4 . 61 - 4 . 51 ( m , 3h ), 3 . 98 ( m , 1h ), 3 . 80 ( s , 3h ), 3 . 73 ( s , 3h ), 3 . 68 ( m , 1h ), 3 . 42 ( m , 1h ), 3 . 37 ( dd , j = 7 . 6 , 3 . 1 hz , 1h ), 3 . 03 ( m , 1h ), 2 . 60 ( m , 2h ), 1 . 72 ( m , 2h ), 1 . 61 - 1 . 41 ( m , 1h ), 1 . 38 - 1 . 27 ( m , 3h ), 1 . 20 - 1 . 15 ( m , 2h ), 1 . 14 ( d , j = 6 . 7 hz , 3h ), 1 . 08 ( d , j = 6 . 8 hz , 3h ), 1 . 01 ( d , j = 6 . 6 hz , 3h ), 1 . 00 ( d , j = 6 . 7 hz , 3h ), 0 . 99 - 0 . 87 ( m , 39h ), 0 . 16 - 0 . 07 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 7 , 159 . 0 , 147 . 1 , 145 . 4 , 134 . 5 , 132 . 6 , 132 . 3 , 131 . 3 , 129 . 0 , 128 . 9 , 126 . 8 , 117 . 1 , 115 . 4 , 113 . 6 , 84 . 3 , 80 . 2 , 75 . 0 , 72 . 5 , 72 . 1 , 66 . 4 , 55 . 1 , 50 . 8 , 43 . 4 , 42 . 4 , 40 . 6 , 37 . 9 , 35 . 9 , 35 . 2 , 33 . 9 , 28 . 1 , 26 . 2 , 26 . 0 , 25 . 90 , 25 . 87 , 25 . 6 , 19 . 3 , 18 . 8 , 18 . 4 , 18 . 1 , 18 . 05 , 18 . 04 , 14 . 6 , 13 . 3 , 9 . 3 , − 3 . 0 , − 3 . 5 , − 3 . 7 , − 3 . 8 , − 4 . 2 , − 4 . 3 , − 4 . 4 , − 4 . 5 ; lrms ( esi ) 1149 . 7 [ m + na ] + , 995 . 7 , 436 . 2 ; hrms ( esi ) calcd for c 64 h 118 o 8 si 4 na 1149 . 7802 [ m + na ] + , found 1149 . 7813 ; [ α ] 20 d − 3 . 8 ( c 0 . 85 , chcl 3 ). the procedure for 47 was used with 76 ( 0 . 38 g , 0 . 34 μmol ) and ddq ( 0 . 084 g , 0 . 37 mmol ) to yield 77 ( 0 . 28 g , 82 %) after flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 3542 , 2956 , 2856 , 1722 , 1640 , 1462 , 1254 , 1175 , 1086 , 1004 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 39 ( dd , j = 15 . 2 , 11 . 2 hz , 1h ), 6 . 63 ( ddd , j = 16 . 9 , 10 . 5 , 10 . 4 hz , 1h ), 6 . 53 ( t , j = 11 . 3 hz , 1h ), 6 . 09 ( t , j = 1 . 0 hz , 1h ), 5 . 98 ( dd , j = 8 . 3 , 7 . 1 hz , 1h ), 5 . 58 ( d , j = 11 . 3 hz , 1h ), 5 . 45 - 5 . 39 ( m , 2h ), 5 . 26 ( dd , j = 10 . 8 , 8 . 4 hz , 1h ), 5 . 20 ( d , j = 16 . 9 hz , 1h ), 5 . 11 ( d , j = 10 . 1 hz , 1h ), 4 . 53 ( m , 1h ), 3 . 95 ( m , 1h ), 3 . 76 ( m , 1h ), 3 . 71 ( s , 3h ), 3 . 47 ( m , 1h ), 3 . 40 ( m , 1h ), 2 . 82 ( m , 1h ), 2 . 55 ( m , 1h ), 2 . 20 ( br , 1h ), 1 . 72 ( m , 2h ), 1 . 60 - 1 . 35 ( m , 5h ), 1 . 32 - 1 . 10 ( m , 5h ), 1 . 04 ( d , j = 6 . 8 hz , 3h ), 0 . 99 - 0 . 83 ( m , 48h ), 0 . 12 - 0 . 03 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 7 , 147 . 1 , 145 . 4 , 135 . 2 , 132 . 6 , 132 . 5 , 132 . 3 , 130 . 0 , 126 . 8 , 117 . 7 , 115 . 5 , 80 . 2 , 77 . 3 , 76 . 2 , 72 . 1 , 66 . 5 , 50 . 9 , 43 . 4 , 42 . 5 , 38 . 3 , 38 . 1 , 36 . 1 , 35 . 8 , 34 . 7 , 33 . 7 , 28 . 3 , 26 . 2 , 25 . 94 , 25 . 89 , 25 . 5 , 19 . 5 , 18 . 4 , 18 . 1 , 17 . 7 , 14 . 9 , 13 . 3 , 7 . 2 , − 3 . 0 , − 3 . 6 , − 3 . 8 , − 4 . 18 , − 4 . 20 , − 4 . 37 , − 4 . 41 ; lrms ( esi ) 1029 . 7 [ m + na ] + , 875 . 6 , 379 . 3 ; hrms ( esi ) calcd for c 56 h 110 o 7 si 4 na 1029 . 7226 [ m + na ] + , found 1029 . 7244 ; [ α ] 20 d − 18 . 7 ( c 0 . 62 , chcl 3 ). the procedure for 48 was used with 77 ( 0 . 28 g , 0 . 28 μmol ) and in koh ( 2 . 8 ml , 2 . 8 mmol ) to yield the acid ( 0 . 27 g , quantitative ) as a pale yellow oil , which was used directly in next step : ir ( chcl 3 ) 2930 , 1693 , 1635 , 1462 , 1387 , 1255 , 1089 , 838 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 36 ( dd , j = 15 . 0 , 11 . 4 hz , 1h ), 6 . 6 - 6 . 57 ( m , 2h ), 6 . 08 ( t , j = 10 . 9 hz , 1h ), 6 . 02 ( dd , j = 15 . 7 , 7 . 0 hz , 1h ), 5 . 59 ( d , j = 11 . 3 hz , 1h ), 5 . 45 - 5 . 39 ( m , 2h ), 5 . 26 ( m , 1h ), 5 . 20 ( d , j = 17 . 8 hz , 1h ), 5 . 11 ( d , j = 10 . 2 hz , 1h ), 4 . 55 ( m , 1h ), 3 . 95 ( m , 1h ), 3 . 76 ( m , 1h ), 3 . 49 ( m , 1h ), 3 . 41 ( m , 1h ), 2 . 82 ( m , 1h ), 2 . 57 ( m , 2h ), 1 . 70 ( m , 2h ), 1 . 57 - 1 . 41 ( m , 5h ), 1 . 31 - 1 . 12 ( m , 5h ), 1 . 04 ( d , j = 6 . 7 hz , 3h ), 0 . 99 - 0 . 84 ( m , 48h ), 0 . 12 - 0 . 04 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 170 . 9 , 147 . 7 , 146 . 8 , 134 . 9 , 132 . 5 , 132 . 4 , 132 . 2 , 130 . 0 , 126 . 9 , 117 . 6 , 115 . 5 , 80 . 1 , 75 . 7 , 72 . 0 , 66 . 4 , 58 . 1 , 43 . 4 , 42 . 5 , 38 . 3 , 38 . 1 , 35 . 9 , 35 . 6 , 34 . 7 , 33 . 5 , 28 . 3 , 26 . 2 , 25 . 90 , 25 . 85 , 25 . 5 , 25 . 1 , 19 . 5 , 18 . 4 , 18 . 1 , 18 . 0 , 17 . 7 , 14 . 9 , 13 . 3 , 7 . 3 , − 3 . 1 , − 3 . 7 , − 3 . 8 , − 3 . 9 , − 4 . 2 , − 4 . 3 , − 4 . 4 , − 4 . 5 ; lrms ( esi ) 1015 . 7 [ m + na ] + , 861 . 6 , 729 . 5 , 651 . 4 ; hrms ( esi ) calcd for c 55 h 108 o 7 si 4 na 1015 . 7070 [ m + na ] + , found 1015 . 7091 ; [ α ] 20 d − 14 . 6 ( c 1 . 4 , chcl 3 ). the procedure for 49 was used with the acid ( 0 . 26 g , 0 . 26 μmol ), 2 , 4 , 6 - trichlorobenzoyl chloride ( 0 . 21 ml , 1 . 30 mmol ), et 3 n ( 0 . 22 ml , 1 . 56 mmol ) and 4 - dmap ( 130 ml , 2 . 6 mmol ) to yield 78 ( 0 . 19 g , 76 % for 2 steps ) by flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2856 , 1714 , 1640 , 1471 , 1255 , 1088 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 16 ( dd , j = 15 . 6 , 11 . 2 hz , 1h ), 6 . 61 ( ddd , j = 16 . 8 , 10 . 6 , 10 . 5 hz ; 1h ), 6 . 52 ( t , j = 11 . 3 hz , 1h ), 6 . 03 ( d , j = 9 . 6 , 5 . 9 hz , 1h ), 6 . 00 ( t , j = 10 . 6 hz , 1h ), 5 . 62 ( t , j = 10 . 5 hz , 1h ), 5 . 56 ( d , j = 11 . 3 hz , 1h ), 5 . 39 ( t , j = 10 . 5 hz , 1h ), 5 . 28 ( dd , j = 11 . 2 , 8 . 0 hz , 1h ), 5 . 20 - 5 . 14 ( m , 2h ), 5 . 09 ( d , j = 10 . 3 hz , 1h ), 4 . 59 ( m , 1h ), 4 . 01 ( m , 1h ), 3 . 53 ( m , 1h ), 3 . 43 ( m , 1h ), 3 . 06 ( m , 1h ), 2 . 56 ( m , 1h ), 2 . 45 ( m , 1h ), 1 . 90 ( m , 1h ), 1 . 55 - 1 . 35 ( m , 6h ), 1 . 28 ( m , 1h ), 1 . 24 - 1 . 12 ( m , 4h ), 1 . 08 ( d , j = 6 . 7 hz , 3h ), 1 . 02 ( d , j = 5 . 9 hz , 3h ), 1 . 01 ( d , j = 6 . 0 hz , 3h ), 0 . 93 - 0 . 88 ( m , 39h ), 0 . 81 ( d , j = 6 . 9 hz , 3h ), 0 . 14 - 0 . 05 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 2 , 144 . 1 , 142 . 6 , 133 . 9 , 132 . 1 , 131 . 5 , 129 . 7 , 128 . 0 , 127 . 5 , 117 . 8 , 117 . 6 , 80 . 3 , 74 . 0 , 71 . 2 , 66 . 5 , 62 . 4 , 43 . 7 , 39 . 8 , 39 . 3 , 34 . 9 , 34 . 0 , 33 . 0 , 31 . 8 , 27 . 8 , 26 . 1 , 26 . 05 , 25 . 98 , 20 . 1 , 18 . 33 , 18 . 28 , 18 . 14 , 18 . 11 , 17 . 8 , 16 . 1 , 14 . 0 , 10 . 7 , − 2 . 7 , − 3 . 8 , − 4 . 0 , − 4 . 1 , − 4 . 2 , − 4 . 3 ; lrms ( esi ) 997 . 7 [ m + na ] + , 843 . 6 , 711 . 5 , 579 . 4 ; hrms ( esi ) calcd for c 55 h 106 o 6 si 4 na 997 . 6964 [ m + na ] + , found 997 . 6989 ; [ α ] 20 d − 26 . 4 ( c 0 . 59 , chcl 3 ). the procedure for 1 was used with 78 ( 0 . 19 g , 0 . 19 μmol ), 3n hcl in 15 ml of 2 : 1 meoh / thf to yield 79 ( 25 mg , 24 %) after flash column chromatography ( etoac / hexane 3 : 7 ) as a colorless oil : ir ( chcl 3 ) 3414 , 2965 , 2930 , 1708 , 1637 , 1454 , 1375 , 1273 , 1182 , 1046 , 968 cm − 1 ; 1 h nmr ( 600 mhz , cd 3 od ) 6 7 . 22 ( dd , j = 15 . 4 , 11 . 2 hz , 1h ), 6 . 67 ( ddd , j = 17 . 3 , 11 . 0 , 10 . 5 hz , 1h ), 6 . 64 ( dd , j = 11 . 4 , 11 . 4 hz , 1h ), 6 . 07 ( dd , j = 15 . 4 , 7 . 7 hz , 1h ), 6 . 02 ( dd , j = 10 . 9 , 10 . 9 hz , 1h ), 5 . 55 ( t , j = 10 . 6 hz , 1h ), 5 . 52 ( d , j = 11 . 4 hz , 1h ), 5 . 43 ( dd , j = 10 . 9 , 9 . 0 hz , 1h ), 5 . 35 ( dd , j = 10 . 7 , 10 . 6 hz , 1h ), 5 . 20 ( d , j = 16 . 7 hz , 1h ), 5 . 12 ( d , j = 10 . 2 hz , 1h ), 5 . 08 ( dd , j = 5 . 9 , 5 . 9 hz , 1h ), 4 . 64 ( m , 1h ), 3 . 86 ( ddd , j = 8 . 4 , 4 . 7 , 4 . 5 hz , 1h ), 3 . 43 ( m , 1h ), 3 . 16 ( m , 1h ), 3 . 14 ( dd , j = 8 . 1 , 2 . 6 hz , 1h ), 2 . 73 ( m , 1h ), 2 . 37 ( m , 1h ), 1 . 84 ( m , 1h ), 1 . 68 ( m , 1h ), 1 . 51 - 1 . 45 ( m , 3h ), 1 . 31 ( m , 1h ), 1 . 20 ( m , 1h ), 1 . 14 - 1 . 11 ( m , 1h ), 1 . 08 ( d , j = 6 . 9 hz , 6h ), 1 . 07 - 1 . 01 ( m , 2h ), 0 . 99 ( d , j = 6 . 8 hz , 3h ), 0 . 98 ( d , j = 6 . 7 hz , 3h ), 0 . 95 ( m , 1h ), 0 . 92 ( d , j = 6 . 6 hz , 3h ); 13 c nmr ( 150 mhz , cd 3 od ) δ 168 . 2 , 146 . 6 , 144 . 8 , 134 . 3 , 133 . 8 , 133 . 4 , 132 . 2 , 131 . 3 , 129 . 1 , 118 . 5 , 118 . 0 , 79 . 9 , 79 . 3 , 72 . 4 , 71 . 0 , 65 . 5 , 44 . 9 , 41 . 7 , 40 . 7 , 37 . 9 , 36 . 0 , 35 . 4 , 35 . 2 , 33 . 9 , 27 . 4 , 27 . 2 , 19 . 5 , 18 . 3 , 16 . 4 , 15 . 1 , 10 . 1 ; lrms ( esi ) 541 . 3 [ m + na ] + , 483 . 3 ; hrms ( esi ) calcd for c 31 h 50 o 6 na 541 . 3505 [ m + na ] + , found 541 . 3521 ; [ α ] 20 d − 34 . 4 ( c 0 . 18 , meoh ). ( 3s , 4s , e )- 3 -( tert - butyldimethylsilyloxy )- 4 - methyl - 7 - trityloxyhept - 5 - en - 1 - ol ( 0 . 34 g , 0 . 66 mmol ) in ch 2 cl 2 ( 10 ml ) was treated with dess - martin periodinane ( 0 . 41 g , 0 . 99 mmol ). after 1 h , the mixture was quenched with saturated nahco 3 ( 10 ml ). the aqueous layer was extracted with ethyl ether ( 10 ml × 2 ) and the combined extracts were dried over anhydrous mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 8 : 2 ) to remove the dess - martin residue provided the aldehyde as a colorless oil , which was used for the next reaction without further purification . a solution of the above aldehyde in thf ( 10 ml ) and h 2 o ( 5 ml ) was treated with a 2 m solution of 2 - methyl - 2 - butene ( 1 . 9 ml , 0 . 95 mmol ) in thf , nah 2 po 4 . h 2 o ( 0 . 27 g , 1 . 96 mmol ) and naclo 2 ( 0 . 22 g , 1 . 96 mmol ). the reaction mixture was stirred for 2 h , diluted with in hcl ( 20 ml ) and extracted with ch 2 cl 2 ( 2 × 40 ml ). the combined organic layers were dried over mgso 4 , concentrated in vacuo and the crude was used for the next reaction without further purification . to a solution of acid in ch 2 cl 2 , n , o - dimethylhydroxylamine hydrochloride ( 0 . 064 g , 0 . 65 mmol ), et 3 n ( 0 . 09 ml , 0 . 65 mmol ), dmap ( 8 mg , 0 . 065 mmol ) were successively added . the reaction mixture was cooled to 0 ° c ., dcc ( 0 . 14 g , 0 . 65 mmol ) was added . the mixture was stirred at ambient temperature for 15 h and filtered . the filtrate was washed with 0 . 5 n hcl , saturated aqueous nahco 3 , and brine , dried over anhydrous mgso 4 and concentrated . purification by column chromatography over silica gel ( hexane / etoac 4 : 1 ) gave the weinreb amide 81 ( 0 . 37 g , 81 % for 3 steps ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2855 , 1661 , 1448 , 1385 , 1251 , 1089 , 1054 , 1003 , 836 , 775 , 706 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 64 - 7 . 61 . m , 6h ), 7 . 45 - 7 . 33 ( m , 9h ), 6 . 09 ( dd , j = 15 . 7 , 6 . 6 hz , 1h ), 5 . 75 ( dt , j = 15 . 7 , 5 . 2 hz , 1h ), 4 . 42 ( m , 1h ), 3 . 76 ( s , 3h ), 3 . 70 ( m , 2h ), 3 . 29 ( s , 3h ), 2 . 88 ( m , 1h ), 2 . 55 ( m , 2h ), 1 . 18 ( d , j = 6 . 8 hz , 3h ), 1 . 06 ( s , 9h ), 0 . 27 ( s , 3h ), 0 . 20 ( s , 3h ) ; 13 c nmr ( 75 mhz , cdcl 3 ) δ 172 . 5 , 144 . 2 , 133 . 5 , 128 . 5 , 127 . 6 , 126 . 8 , 86 . 5 , 72 . 8 , 64 . 6 , 61 . 1 , 42 . 2 , 36 . 0 , 31 . 9 , 25 . 8 , 18 . 0 , 14 . 8 , − 4 . 7 , − 4 . 8 ; lrms ( el ) 573 , 558 , 516 , 246 , 165 ; hrms ( ei ) calcd for c 35 h 47 o 4 n 1 si 1 573 . 3290 , found 573 . 3290 ; [ α ] 20 d − 40 . 1 ( c 1 . 2 , chcl 3 ). alkyne 80 ( 7 . 75 g , 18 . 5 mmol ) was taken up in thf ( 185 ml ) and cooled to − 78 ° c . n - buli ( 11 . 6 ml , 1 . 6 m solution in hexane ) was added slowly . after 5 min , the mixture was warmed to 0 ° c . and stirred for 30 min . the mixture was then cooled to − 78 ° c . and amide 81 ( 5 . 31 g , 9 . 26 mmol ) in thf ( 15 ml ) was added slowly . after 5 min the solution was warmed to 0 ° c . and stirred for 1 h . the reaction was quenched with aq nh 4 cl and the mixture was partitioned in a separatory funnel . the aqueous phase was extracted with ether ( 50 ml × 3 ) and combined organic extracts were washed with brine and dried over mgso 4 . filtration and concentration under reduced pressure , followed by flash chromatography on silica gel ( hexane / etoac 95 : 5 ) afforded ynone ( 8 . 45 g , 98 %) as a pale yellow oil : ir ( chcl 3 ) 2955 , 2929 , 2856 , 2208 , 1674 , 1514 , 1470 , 1249 , 1092 , 836 , 775 , 706 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ7 . 50 - 7 . 47 . m , 6h ), 7 . 35 - 7 . 22 ( m , 1h ), 6 . 88 - 6 . 84 ( m , 2h ), 5 . 81 ( dd , j = 15 . 6 , 6 . 7 hz , 1h ), 5 . 58 ( dt , j = 15 . 6 , 5 . 2 hz , 1h ), 4 . 64 ( d , j = 10 . 8 hz , 1h ), 4 . 54 ( d , j = 10 . 8 hz , 1h ), 4 . 27 ( m , 1h ), 3 . 80 ( s , 3h ), 3 . 59 ( d , j = 5 . 2 hz , 2h ), 3 . 44 - 3 . 34 ( m , 2h ), 3 . 18 ( t , j = 5 . 4 hz , 1h ), 2 . 94 ( m , 1h ), 2 . 62 ( m , 1h ), 2 . 38 ( m , 1h ), 1 . 89 ( m , 1h ), 1 . 68 ( m , 1h ), 1 . 26 ( d , j = 7 . 0 hz , 3h ), 1 . 24 ( m , 1h ), 0 . 99 ( d , j = 6 . 9 hz , 3h ), 0 . 97 ( d , j = 6 . 9 hz , 3h ), 0 . 92 ( s , 9h ), 0 . 91 ( m , 1h ), 0 . 89 ( s , 9h ), 0 . 84 ( d , j = 6 . 7 hz , 3h ), 0 . 09 - 0 . 05 ( m , 12h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 186 . 4 , 159 . 1 , 144 . 3 , 133 . 5 , 130 . 7 , 129 . 2 , 128 . 7 , 127 . 7 , 127 . 3 , 126 . 9 , 113 . 7 , 96 . 8 , 86 . 8 , 86 . 2 , 82 . 6 , 74 . 0 , 72 . 3 , 69 . 2 , 64 . 9 , 55 . 2 , 50 . 5 , 42 . 3 , 34 . 9 , 33 . 2 , 33 . 0 , 29 . 5 , 26 . 0 , 25 . 9 , 18 . 3 , 18 . 1 , 17 . 2 , 16 . 3 , 15 . 9 , 14 . 8 , − 4 . 50 , − 4 . 55 , − 5 . 3 ; lrms ( esi ) 953 . 6 [ m + na ]+, 855 . 4 , 797 . 4 , 577 . 5 , 413 . 4 , 359 . 3 , 328 . 4 ; hrms ( esi ) calcd for c 58 h 82 o 6 si 2 na 953 . 5548 [ m + na ]+, found 953 . 5552 ; [ α ] 20 d − 9 . 5 ( c 2 . 8 , chcl 3 ). ynone 82 ( 7 . 06 g , 7 . 59 mmol ) was taken up in i - proh ( 100 ml ). noyori catalyst ( 1 . 02 g , 1 . 52 mmol , 20 mol %) was added in one portion and the solution was stirred for 12 h . the solvent was removed under vacuum , and the crude residue was purified by flash chromatography on silica gel ( hexane / etoac 9 : 1 ), affording propargylic alcohol 83 ( 6 . 16 g , 87 %) as a pale yellow oil : ir ( chcl 3 ) 3434 , 2955 , 2928 , 2855 , 1613 , 1513 , 1462 , 1250 , 1091 , 836 , 775 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 59 - 7 . 57 ( m , 6h ), 7 . 42 - 7 . 30 ( m , 11h ), 6 . 96 - 6 . 93 ( m , 2h ), 5 . 96 ( dd , j = 15 . 7 , 6 . 4 hz , 1h ), 5 . 68 ( dt , j = 15 . 2 , 5 . 3 hz , 1h ), 4 . 79 ( d , j = 10 . 8 hz , 1h ), 4 . 67 ( m , 1h ), 4 . 63 ( d , j = 10 . 9 hz , 1h ), 4 . 07 ( m , 1h ), 3 . 86 ( s , 3h ), 3 . 69 ( d , j = 4 . 7 hz , 2h ), 3 . 49 ( m , 2h ), 3 . 22 ( t , j = 5 . 5 hz , 1h ), 2 . 91 ( m , 1h ), 2 . 67 ( d , j = 5 . 3 hz , 1h ), 2 . 56 ( m , 1h ), 1 . 98 ( m , 1h ), 1 . 86 ( m , 2h ), 1 . 77 ( m , 1h ), 1 . 36 ( m , 1h ), 1 . 31 ( d , j = 7 . 0 hz , 3h ), 1 . 09 ( d , j = 7 . 1 hz , 3h ), 1 . 06 ( d , j = 7 . 1 hz , 3h ), 1 . 03 ( s , 9h ), 1 . 02 ( s , 9h ), 0 . 94 ( d , j = 6 . 6 hz , 3h ), 0 . 24 ( s , 3h ), 0 . 22 ( s , 3h ), 0 . 15 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 158 . 9 , 144 . 3 , 133 . 2 , 131 . 0 , 129 . 1 , 128 . 6 , 127 . 7 , 127 . 0 , 126 . 8 , 113 . 5 , 87 . 5 , 86 . 79 , 86 . 74 , 82 . 6 , 74 . 0 , 73 . 3 , 69 . 3 , 65 . 0 , 59 . 6 , 55 . 1 , 41 . 4 , 40 . 2 , 34 . 5 , 33 . 1 , 32 . 7 , 29 . 1 , 25 . 9 , 18 . 3 , 18 . 0 , 17 . 9 , 16 . 6 , 15 . 8 , 15 . 3 , − 4 . 3 , − 4 . 5 , − 5 . 4 ; lrms ( esi ) 955 . 6 [ m + na ]+, 707 . 3 , 633 . 3 , 559 . 2 , 413 . 3 ; hrms ( esi ) calcd for c 58 h 84 o 6 si 2 na 955 . 5704 [ m + na ]+, found 955 . 5734 ; [ α ] 20 d − 8 . 5 ( c 1 . 5 , chcl 3 ). a catalytic amount of lindlar catalyst ( ca . 200 mg ) was added to a solution of alcohol 83 ( 3 . 11 g , 3 . 33 mmol ) in toluene ( 100 ml ). the flask was fitted with a h 2 balloon , and stirred under an atmosphere of h 2 until starting material was consumed ( usually 1 h ), as indicated by tlc analysis . the mixture was filtered through a pad of celite and concentrated under reduced pressure to afford the olefin 84 as a colorless oil ( 2 . 81 g , 90 %): ir ( chcl 3 ) 3434 , 2956 , 2928 , 2856 , 1613 , 1514 , 1471 , 1249 , 1062 , 836 , 774 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 58 - 7 . 55 ( m , 6h ), 7 . 4 - 7 . 29 ( m , 1h ), 6 . 93 ( m , 2h ), 5 . 90 ( dd , j = 15 . 6 , 6 . 6 hz , 1h ), 5 . 68 ( dt , j = 15 . 7 , 5 . 4 hz , 1h ), 5 . 60 ( dd , j = 11 . 1 , 8 . 9 hz , 1h ), 5 . 51 ( dd , j = 11 . 2 , 7 . 3 hz , 1h ), 4 . 66 ( m , 1h ), 4 . 58 ( d , j = 10 . 9 hz , 1h ), 4 . 55 ( d , j = 10 . 9 hz , 1h ), 3 . 95 ( m , 1h ), 3 . 86 ( s , 3h ), 3 . 66 ( dd , j = 4 . 9 hz , 1h ), 3 . 52 - 3 . 38 ( m , 2h ), 3 . 01 ( m , 2h ), 2 . 89 ( br , 1h ), 2 . 55 ( m , 1h ), 1 . 79 ( m , 1h ), 1 . 70 ( m , 1h ), 1 . 62 ( m , 2h ), 1 . 33 - 1 . 29 ( m , 2h ), 1 . 12 ( d , j = 5 . 8 hz , 3h ), 1 . 10 ( d , j = 6 . 7 hz , 3h ), 1 . 02 ( s , 9h ), 1 . 01 ( s , 9h ), 0 . 89 ( d , j = 6 . 1 hz , 3h ), 0 . 87 ( d , j = 6 . 3 hz , 3h ), 0 . 19 ( s , 6h ), 0 . 14 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 158 . 9 , 144 . 3 , 134 . 1 , 133 . 5 , 132 . 6 , 131 . 0 , 129 . 0 , 128 . 6 , 127 . 7 , 126 . 8 , 126 . 7 , 113 . 5 , 88 . 4 , 86 . 7 , 74 . 9 , 73 . 5 , 69 . 4 , 65 . 2 , 65 . 1 , 55 . 1 , 41 . 8 , 40 . 2 , 35 . 0 , 34 . 6 , 33 . 1 , 25 . 9 , 19 . 1 , 18 . 3 , 18 . 0 , 16 . 6 , 15 . 8 , 15 . 6 , − 4 . 4 , − 4 . 5 , − 5 . 3 ; lrms ( esi ) 957 . 6 [ m + na ]+, 781 . 4 , 707 . 3 , 559 . 3 , 485 . 2 , 413 . 4 ; hrms ( esi ) calcd for c 58 h 86 o 6 si 2 na 957 . 5861 [ m + na ]+, found 957 . 5900 ; [ α ] 20 d + 2 . 0 ( c 1 . 2 , chcl 3 ). tbsotf ( 1 . 05 ml , 4 . 57 mmol ) was added to a stirred solution of the alcohol 84 ( 3 . 89 g , 4 . 16 mmol ) and 2 , 6 - lutidine ( 0 . 58 ml , 5 . 01 mmol ) in ch 2 cl 2 ( 14 ml ) at 0 ° c . after stirring for 1 h at 0 ° c ., the reaction mixture was quenched by the addition of water ( 25 ml ), and extracted by ch 2 cl 2 and dried over mgso 4 , followed by the evaporation of the solvent under reduced pressure . the residue was purified by short column chromatography ( hexane / etoac 9 : 1 ) to obtain the product 85 ( 4 . 36 g , quantitative ) as a colorless oil : ir ( chcl 3 ) 2956 , 2928 , 2856 , 1613 , 1514 , 1471 , 1462 , 1250 , 1088 , 836 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 61 - 7 . 58 ( m , 6h ), 7 . 43 - 7 . 31 ( m , 1h ), 6 . 97 - 6 . 94 ( m , 2h ), 5 . 95 ( dd , j = 15 . 7 , 6 . 0 hz , 1h ), 5 . 67 ( dt , j = 15 . 7 , 5 . 6 hz , 1h ), 5 . 62 - 5 . 46 ( m , 2h ), 4 . 71 ( m , 1h ), 4 . 62 ( m , 2h ), 4 . 05 ( m , 1h ), 3 . 87 ( s , 3h ), 3 . 69 ( d , j = 5 . 3 hz , 2h ), 3 . 53 - 3 . 40 ( m , 2h ), 3 . 08 ( m , 1h ), 2 . 91 ( m , 1h ), 2 . 51 ( m , 1h ), 1 . 76 ( m , 1h ), 1 . 66 ( m , 2h ), 1 . 50 - 1 . 40 ( m , 2h ), 1 . 32 ( m , 1h ), 1 . 22 ( d , j = 6 . 8 hz , 6h ), 1 . 09 ( d , j = 6 . 9 hz , 3h ), 1 . 06 - 0 . 96 ( m , 27h ), 0 . 91 ( d , j = 6 . 6 hz , 3h ), 0 . 83 ( d , j = 6 . 5 hz , 3h ), 0 . 25 - 0 . 17 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 158 . 9 , 144 . 4 , 134 . 3 , 133 . 7 , 131 . 4 , 129 . 4 , 129 . 0 , 128 . 6 , 127 . 7 , 126 . 8 , 126 . 4 , 113 . 5 , 88 . 8 , 86 . 7 , 74 . 8 , 72 . 8 , 69 . 5 , 66 . 3 , 65 . 1 , 55 . 1 , 43 . 0 , 42 . 3 , 35 . 4 , 35 . 1 , 33 . 4 , 33 . 1 , 26 . 1 , 26 . 0 , 18 . 8 , 18 . 3 , 18 . 1 , 16 . 7 , 15 . 7 , 14 . 6 , − 2 . 8 , − 3 . 9 , − 4 . 1 , − 4 . 2 , − 5 . 3 ; lrms ( esi ) 1071 . 9 [ m + na ]+, 413 . 4 , 359 . 3 , 243 . 2 ; hrms ( esi ) calcd for c 64 h 100 o 6 si 3 na 1071 . 6725 [ m + na ]+, found 1071 . 6779 ; [ α ] 20 d − 9 . 5 ( c 3 . 0 , chcl 3 ). the above pmb alcohol 85 ( 2 . 90 g , 2 . 77 mmol ) was added to ch 2 cl 2 ( 25 ml ) and h 2 o ( 1 ml ), and ddq ( 0 . 94 g , 4 . 15 μmol ) was added . after 1 h of stirring , the reaction mixture was quenched by adding sat &# 39 ; d nahco 3 ( 200 ml ). the organic phase was washed by sat &# 39 ; d nahco 3 solution ( 3 × 100 ml ) and brine , dried over mgso 4 and concentrated . purification by flash column chromatography ( etoac / hexane 5 : 95 ) furnished 86 ( 2 . 16 g , 84 %) as a colorless oil : ir ( chcl 3 ) 3477 , 2956 , 2928 , 2856 , 1471 , 1386 , 1254 , 1088 , 836 , 774 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 55 - 7 . 52 ( m , 6h ), 7 . 38 - 7 . 25 ( m , 9h ), 5 . 92 ( dd , j = 15 . 7 , 6 . 0 hz , 1h ), 5 . 62 ( dt , j = 15 . 7 , 5 . 5 hz , 1h ), 5 . 52 ( dd , j = 11 . 1 , 9 . 3 hz , 1h ), 5 . 35 ( t , j = 10 . 5 hz , 1h ), 4 . 63 ( m , 1h ), 3 . 97 ( m , 1h ), 3 . 63 ( d , j = 5 . 4 hz , 2h ), 3 . 51 - 3 . 36 ( m , 2h ), 3 . 18 ( m , 1h ), 2 . 68 ( m , 1h ), 2 . 47 ( m , 1h ), 1 . 71 - 1 . 59 ( m , 3h ), 1 . 42 - 1 . 27 ( m , 2h ), 1 . 17 ( m , 1h ), 1 . 08 ( d , j = 6 . 7 hz , 3h ), 1 . 04 ( d , j = 6 . 9 hz , 3h ), 0 . 99 ( s , 9h ), 0 . 97 ( s , 9h ), 0 . 96 ( s , 9h ), 0 . 91 ( d , j = 6 . 8 hz , 3h ), 0 . 84 ( d , j = 6 . 6 hz , 3h ), 0 . 18 ( s , 3h ), 0 . 16 ( s , 3h ), 0 . 15 ( s , 3h ), 0 . 13 ( s , 3h ), 0 . 12 ( s , 6h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 4 , 135 . 2 , 134 . 1 , 131 . 1 , 128 . 7 , 127 . 7 , 126 . 8 , 126 . 4 , 86 . 7 , 79 . 8 , 72 . 8 , 69 . 6 , 66 . 2 , 65 . 2 , 43 . 0 , 42 . 1 , 35 . 5 , 33 . 7 , 32 . 8 , 32 . 5 , 26 . 1 , 26 . 0 , 25 . 9 , 18 . 4 , 18 . 1 , 17 . 6 , 16 . 8 , 16 . 3 , 14 . 7 , − 2 . 9 , − 4 . 0 , − 4 . 15 , − 4 . 22 , − 5 . 3 ; lrms ( esi ) 951 . 7 [ m + na ]+, 823 . 7 , 577 . 4 , 413 . 3 , 328 . 4 , 243 . 1 ; hrms ( esi ) calcd for c 56 h 92 o 5 si 3 na 951 . 6150 [ m + na ]+, found 951 . 6165 ; [ α ] 20 d 30 . 0 ( c 3 . 6 , chcl 3 ). the procedure for 85 was used with above 86 ( 3 . 34 g , 3 . 60 μmol ), tbsotf ( 1 . 82 ml , 7 . 9 mmol ) to yield 3 . 53 g ( 94 %) of the product by flash column chromatography ( etoac / hexane 5 : 95 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2928 , 2856 , 1471 , 1462 , 1361 , 1254 , 1088 , 836 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 50 - 7 . 48 ( m , 6h ), 7 . 34 - 7 . 22 ( m , 9h ), 5 . 82 ( dd , j = 15 . 7 , 6 . 0 hz , 1h ), 5 . 57 ( dt , j = 15 . 8 , 5 . 9 hz , 1h ), 5 . 48 ( dd , j = 11 . 0 , 9 . 9 hz , 1h ), 5 . 32 ( dd , j = 11 . 0 , 8 . 7 hz , 1h ), 4 . 56 ( m , 1h ), 3 . 93 ( m , 1h ), 3 . 59 ( d , j = 5 . 5 hz , 2h ), 3 . 39 ( dd , j = 9 . 6 , 5 . 8 hz , 1h ), 3 . 31 - 3 . 27 ( m , 2h ), 2 . 62 ( m , 1h ), 2 . 40 ( m , 1h ), 1 . 58 - 1 . 50 ( m , 3h ), 1 . 35 ( m , 1h ), 1 . 20 - 1 . 09 ( m , 2h ), 1 . 02 ( d , j = 7 . 1 hz , 3h ), 1 . 00 ( d , j = 7 . 0 hz , 3h ), 0 . 94 ( s , 9h ), 0 . 92 ( s , 9h ), 0 . 91 ( s , 9h ), 0 . 90 ( s , 9h ), 0 . 78 ( d , j = 6 . 8 hz , 3h ), 0 . 74 ( d , j = 6 . 6 hz , 3h ), 0 . 13 - 0 . 05 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 4 , 134 . 5 , 133 . 0 , 131 . 8 , 128 . 7 , 127 . 7 , 126 . 8 , 126 . 4 , 86 . 7 , 81 . 2 , 72 . 8 , 69 . 3 , 66 . 6 , 65 . 3 , 43 . 1 , 42 . 3 , 35 . 9 , 35 . 1 , 33 . 3 , 29 . 7 , 26 . 2 , 26 . 1 , 26 . 0 , 19 . 6 , 18 . 4 , 18 . 3 , 18 . 2 , 16 . 3 , 16 . 0 , 14 . 6 , − 2 . 8 , − 3 . 5 , − 3 . 6 , − 4 . 0 , − 4 . 1 , − 5 . 3 ; lrms ( esi ) 1065 . 7 [ m + na ]+, 953 . 7 , 615 . 1 , 577 . 3 , 359 . 2 ; hrms ( esi ) calcd for c 62 h 106 o 5 si 4 na 1065 . 7015 [ m + na ]+, found 1065 . 7068 ; [ α ] 20 d − 22 . 5 ( c 2 . 0 , chcl 3 ). hf - pyridine in pyridine ( 40 ml , prepared by slow addition of 12 ml pyridine to 3 ml hf - pyridine complex followed by dilution with 25 ml thf ) was slowly added to a solution of tbs ether 87 ( 3 . 54 g , 4 . 10 mmol ) in thf ( 5 ml ) at 0 ° c . the mixture was stirred for 2 days at 0 ° c . and quenched with sat &# 39 ; d nahco 3 ( 100 ml ). the aqueous layer was separated and extracted with et 2 o ( 3 × 50 ml ). the combined organic layers were washed with sat &# 39 ; d cuso 4 ( 3 × 50 ml ), dried over mgso 4 , and concentrated . flash column chromatography ( etoac / hexane 15 : 85 ) afforded 2 . 08 g ( 66 %) of the alcohol as a colorless oil : ir ( chcl 3 ) 3400 , 2956 , 2928 , 2856 , 1471 , 1448 , 1254 , 1075 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 52 - 7 . 48 ( m , 6h ), 7 . 36 - 7 . 24 ( m , 9h ), 5 . 87 ( dd , j = 15 . 7 , 5 . 9 hz , 1h ), 5 . 59 ( dt , j = 15 . 7 , 5 . 7 hz , 1h ), 5 . 55 ( dd , j = 10 . 6 , 10 . 4 hz , 1h ), 5 . 33 ( dd , j = 11 . 0 , 8 . 7 hz , 1h ), 4 . 58 ( m , 1h ), 3 . 94 ( m , 1h ), 3 . 60 ( d , j = 5 . 5 hz , 2h ), 3 . 38 - 3 . 32 ( m , 2h ), 3 . 25 ( m , 1h ), 2 . 62 ( m , 1h ), 2 . 45 ( m , 1h ), 1 . 59 ( m , 1h ), 1 . 55 ( m , 1h ), 1 . 47 ( m , 1h ), 1 . 35 ( m , 1h ), 1 . 09 ( m , 1h ), 1 . 04 ( d , j = 7 . 6 hz , 3h ), 1 . 01 ( d , j = 7 . 2 hz , 3h ), 0 . 96 ( s , 9h ), 0 . 94 ( s , 9h ), 0 . 93 ( s , 9h ), 0 . 79 ( d , j = 6 . 8 hz , 3h ), 0 . 75 ( d , j = 6 . 6 hz , 3h ), 0 . 15 ( s , 9h ), 0 . 14 ( s , 3h ), 0 . 10 ( s , 3h ), 0 . 09 ( s , 3h ), 0 . 08 ( s , 3h ), 0 . 07 ( s , 3h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 144 . 4 , 134 . 0 , 132 . 7 , 131 . 3 , 128 . 7 , 127 . 7 , 126 . 8 , 126 . 5 , 86 . 8 , 81 . 0 , 73 . 0 , 69 . 2 , 66 . 5 , 65 . 3 , 42 . 6 , 42 . 2 , 36 . 2 , 35 . 5 , 34 . 6 , 33 . 3 , 26 . 2 , 26 . 1 , 25 . 9 , 20 . 0 , 18 . 4 , 18 . 2 , 18 . 1 , 15 . 7 , 15 . 6 , 14 . 9 , − 2 . 8 , − 3 . 7 , − 3 . 8 , − 4 . 0 , − 4 . 1 , − 4 . 2 ; lrms ( esi ) 951 . 6 [ m + na ]+, 705 . 1 , 631 . 1 , 557 . 0 , 397 . 2 , 381 . 2 , 353 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 56 h 92 o 5 si 3 na 951 . 6150 [ m + na ]+, found 951 . 6158 ; [ α ] 20 d − 33 . 5 ( c 2 . 0 , chcl 3 ). the alcohol 88 ( 2 . 04 g , 2 . 20 μmol ) in ch 2 cl 2 ( 30 ml ) was treated with dess - martin periodinane ( 1 . 40 g , 3 . 30 1mol ). after 1 h , the mixture was quenched with saturated nahco 3 ( 30 ml ) and na 2 s 2 o 3 ( 30 ml ). the aqueous layer was extracted with ethyl ether ( 30 ml × 2 ) and the combined extracts were dried over anhydrous mgso 4 . filtration and concentration followed by short flash column chromatography filtration ( hexane / etoac 4 : 1 ) to remove the residue from the dess - martin reagent provided crude aldehyde as a colorless oil , which was used for the next reaction without further purification . a mixture of ketophosphonate 38 ( 0 . 85 g , 2 . 20 mmol ) and ba ( oh ) 2 ( 0 . 30 g , activated by heating to 100 ° c . for 1 - 2 h before use ) in thf ( 40 ml ) was stirred at room temperature for 30 min . a solution of the above aldehyde in wet thf ( 4 ml + 4 × 1 ml washings , 40 : 1 thf / h 2 o ) was then added . after stirring for 12 h , the reaction mixture was diluted with et 2 o ( 30 ml ) and washed with sat &# 39 ; d nahco 3 ( 50 ml ) and brine ( 50 ml ). the organic solution was dried ( mgso 4 ) and the solvent was evaporated in vacuo . the residue was chromatographed ( hexane / etoac 9 : 1 ) to yield 89 ( 2 . 04 g , 78 % for 2 steps ) as a colorless oil : ir ( chcl 3 ) 2957 , 2929 , 2855 , 1618 , 1518 , 1461 , 1388 , 1251 , 1078 , 1036 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 49 - 7 . 46 ( m , 6h ), 7 . 39 ( m , 2h ), 7 . 33 - 7 . 21 ( m , 9h ), 6 . 89 ( m , 2h ), 6 . 79 ( dd , j = 15 . 7 , 7 . 4 hz , 1h ), 6 . 20 ( d , j = 15 . 6 hz , 1h ), 5 . 85 ( dd , j = 15 . 7 , 5 . 9 hz , 1h ), 5 . 58 ( dt , j = 15 . 7 , 4 . 6 hz , 1h ), 5 . 49 ( dd , j = 11 . 0 , 10 . 4 hz , 1h ), 5 . 46 ( s , 1h ), 5 . 34 ( dd , j = 11 . 1 , 8 . 6 hz , 1h ), 4 . 56 ( m , 1h ), 4 . 12 ( dd , j = 11 . 3 , 4 . 6 hz , 1h ), 3 . 92 ( m , 2h ), 3 . 81 ( s , 3h ), 3 . 57 ( d , j = 5 . 6 hz , 1h ), 3 . 54 ( m , 1h ), 3 . 29 ( dd , j = 5 . 6 , 2 . 4 hz , 1h ), 2 . 93 ( m , 1h ), 2 . 61 ( m , 1h ), 2 . 43 ( m , 1h ), 2 . 18 ( m , 1h ), 2 . 01 ( m , 1h ), 1 . 59 - 1 . 46 ( m , 2h ), 1 . 43 ( m , 1h ), 1 . 35 - 1 . 29 ( m , 2h ), 1 . 25 ( d , j = 7 . 0 hz , 3h ), 1 . 03 ( d , j = 7 . 2 hz , 3h ), 1 . 00 ( d , j = 7 . 0 hz , 3h ), 0 . 94 ( s , 9h ), 0 . 92 ( s , 9h ), 0 . 91 ( s , 9h ), 0 . 82 ( d , j = 7 . 0 hz , 3h ), 0 . 79 ( d , j = 6 . 7 hz , 3h ), 0 . 77 ( d , j = 6 . 5 hz , 3h ), 0 . 13 ( s , 3h ), 0 . 12 ( s , 3h ), 0 . 09 ( s , 3h ), 0 . 08 ( s , 3h ), 0 . 05 ( s , 3h ), 0 . 02 ( s , 3h ); δ 3 c nmr ( 75 mhz , cdcl 3 ) δ 200 . 7 , 159 . 8 , 153 . 3 , 144 . 3 , 134 . 0 , 133 . 3 , 131 . 1 , 130 . 8 , 128 . 6 , 127 . 7 , 127 . 2 , 126 . 8 , 126 . 5 , 125 . 7 , 113 . 4 , 100 . 8 , 86 . 7 , 82 . 7 , 80 . 4 , 72 . 8 , 66 . 5 , 65 . 8 , 65 . 2 , 55 . 2 , 47 . 0 , 42 . 8 , 42 . 1 , 39 . 1 , 35 . 6 , 34 . 9 , 34 . 0 , 32 . 3 , 26 . 1 , 26 . 0 , 25 . 9 , 19 . 7 , 18 . 39 , 18 . 36 , 18 . 1 , 16 . 4 , 15 . 2 , 14 . 7 , 12 . 4 , 10 . 7 , − 2 . 8 , − 3 . 6 , − 3 . 7 , − 4 . 0 , − 4 . 1 ; lrms ( esi ) 1209 . 7 [ m + na ]+, 577 . 4 , 359 . 2 , 243 . 1 , 165 . 0 ; hrms ( esi ) calcd for c 72 h 110 8 si 3 na 1209 . 7406 [ m + na ]+, found 1209 . 7466 ; [ α ] 21 d 8 . 6 ( c 2 . 5 , chcl 3 ). nicl 2 . 6h 2 o ( 0 . 20 g , 0 . 84 mmol ) then portion wise nabh 4 ( 0 . 17 g , 4 . 49 mmol ) were added to a stirred solution of unsaturated ketone 89 ( 2 . 60 g , 1 . 72 μmol ) in meoh ( 60 ml ), thf ( 20 ml ) at 0 ° c . after 1 h , the reaction mixture was evaporated and filtered with celite using et 2 o as an eluent ( 30 ml ). the organic phase was concentrated and the residue was purified by flash chromatography ( etoac / hexane 1 : 9 ) to yield 90 ( 1 . 55 g , 76 %) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2855 , 1713 , 1616 , 1518 , 1462 , 1251 , 1076 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 52 - 7 . 50 ( m , 6h ), 7 . 42 - 7 . 24 ( m , 1h ), 6 . 92 - 6 . 86 ( m , 2h ), 5 . 87 ( dd , j = 15 . 7 , 6 . 0 hz , 2h ), 5 . 60 ( dt , j = 15 . 8 , 5 . 9 hz , 1h ), 5 . 50 ( m , 1h ), 5 . 49 ( s , 1h ), 5 . 37 ( dd , j = 10 . 9 , 8 . 5 hz , 1h ), 4 . 59 ( m , 1h ), 4 . 17 ( dd , j = 11 . 3 , 4 . 7 hz , 1h ), 3 . 98 ( m , 2h ), 3 . 82 ( s , 3h ), 3 . 62 - 3 . 55 ( m , 3h ), 3 . 29 ( m , 1h ), 2 . 73 ( m , 1h ), 2 . 65 ( m , 1h ), 2 . 49 ( m , 2h ), 2 . 06 ( m , 1h ), 1 . 63 - 1 . 50 ( m , 2h ), 1 . 47 - 1 . 32 ( m , 2h ), 1 . 27 ( d , j = 7 . 1 hz , 3h ), 1 . 26 ( m , 1h ), 1 . 06 ( d , j = 7 . 3 hz , 3h ), 1 . 03 ( d , j = 7 . 2 hz , 3h ), 0 . 97 - 0 . 94 ( m , 27h ), 0 . 90 - 0 . 84 ( m , 2h ), 0 . 83 ( d , j = 6 . 7 hz , 3h ), 0 . 76 ( d , j = 7 . 0 hz , 3h ), 0 . 69 ( d , j = 5 . 7 hz , 3h ), 0 . 17 - 0 . 05 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 211 . 7 , 159 . 8 , 144 . 4 , 134 . 3 , 133 . 1 , 131 . 4 , 130 . 9 , 128 . 6 , 127 . 9 , 127 . 6 , 127 . 1 , 126 . 8 , 126 . 4 , 113 . 4 , 100 . 8 , 86 . 7 , 82 . 9 , 81 . 0 , 72 . 8 , 66 . 5 , 65 . 2 , 55 . 2 , 48 . 3 , 43 . 0 , 42 . 2 , 39 . 8 , 38 . 3 , 35 . 2 , 35 . 1 , 31 . 9 , 31 . 3 , 29 . 7 , 26 . 2 , 26 . 0 , 25 . 9 , 19 . 6 , 18 . 6 , 18 . 4 , 18 . 1 , 16 . 3 , 14 . 6 , 12 . 1 , 9 . 7 , − 2 . 9 , − 3 . 5 , − 3 . 6 , − 4 . 0 , − 4 . 1 , − 4 . 2 ; lrms ( esi ) 1211 . 8 [ m + na ]+, 577 . 3 , 463 . 3 , 413 . 3 , 359 . 2 , 316 . 9 , 284 . 3 ; hrms ( esi ) calcd for c 72 h 112 o 8 si 3 na 1211 . 7563 [ m + na ]+, found 1211 . 7629 ; [ α ] 20 d − 4 . 3 ( c 1 . 0 , chcl 3 ). ( 2s , 3r , 6s , 8r , 9r , 10s , 11z , 13s , 15s , 16s , 17e )- 9 , 13 , 15 - tris ( tert - butyldimethylsilyloxy )- 2 -(( 4s , 5s )- 2 -( 4 - methoxyphenyl )- 5 - methyl - 1 , 3 - dioxan - 4 - yl )- 6 , 8 , 10 , 16 - tetramethyl - 19 -( trityloxy ) nonadeca - 11 , 17 - dien - 3 - ol ( 91 ). nabh 4 ( 0 . 074 g , 1 . 96 mmol ) was added to a solution of ketone 90 ( 1 . 55 g , 1 . 30 mmol ) in meoh ( 21 ml ) at 0 ° c . after stirring for 2 h at 0 ° c ., the reaction mixture was evaporated and water ( 30 ml ) was added . the reaction mixture was extracted with ether ( 2 × 40 ml ) and washed with brine ( 50 ml ), dried over mgso 4 and concentrated in vacuo . the residue was purified by flash chromatography ( etoac / hexane 1 : 9 ) to yield 1 . 02 g of major product β ( less polar , 62 %) and 0 . 60 g ( more polar , 36 %) of minor product α as colorless oils : ( 91β ) ir ( chcl 3 ) 3540 , 2956 , 2929 , 2855 , 1615 , 1518 , 1461 , 1385 , 1252 , 1074 , 835 , 773 , 706 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 54 - 7 . 50 ( m , 6h ), 7 . 42 ( m , 2h ), 7 . 37 - 7 . 25 ( m , 9h ), 6 . 94 - 6 . 91 ( m , 2h ), 5 . 88 ( dd , j = 15 . 7 , 6 . 0 hz , 1h ), 5 . 61 ( dt , j = 16 . 0 , 5 . 7 hz , 1h ), 5 . 56 ( s , 1h ), 5 . 50 ( m , 1h ), 5 . 37 ( dd , j = 10 . 8 , 8 . 6 hz , 1h ), 4 . 60 ( m , 1h ), 4 . 17 ( dd , j = 11 . 2 , 4 . 6 hz , 1h ), 3 . 96 ( m , 1h ), 3 . 87 ( m , 1h ), 3 . 84 ( s , 3h ), 3 . 74 ( m , 1h ), 3 . 64 - 3 . 53 ( m , 3h ), 3 . 32 ( m , 1h ), 3 . 20 ( br , 1h ), 2 . 67 ( m , 1h ), 2 . 44 ( m , 1h ), 2 . 18 ( m , 1h ), 1 . 83 ( m , 1h ), 1 . 67 - 1 . 51 ( m , 2h ), 1 . 50 - 1 . 32 ( m , 3h ), 1 . 26 ( m , 1h ), 1 . 08 ( d , j = 6 . 8 hz , 3h ), 1 . 07 ( m , 2h ), 1 . 06 ( d , j = 7 . 0 hz , 3h ), 1 . 04 ( d , j = 7 . 4 hz , 3h ), 0 . 98 - 0 . 85 ( m , 2h ), 0 . 82 ( d , j = 6 . 7 hz , 3h ), 0 . 81 ( d , j = 6 . 7 hz , 3h ), 0 . 77 ( d , j = 6 . 0 hz , 3h ), 0 . 18 - 0 . 09 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 160 . 0 , 144 . 5 , 144 . 4 , 134 . 4 , 132 . 9 , 131 . 6 , 130 . 7 , 128 . 6 , 127 . 6 , 127 . 2 , 126 . 8 , 126 . 7 , 126 . 4 , 113 . 6 , 101 . 2 , 89 . 1 , 86 . 7 , 81 . 1 , 76 . 8 , 73 . 1 , 72 . 8 , 66 . 5 , 55 . 2 , 43 . 0 , 42 . 3 , 39 . 9 , 37 . 2 , 35 . 3 , 35 . 1 , 34 . 7 , 32 . 3 , 30 . 4 , 30 . 2 , 26 . 2 , 26 . 1 , 25 . 9 , 19 . 6 , 18 . 8 , 18 . 4 , 18 . 13 , 18 . 10 , 16 . 3 , 14 . 6 , 11 . 9 , 5 . 5 , − 2 . 8 , − 3 . 56 , − 3 . 61 , − 4 . 0 , − 4 . 1 , − 4 . 16 , − 4 . 25 ; lrms ( api - es ) 1213 . 6 [ m + na ]+, 557 . 0 , 359 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 72 h 114 o 8 si 3 na 1213 . 7719 [ m + na ]+, found 1213 . 7717 ; [ α ] 20 d − 0 . 68 ( c 7 . 1 , chcl 3 ): ( 91α ) ir ( chcl 3 ) 3531 , 2956 , 2929 , 2855 , 1615 , 1518 , 1462 , 1383 , 1252 , 1075 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 53 - 7 . 49 ( m , 6h ), 7 . 44 - 7 . 41 ( m , 2h ), 7 . 36 - 7 . 24 ( m , 9h ), 6 . 94 - 6 . 91 ( m , 2h ), 5 . 86 ( dd , j = 15 . 7 , 6 . 0 hz , 1h ), 5 . 60 ( dt , j = 15 . 7 , 5 . 7 hz , 1h ), 5 . 54 ( s , 1h ), 5 . 56 - 5 . 47 ( m , 1h ), 5 . 36 ( dd , j = 11 . 0 , 8 . 6 hz , 1h ), 4 . 60 ( m , 1h ), 4 . 17 ( dd , j = 11 . 2 , 4 . 6 hz , 1h ), 3 . 97 - 3 . 91 ( m , 2h ), 3 . 84 ( s , 3h ), 3 . 62 ( d , j = 4 . 9 hz , 2h ), 3 . 61 - 3 . 53 ( m , 2h ), 3 . 32 ( m , 1h ), 2 . 67 ( m , 1h ), 2 . 44 ( m , 1h ), 2 . 16 ( m , 1h ), 1 . 82 ( m , 1h ), 1 . 72 - 1 . 50 ( m , 4h ), 1 . 42 - 1 . 33 ( m , 2h ), 1 . 32 - 1 . 22 ( m , 2h ), 1 . 14 ( d , j = 7 . 1 hz , 3h ), 1 . 06 (( d , j = 7 . 0 hz , 3h ), 1 . 03 ( d , j = 7 . 0 hz , 3h ), 0 . 97 - 0 . 92 ( m , 27h ), 0 . 90 - 0 . 85 ( m , 2h ), 0 . 81 ( d , j = 6 . 4 hz , 3h ), 0 . 79 ( d , j = 6 . 6 hz , 3h ), 0 . 76 ( d , j = 5 . 7 hz , 3h ), 0 . 17 - 0 . 09 ( m , 18h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 160 . 0 , 144 . 6 , 144 . 4 , 134 . 4 , 133 . 0 , 131 . 6 , 131 . 1 , 128 . 7 , 127 . 7 , 127 . 6 , 127 . 3 , 126 . 8 , 126 . 7 , 126 . 4 , 113 . 6 , 101 . 0 , 86 . 7 , 82 . 8 , 81 . 2 , 75 . 1 , 73 . 3 , 72 . 8 , 66 . 6 , 65 . 2 , 55 . 2 , 43 . 0 , 42 . 3 , 39 . 9 , 37 . 9 , 35 . 3 , 35 . 1 , 34 . 6 , 33 . 4 , 30 . 3 , 26 . 3 , 26 . 1 , 26 . 0 , 19 . 7 , 19 . 0 , 18 . 4 , 18 . 1 , 16 . 4 , 14 . 6 , 11 . 9 , 11 . 1 , − 2 . 8 , − 3 . 5 , − 4 . 0 , − 4 . 07 , − 4 . 13 ; lrms ( esi ) 1213 . 8 [ m + na ]+, 633 . 2 , 359 . 2 ; hrms ( esi ) calcd for c 72 h 114 o 8 si 3 na 1213 . 7719 [ m + na ]+, found 1213 . 7766 ; [ α ] 20 d − 1 . 4 ( c 4 . 7 , chcl 3 ). tbsotf ( 0 . 30 ml , 2 . 57 mmol ) was added to a stirred solution of alcohol 91β ( 1 . 02 g , 0 . 86 mmol ) and 2 , 6 - lutidine ( 0 . 20 ml , 1 . 71 mmol ) in ch 2 cl 2 ( 17 ml ) at 0 ° c . and the reaction mixture was stirred for 1 h at ambient temperature . the reaction mixture was quenched by the addition of water ( 50 ml ). the reaction mixture was extracted by ch 2 cl 2 and dried over mgso 4 followed by the evaporation of the solution under reduced pressure . the residue was purified by short column chromatography ( hexane / etoac 9 : 1 ) to yield product ( 0 . 97 g , 86 %) as a colorless oil : ir ( chcl 3 ) 2955 , 2928 , 2856 , 1615 , 1518 , 1471 , 1462 , 1387 , 1251 , 1074 , 1038 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 52 - 7 . 46 ( m , 6h ), 7 . 45 - 7 . 42 ( m , 2h ), 7 . 35 - 7 . 22 ( m , 9h ), 6 . 92 - 6 . 89 ( m , 2h ), 5 . 86 ( dd , j = 15 . 7 , 6 . 0 hz , 1h ), 5 . 59 ( dt , j = 15 . 7 , 4 . 9 hz , 1h ), 5 . 48 ( m , 1h ), 5 . 47 ( s , 1h ), 5 . 36 ( dd , j = 11 . 1 , 8 . 6 hz , 1h ), 4 . 58 ( m , 1h ), 4 . 15 ( dd , j = 11 . 2 , 4 . 6 hz , 1h ), 3 . 96 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 73 - 3 . 66 ( m , 2h ), 3 . 60 ( d , j = 5 . 6 hz , 2h ), 3 . 55 ( m , 1h ), 3 . 19 ( m , 1h ), 2 . 65 ( m 1h ), 2 . 42 ( m , 1h ), 2 . 07 ( m , 1h ), 1 . 91 ( m , 1h ), 1 . 57 ( m , 2h ), 1 . 40 - 1 . 21 ( m , 3h ), 1 . 14 ( m , 1h ), 1 . 06 ( d , j = 6 . 7 hz , 3h ), 1 . 04 ( d , j = 5 . 9 hz , 3h ), 1 . 02 ( d , j = 6 . 9 hz , 3h ), 0 . 96 - 0 . 92 ( m , 36h ), 0 . 88 - 0 . 84 ( m , 3h ), 0 . 80 ( m , 1h ), 0 . 77 ( d , j = 6 . 5 hz , 3h ), 0 . 76 ( d , j = 6 . 4 hz , 3h ), 0 . 71 ( d , j = 5 . 1 hz , 3h ), 0 . 16 - 0 . 03 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 7 , 144 . 6 , 144 . 4 , 134 . 4 , 133 . 2 , 131 . 7 , 131 . 4 , 128 . 7 , 127 . 7 , 127 . 2 , 126 . 8 , 126 . 4 , 113 . 4 , 100 . 4 , 86 . 7 , 81 . 8 , 81 . 4 , 75 . 0 , 73 . 3 , 72 . 8 , 66 . 5 , 65 . 2 , 55 . 2 , 43 . 1 , 42 . 3 , 39 . 7 , 38 . 9 , 35 . 3 , 35 . 0 , 34 . 0 , 31 . 2 , 30 . 7 , 30 . 6 , 26 . 2 , 26 . 1 , 26 . 00 , 25 . 95 , 19 . 5 , 19 . 1 , 18 . 4 , 18 . 13 , 18 . 10 , 16 . 5 , 14 . 5 , 12 . 4 , 10 . 6 , − 2 . 8 , − 3 . 4 , − 3 . 95 , − 3 . 98 , − 4 . 2 , − 4 . 3 ; lrms ( esi ) 1327 . 8 [ m + na ]+, 977 . 8 , 739 . 6 ; hrms ( esi ) calcd for c 78 h 128 o 8 si 4 na 1327 . 8584 [ m + na ]+, found 1327 . 8534 ; [ α ] 20 d + 6 . 7 ( c 0 . 65 , chcl 3 ). dibal ( 1 . 0 m in hexane , 7 . 4 ml , 7 . 4 mmol ) was added to a stirred solution of tbs protected acetal 92 ( 0 . 97 g , 0 . 74 mmol ) in anhydrous ch 2 cl 2 ( 3 ml ), under an atmosphere of n 2 at 0 ° c . dropwise . after stirring for additional 30 min at 0 ° c ., the reaction mixture was quenched by the careful addition of aqueous sat &# 39 ; d potassium sodium tartrate solution ( 30 ml ) and stirred for 3 h at room temperature . the organic layer was separated , and the aqueous layer was extracted with ch 2 cl 2 ( 20 ml ). the combined organic layers were washed with brine and dried over mgso 4 followed by the evaporation of the organic solution under reduced pressure . the residue was purified by column chromatography ( etoac / hexane 1 : 9 ) to obtain 93 ( 0 . 94 g , 97 %) as a colorless oil : ir ( chcl 3 ) 3501 , 2956 , 2929 , 2856 , 1613 , 1514 , 1471 , 1462 , 1251 , 1075 , 835 , 773 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 55 - 7 . 51 ( m , 6h ), 7 . 37 - 7 . 25 ( m , 11h ), 6 . 94 - 6 . 92 ( m , 2h ), 5 . 90 ( dd , j = 15 . 7 , 5 . 9 hz , 1h ), 5 . 62 ( dt , j = 15 . 6 , 5 . 6 hz , 1h ), 5 . 56 - 5 . 48 ( m , 1h ), 5 . 40 ( dd , j = 11 . 2 , 8 . 5 hz , 1h ), 4 . 61 ( m , 1h ), 4 . 60 ( s , 2h ), 3 . 99 ( m , 1h ), 3 . 90 ( m , 1h ), 3 . 83 ( s , 3h ), 3 . 69 ( m , 1h ), 3 . 64 ( d , j = 5 . 3 hz , 1h ), 3 . 53 ( m , 1h ), 3 . 31 ( m , 1h ), 2 . 99 ( m 1h ), 2 . 70 ( m , 1h ), 2 . 47 ( m , 1h ), 2 . 00 ( m , 2h ), 1 . 65 - 1 . 52 ( m , 3h ), 1 . 45 - 1 . 37 ( m , 1h ), 1 . 33 ( m , 1h ), 1 . 30 ( m , 1h ), 1 . 20 ( d , j = 6 . 9 hz , 3h ), 1 . 10 ( d , j = 6 . 6 hz , 3h ), 1 . 09 ( d , j = 6 . 9 hz , 3h ), 1 . 05 ( d , j = 7 . 0 hz , 3h ), 1 . 00 - 0 . 96 ( m , 36h ), 0 . 92 - 0 . 86 ( m , 2h ), 0 . 82 ( d , j = 6 . 6 hz , 3h ), 0 . 76 ( d , j = 5 . 5 hz , 3h ), 0 . 19 - 0 . 11 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 144 . 5 , 144 . 4 , 134 . 3 , 133 . 1 , 131 . 5 , 130 . 5 , 129 . 2 , 128 . 6 , 127 . 6 , 126 . 8 , 126 . 4 , 113 . 8 , 86 . 7 , 86 . 0 , 81 . 1 , 75 . 3 , 73 . 6 , 72 . 8 , 66 . 5 , 65 . 1 , 65 . 0 , 55 . 1 , 43 . 0 , 42 . 3 , 40 . 5 , 40 . 0 , 36 . 8 , 35 . 2 , 35 . 1 , 34 . 0 , 32 . 1 , 30 . 4 , 26 . 2 , 26 . 1 , 26 . 0 , 25 . 9 , 19 . 6 , 18 . 9 , 18 . 4 , 18 . 1 , 16 . 5 , 15 . 8 , 14 . 6 , 9 . 9 , − 2 . 8 , − 3 . 4 , − 3 . 5 , − 3 . 8 , − 4 . 0 , − 4 . 2 , − 4 . 4 ; lrms ( esi ) 1329 . 8 [ m + na ]+, 1087 . 7 , 801 . 5 , 669 . 4 , 537 . 3 , 480 . 2 , 359 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 78 h 130 o 8 si 4 na 1329 . 8741 [ m + na ]+, found 1329 . 8778 ; [ α ] 20 d − 9 . 9 ( c 0 . 36 , chcl 3 ). the alcohol 93 ( 0 . 94 g , 0 . 72 μmol ) in ch 2 cl 2 ( 20 ml ) was treated with dess - martin periodinane ( 0 . 46 g , 1 . 08 μmol ). after 1 h , the mixture was quenched with saturated nahco 3 ( 20 ml ) and na 2 s 2 o 3 ( 20 ml ). the aqueous layer was extracted with ethyl ether ( 20 ml × 2 ) and the combined extracts were dried over anhydrous mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 9 : 1 ) to remove dess - martin residue provided crude aldehyde as a colorless oil , which was used for the next reaction without further purification . to a stirred solution of the above crude aldehyde and 1 - bromoallyl trimethylsilane ( 0 . 89 g ) in anhydrous thf ( 18 ml ) under an atmosphere of n 2 at room temperature was added crcl 2 ( 0 . 73 g , 5 . 94 mmol ), and the mixture was stirred for additional 14 h at ambient temperature . the reaction mixture was diluted with hexane followed by filtration through celite . after the evaporation of the solvent under reduced pressure , the residue was purified by short silica gel column chromatography using etoac / hexane ( 1 : 9 ) as an eluent . the foregoing product in thf ( 40 ml ) was cooled to 0 ° c . and nah ( 95 % w / w , 0 . 36 g , 14 . 4 mmol ) was added in one portion . the ice bath was removed after 15 min and the mixture was stirred for 2 h at ambient temperature . the reaction mixture was cooled to 0 ° c ., quenched with h 2 o ( 5 ml ), extracted with ethyl ether ( 20 ml × 2 ). the combined organic layers were washed with brine and dried over mgso 4 followed by the evaporation of the organic solution under reduced pressure . the residue was purified by column chromatography ( hexane / etoac 98 : 2 ) to obtain 94 ( 0 . 81 g , 85 % for 3 steps ) as a colorless oil : ir ( chcl 3 ) 2955 , 2928 , 2856 , 1614 , 1514 , 1471 , 1462 , 1249 , 1076 , 835 , 772 , 705 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 60 - 7 . 56 ( m , 6h ), 7 . 43 - 7 . 27 ( m , 1h ), 6 . 99 - 6 . 96 ( m , 1h ), 6 . 71 ( ddd , j = 16 . 9 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 14 ( t , j = 11 . 0 hz , 1h ), 5 . 97 ( dd , j = 15 . 7 , 5 . 9 hz , 1h ), 5 . 82 - 5 . 77 ( m , 1h ), 5 . 74 - 5 . 70 ( m , 1h ), 5 . 68 - 5 . 62 ( m , 1h ), 5 . 61 - 5 . 56 ( m , 1h ), 5 . 46 ( dd , j = 11 . 1 , 8 . 6 hz , 1h ), 5 . 28 ( d , j = 16 . 9 hz , 1h ), 5 . 20 ( d , j = 10 . 3 hz , 1h ), 4 . 66 ( m , 3h ), 4 . 05 ( m , 1h ), 3 . 86 ( s , 3h ), 3 . 76 ( m , 1h ), 3 . 69 ( d , j = 5 . 2 hz , 1h ), 3 . 48 ( m , 1h ), 3 . 35 ( m , 1h ), 3 . 15 ( m , 1h ), 2 . 76 ( m , 1h ), 2 . 53 ( m , 1h ), 2 . 34 ( m , 1h ), 1 . 82 ( m , 1h ), 1 . 70 - 1 . 57 ( m , 3h ), 1 . 56 - 1 . 32 ( m , 3h ), 1 . 25 ( d , j = 6 . 8 hz , 3h ), 1 . 14 ( d , j = 7 . 1 hz , 3h ), 1 . 12 ( m , 2h ), 1 . 11 ( d , j = 7 . 1 hz , 3h ), 1 . 08 - 1 . 03 ( m , 36h ), 0 . 98 - 0 . 90 ( m , 2h ), 0 . 86 ( d , j = 6 . 6 hz , 3h ), 0 . 76 ( d , j = 5 . 1 hz , 3h ), 0 . 25 - 0 . 13 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 146 . 2 , 144 . 6 , 144 . 4 , 134 . 5 , 134 . 3 , 133 . 2 , 132 . 4 , 131 . 4 , 130 . 2 , 129 . 0 , 128 . 7 , 127 . 7 , 126 . 8 , 126 . 5 , 117 . 2 , 113 . 7 , 86 . 7 , 84 . 5 , 81 . 3 , 75 . 1 , 72 . 9 , 66 . 6 , 65 . 2 , 55 . 1 , 43 . 0 , 42 . 3 , 40 . 6 , 40 . 2 , 35 . 6 , 35 . 25 , 35 . 19 , 33 . 9 , 32 . 6 , 30 . 3 , 26 . 3 , 26 . 1 , 26 . 04 , 25 . 99 , 19 . 6 , 18 . 9 , 18 . 4 , 18 . 2 , 16 . 6 , 14 . 7 , 9 . 2 , − 2 . 8 , − 3 . 36 , − 3 . 4 , − 3 . 5 , − 3 . 9 , − 4 . 1 , − 4 . 4 ; lrms ( esi ) 1351 . 8 [ m + na ]+, 837 . 1 , 763 . 1 , 689 . 541 . 0 ; hrms ( esi ) calcd for c 81 h 132 o 7 si 4 na 1351 . 8948 [ m + na ]+, found 1351 . 8973 ; [ α ] 20 d + 0 . 4 ( c 0 . 51 , chcl 3 ). znbr 2 solution ( 0 . 42 g in 5 ml ch 2 cl 2 and 0 . 8 ml of meoh ) was added to a stirred solution of trityl ether 94 ( 0 . 50 g , 0 . 38 μmol ) in meoh ( 3 ml ), ch 2 cl 2 ( 18 ml ) at 0 ° c . dropwise for 30 min . after 4 h , the reaction mixture was quenched with saturated nahco 3 solution ( 20 ml ) and extracted with et 2 o ( 10 ml × 2 ). the organic phase was separated , dried with mgso 4 and concentrated . the residue was purified by flash chromatography ( etoac / hexane 1 : 9 ) to yield 0 . 34 g of product 95 ( 83 %) as a colorless oil : ir ( chcl 3 ) 3410 , 2956 , 2929 , 2856 , 1613 , 1514 , 1471 , 1251 , 1076 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 31 - 7 . 29 ( m , 2h ), 6 . 90 - 6 . 87 ( m , 2h ), 6 . 60 ( ddd , j = 16 . 8 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 02 ( t , j = 11 . 0 hz , 1h ), 5 . 79 ( dd , j = 15 . 6 , 5 . 8 hz , 1h ), 5 . 62 ( d , j = 9 . 3 hz , 1h ), 5 . 60 ( m , 1h ), 5 . 47 ( t , j = 10 . 3 hz , 1h ), 5 . 32 ( dd , j = 10 . 7 , 8 . 9 hz , 1h ), 5 . 18 ( d , j = 16 . 8 hz , 1h ), 5 . 10 ( d , j = 10 . 2 hz , 1h ), 4 . 54 ( m , 3h ), 4 . 07 ( d , j = 5 . 9 hz , 2h ), 3 . 89 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 64 ( m , 1h ), 3 . 35 ( m , 1h ), 3 . 24 ( br , 1h ), 3 . 00 ( m , 1h ), 2 . 61 ( m , 1h ), 2 . 40 ( m , 1h ), 1 . 68 ( m , 1h ), 1 . 55 - 1 . 42 ( m , 3h ), 1 . 38 - 1 . 21 ( m , 3h ), 1 . 12 ( d , j = 6 . 7 hz , 3h ), 1 . 02 - 0 . 99 ( m , 3h ), 0 . 98 ( d , j = 7 . 0 hz , 3h ), 0 . 94 - 0 . 89 ( m , 40h ), 0 . 79 ( d , j = 6 . 9 hz , 3h ), 0 . 76 ( d , j = 6 . 3 hz , 3h ), 0 . 11 - 0 . 06 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 134 . 9 , 134 . 5 , 133 . 1 , 132 . 4 , 131 . 5 , 131 . 4 , 129 . 1 , 128 . 9 , 128 . 7 , 117 . 2 , 113 . 7 , 84 . 5 , 81 . 3 , 75 . 1 , 72 . 7 , 66 . 4 , 64 . 1 , 55 . 3 , 42 . 7 , 42 . 0 , 40 . 5 , 40 . 4 , 35 . 5 , 35 . 23 , 35 . 20 , 33 . 9 , 32 . 6 , 30 . 5 , 26 . 3 , 26 . 03 , 26 . 00 , 25 . 96 , 19 . 7 , 18 . 9 , 18 . 8 , 18 . 5 , 18 . 2 , 18 . 1 , 16 . 6 , 14 . 7 , 9 . 2 , − 2 . 8 , − 3 . 47 , − 3 . 53 , − 4 . 03 , − 4 . 05 , − 4 . 2 , − 4 . 5 , − 4 . 7 ; lrms ( esi ) 1109 . 7 [ m + na ]+, 945 . 3 , 797 . 3 , 723 . 2 , 577 . 4 , 499 . 2 , 413 . 3 , 359 . 3 ; hrms ( esi ) calcd for c 62 h 180 o 7 si 4 na 1109 . 7852 [ m + na ]+, found 1109 . 7898 ; [ α ] 20 d − 2 . 0 ( c 2 . 6 , chcl 3 ). the alcohol 95 ( 0 . 34 g , 0 . 31 μmol ) in ch 2 cl 2 ( 20 ml ) was treated with dess - martin periodinane ( 0 . 20 g , 0 . 47 μmol ). after 1 h , the mixture was quenched with saturated nahco 3 ( 5 ml ) and na 2 s 2 o 3 ( 5 ml ). the aqueous layer was extracted with ethyl ether ( 10 ml × 2 ) and the combined extracts were dried over anhydrous mgso 4 . filtration and concentration followed by short flash column chromatography ( hexane / etoac 9 : 1 ) to remove the dess - martin residue provided the crude aldehyde as a colorless oil , which was used for the next reaction without further purification . to a stirred solution of bis ( 2 , 2 , 2 - trifluoroethyl )-( methoxycarbonylmethyl ) phosphate ( 0 . 080 ml , 0 . 37 μmol ), 18 - crown - 6 ( 0 . 41 g , 1 . 55 mmol ) in thf ( 6 ml ) cooled to − 78 ° c . was added dropwise potassium bis ( trimethylsilyl ) amide ( 0 . 75 ml , 0 . 37 μmol , 0 . 5m solution in toluene ). thereafter the above aldehyde in thf ( 1 ml ) was added and the solution was stirred for 4 h at − 78 ° c . the reaction mixture was quenched by addition of a sat &# 39 ; d nh 4 cl solution ( 5 ml ) and diluted with diethyl ether ( 20 ml ). the layers were separated and organic phase was washed with brine ( 30 ml ) and dried with mgso 4 , filtered , and concentrated . the residue was purified by flash chromatography ( etoac / hexane 5 : 95 ) to obtain ( e , z )- doubly unsaturated ester 96 ( 0 . 32 g , 90 % for 2 steps ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2885 , 1722 , 1641 , 1514 , 1471 , 1250 , 1174 , 1075 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 34 ( dd , j = 15 . 5 , 11 . 2 hz , 1h ), 7 . 29 - 7 . 26 ( m , 2h ), 6 . 87 - 6 . 84 ( m , 2h ), 6 . 56 ( ddd , j = 17 . 0 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 52 ( t , j = 11 . 4 hz , 1h ), 6 . 19 ( dd , j = 15 . 5 , 6 . 4 hz , 1h ), 5 . 99 ( t , j = 11 . 0 hz , 1h ), 5 . 57 ( t , j = 10 . 5 hz , 1h ), 5 . 54 ( d , j = 11 . 3 hz , 1h ), 5 . 42 ( m , 1h ), 5 . 30 ( m , 1h ), 5 . 15 ( d , j = 16 . 8 hz , 1h ), 5 . 07 ( d , j = 10 . 1 hz , 1h ), 4 . 51 ( m , 3h ), 3 . 92 ( m , 1h ), 3 . 78 ( s , 3h ), 3 . 70 ( s , 3h ), 3 . 61 ( m , 1h ), 3 . 32 ( dd , j = 7 . 9 , 2 . 8 hz , 1h ), 3 . 20 ( m , 1h ), 2 . 97 ( m , 2h ), 2 . 57 ( m , 2h ), 1 . 65 ( m , 1h ), 1 . 56 - 1 . 39 ( m , 3h ), 1 . 29 - 1 . 16 ( m , 3h ), 1 . 10 ( d , j = 6 . 8 hz , 3h ), 1 . 03 ( d , j = 6 . 9 hz , 3h ), 0 . 98 ( d , j = 7 . 0 hz , 3h ), 0 . 94 ( d , j = 6 . 9 hz , 3h ), 0 . 93 - 0 . 83 ( m , 39h ), 0 . 77 ( m , 1h ), 0 . 91 ( s , 9h ), 0 . 87 ( s , 9h ), 0 . 83 ( d , j = 6 . 4 hz , 3h ), 0 . 82 ( d , j = 6 . 0 hz , 3h ), 0 . 13 ( s , 3h ), 0 . 76 ( d , j = 6 . 6 hz , 3h ), 0 . 71 ( d , j = 5 . 9 hz , 3h ), 0 . 10 - 0 . 02 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 159 . 0 , 147 . 2 , 145 . 6 , 134 . 5 , 133 . 1 , 132 . 4 , 131 . 5 , 131 . 4 , 129 . 0 , 128 . 9 , 126 . 4 , 117 . 1 , 115 . 1 , 113 . 7 , 84 . 4 , 81 . 3 , 75 . 0 , 72 . 8 , 72 . 7 , 66 . 4 , 55 . 2 , 50 . 9 , 42 . 9 , 42 . 6 , 40 . 5 , 40 . 2 , 35 . 3 , 35 . 2 , 33 . 8 , 32 . 6 , 30 . 5 , 26 . 3 , 26 . 0 , 25 . 9 , 19 . 6 , 18 . 9 , 18 . 8 , 18 . 4 , 18 . 2 , 18 . 1 , 16 . 7 , 14 . 5 , 9 . 2 , − 2 . 8 , − 3 . 4 , − 3 . 5 , − 3 . 6 , − 4 . 07 , − 4 . 14 , − 4 . 24 , − 4 . 49 ; lrms ( esi ) 1163 . 8 [ m + na ]+, 1107 . 9 , 782 . 5 ; hrms ( esi ) calcd for c 65 h 120 o 8 si 4 na 1163 . 7958 [ m + na ]+, found 1163 . 8004 ; [ α ] 20 d − 27 . 3 ( c 5 . 0 , chcl 3 ). the ester 96 ( 0 . 15 g , 0 . 14 μmol ) was added to ch 2 cl 2 ( 5 ml ) and h 2 o ( 0 . 2 ml ) and ddq ( 34 mg , 0 . 15 μmol ) was added at 0 ° c . after 1 h of stirring at 0 ° c ., the reaction mixture was quenched by adding sat &# 39 ; d nahco 3 ( 5 ml ). the organic phase was washed by sat &# 39 ; d nahco 3 solution ( 3 × 10 ml ) and brine , dried over mgso 4 and concentrated . purification by flash column chromatography ( etoac / hexane 1 : 9 ) furnished 97 ( 0 . 12 g , 90 %) as a colorless oil : ir ( chcl 3 ) 3540 , 2956 , 2929 , 2856 , 1641 , 1601 , 1471 , 1462 , 1407 , 1379 , 1361 , 1255 , 1174 , 1089 , 1004 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 33 ( dd , j = 15 . 5 , 11 . 2 hz , 1h ), 6 . 61 ( ddd , j = 16 . 9 , 10 . 5 , 10 . 4 hz , 1h ), 6 . 51 ( t , j = 11 . 4 hz , 1h ), 6 . 17 ( dd , j = 15 . 5 , 5 . 9 hz , 1h ), 6 . 07 ( t , j = 11 . 0 hz , 1h ), 5 . 54 ( d , j = 11 . 3 hz , 1h ), 5 . 45 - 5 . 37 ( m , 2h ), 5 . 28 ( m , 1h ), 5 . 18 ( d , j = 16 . 8 hz , 1h ), 5 . 09 ( d , j = 10 . 1 hz , 1h ), 4 . 51 ( m , 1h ), 3 . 91 ( m , 1h ), 3 . 74 ( m , 1h ), 3 . 69 ( s , 3h ), 3 . 45 ( m , 1h ), 3 . 23 ( m , 1h ), 3 . 76 ( m , 1h ), 2 . 56 ( m , 2h ), 2 . 29 ( br , 1h ), 1 . 68 ( m , 1h ), 1 . 56 - 1 . 41 ( m , 3h ), 1 . 34 - 1 . 17 ( m , 3h ), 1 . 02 ( d , j = 6 . 9 hz , 3h ), 0 . 97 ( d , j = 6 . 9 hz , 3h ), 0 . 94 ( d , j = 6 . 8 hz , 3h ), 0 . 90 - 0 . 84 ( m , 40h ), 0 . 81 ( d , j = 5 . 8 hz , 3h ), 0 . 77 ( d , j = 6 . 5 hz , 3h ), 0 . 76 ( d , j = 6 . 2 hz , 3h ), 0 . 08 - 0 . 01 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 147 . 3 , 145 . 5 , 135 . 3 , 133 . 0 , 132 . 3 , 131 . 5 , 129 . 9 , 126 . 4 , 117 . 6 , 115 . 2 , 81 . 3 , 77 . 5 , 76 . 7 , 72 . 7 , 66 . 4 , 50 . 9 , 42 . 9 , 42 . 6 , 40 . 1 , 37 . 9 , 36 . 1 , 35 . 4 , 35 . 2 , 33 . 8 ,. 32 . 2 , 30 . 6 , 26 . 2 , 26 . 0 , 25 . 9 , 19 . 6 , 19 . 0 , 18 . 4 , 18 . 10 , 18 . 05 , 17 . 7 , 16 . 6 , 14 . 4 , 6 . 9 , − 2 . 8 , − 3 . 5 , − 3 . 6 , − 3 . 7 , − 4 . 1 , − 4 . 15 , − 4 . 21 , − 4 . 4 ; lrms ( esi ) 1043 . 7 [ m + na ]+, 889 . 8 , 757 . 6 , 625 . 5 , 544 . 3 , 364 . 4 ; hrms ( esi ) calcd for c 57 h 112 o 7 si 4 na 1043 . 7383 [ m + na ]+, found 1043 . 7433 ; [ α ] 20 d − 40 . 3 ( c 2 . 1 , chcl 3 ). 1n aqueous koh solution ( 1 . 2 ml ) was added to a stirred solution of the above 97 ( 0 . 12 g , 0 . 12 μmol ) in etoh ( 12 ml ), thf ( 1 ml ) and the mixture was refluxed gently until the ester disappeared ( about 5 h ) as determined by tlc analysis . the ethanolic solution was concentrated and then diluted with ether ( 4 ml ). after the solution was acidified to ph3 with 1n hcl solution , organic phase was separated and aqueous phase was extracted with et 2 o ( 2 × 5 ml ). the combined organic phases were dried with mgso 4 , concentrated and used without further purification : ir ( chcl 3 ) 2957 , 2929 , 2857 , 1692 , 1471 , 1462 , 1254 , 1089 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 34 ( dd , j = 15 . 1 , 11 . 4 hz , 1h ), 6 . 64 ( ddd , j = 16 . 0 , 10 . 8 , 10 . 5 hz , 1h ), 6 . 61 ( t , j = 11 . 2 hz , 1h ), 6 . 22 ( dd , j = 15 . 4 , 6 . 0 hz , 1h ), 6 . 09 ( t , j = 11 . 0 hz , 1h ), 5 . 58 ( d , j = 11 . 3 hz , 1h ), 5 . 49 - 5 . 39 ( m , 2h ), 5 . 34 - 5 . 28 ( m , 1h ), 5 . 20 ( d , j = 16 . 7 hz , 1h ), 5 . 11 ( d , j = 10 . 2 hz , 1h ), 4 . 55 ( m , 1h ), 3 . 95 ( m , 1h ), 3 . 76 ( m , 1h ), 3 . 50 ( m , 1h ), 3 . 27 ( m , 1h ), 2 . 81 ( m , 1h ), 2 . 58 ( m , 2h ), 1 . 71 ( m , 1h ), 1 . 57 - 1 . 50 ( m , 3h ), 1 . 44 - 1 . 31 ( m , 3h ), 1 . 25 ( d , j = 7 . 3 hz , 3h ), 1 . 21 ( d , j = 6 . 1 hz , 3h ), 1 . 04 ( d , j = 6 . 9 hz , 3h ), 0 . 99 ( d , j = 7 . 0 hz , 3h ), 0 . 96 - 0 . 89 ( m , 40h ), 0 . 81 ( d , j = 6 . 2 hz , 3h ), 0 . 79 ( d , j = 5 . 9 hz , 3h ), 0 . 11 - 0 . 05 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 171 . 1 , 148 . 1 , 147 . 3 , 135 . 2 , 132 . 8 , 132 . 3 , 131 . 6 , 129 . 9 , 126 . 6 , 117 . 6 , 115 . 0 , 81 . 3 , 77 . 6 , 72 . 7 , 66 . 4 , 58 . 3 , 43 . 0 , 42 . 6 , 40 . 1 , 37 . 9 , 36 . 0 , 35 . 4 , 35 . 2 , 33 . 8 , 32 . 2 , 30 . 6 , 26 . 3 , 26 . 0 , 25 . 9 , 25 . 2 , 19 . 6 , 19 . 0 , 18 . 4 , 18 . 09 , 18 . 05 , 17 . 7 , 16 . 6 , 14 . 5 , 7 . 0 , − 2 . 8 , − 3 . 45 , − 3 . 54 , − 3 . 7 , − 4 . 1 , − 4 . 2 , − 4 . 4 ; lrms ( esi ) 1029 . 7 [ m + na ]+, 915 . 7 , 897 . 7 ; hrms ( esi ) calcd for c 56 h 110 o 7 si 4 na 1029 . 7226 [ m + na ]+, found 1029 . 7257 ; [ α ] 20 d − 41 . 7 ( c 1 . 4 , chcl 3 ). 8 ( s ), 10 ( s ), 14 ( r ), 20 ( r )- tetrakis ( tert - butyldimethylsilyloxy )- 7 ( s ), 13 ( s ), 15 ( r ), 17 ( s ), 21 ( s )- pentamethyl - 22 ( s )-( 1 ( s )- methylpenta - 2 , 4 - dienyl ) oxacyclodocosa - 3 , 5 , 11 - trien - 2 - one ( 99 ). a solution of above acid 98 in thf ( 2 ml ) was treated at 0 ° c . with et 3 n ( 0 . 10 ml , 0 . 72 μmol ) and 2 , 4 , 6 - trichlorobenzoyl chloride ( 0 . 095 ml , 0 . 60 μmol ). the reaction mixture was stirred at 0 ° c . for 30 min and then added to 4 - dmap ( 60 ml , 0 . 02 m solution in toluene ) at 25 ° c . and stirred overnight . the reaction mixture was concentrated , et 2 o ( 10 ml ) was added and the crude was washed with 0 . 5 n hcl ( 2 × 10 ml ), dried over mgso 4 . purification by flash column chromatography ( etoac / hexane 2 : 98 ) furnished macrolactone 99 ( 93 mg , 78 % for 2 steps ) as a colorless oil : ir ( chcl 3 ) 2957 , 2929 , 2856 , 1745 , 1715 , 1581 , 1471 , 1369 , 1270 , 1117 , 1082 , 836 , 773 cm 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 11 ( dd , j = 15 . 3 , 10 . 5 hz , 1h ), 6 . 59 ( ddd , j = 16 . 8 , 10 . 7 , 10 . 5 hz , 1h ), 6 . 22 ( dd , j = 15 . 4 , 6 . 0 hz , 1h ), 6 . 07 ( dd , j = 15 . 4 , 10 . 6 hz , 1h ), 5 . 92 ( t , j = 10 . 9 hz , 1h ), 5 . 70 ( d , j = 15 . 4 hz , 1h ), 5 . 46 ( t , j = 10 . 5 hz , 1h ), 5 . 35 - 5 . 27 ( m , 2h ), 5 . 20 ( d , j = 8 . 4 hz , 1h ), 5 . 12 ( d , j = 16 . 8 hz , 1h ), 5 . 04 ( d , j = 10 . 3 hz , 1h ), 4 . 53 ( m , 1h ), 3 . 91 ( m , 1h ), 3 . 41 ( m , 1h ), 3 . 19 ( m , 1h ), 2 . 94 ( m , 1h ), 2 . 55 ( m , 2h ), 1 . 94 ( m , 1h ), 1 . 40 - 1 . 29 ( m , 3h ), 1 . 26 - 1 . 15 ( m , 3h ), 1 . 00 - 0 . 85 ( m , 52h ), 0 . 74 ( d , j = 6 . 7 hz , 3h ), 0 . 63 ( d , j = 6 . 2 hz , 3h ), 0 . 08 - 0 . 00 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 9 , 144 . 93 , 144 . 88 , 136 . 0 , 135 . 0 , 133 . 5 , 132 . 4 , 130 . 7 , 129 . 3 , 120 . 2 , 117 . 2 , 80 . 3 , 75 . 7 , 73 . 9 , 72 . 7 , 66 . 3 , 42 . 4 , 41 . 0 , 40 . 6 , 39 . 3 , 36 . 5 , 35 . 8 , 35 . 1 , 34 . 5 , 31 . 9 , 29 . 7 , 26 . 2 , 26 . 0 , 25 . 9 , 21 . 6 , 19 . 8 , 19 . 7 , 18 . 4 , 18 . 11 , 18 . 07 , 17 . 9 , 14 . 9 , 11 . 3 , − 2 . 6 , − 3 . 6 , − 3 . 8 , − 4 . 2 , − 4 . 5 , − 4 . 6 ; lrms ( esi ) 1011 . 8 [ m + na ]+, 857 . 7 , 725 . 6 , 633 . 2 , 413 . 3 , 375 . 3 ; hrms ( esi ) calcd for c 56 h 108 o 6 si 4 na 1011 . 7121 [ m + na ]+, found 1011 . 7148 ; [ α ] 20 d − 16 . 9 ( c 1 . 24 , chcl 3 ). 3 n hcl ( 10 ml , prepared by adding 2 . 5 ml of conc . hcl to 7 . 5 ml meoh ) was added to a stirred solution of the above macrolactone 99 ( 61 mg , 6 . 17 μmol ) in thf ( 3 ml ) at 0 ° c . after 24 h at room temperature , the reaction mixture was diluted with etoac ( 4 ml ) and h 2 o ( 4 ml ) and the organic phase was separated and aqueous phase was extracted with etoac ( 2 × 4 ml ). the combined organic phases were washed with sat &# 39 ; d nahco 3 ( 10 ml ), dried with mgso 4 , concentrated and the residue was purified by flash chromatography ( etoac / hexane 3 : 2 ) to yield the product 100 ( 8 . 2 mg , 25 %) as a colorless oil : ir ( chcl 3 ) 3404 , 2962 , 2916 , 1692 , 1639 , 1455 , 1244 , 1061 , 1001 cm − 1 ; 1 h nmr ( 600 mhz , cd 3 od ) δ 7 . 15 ( dd , j = 15 . 3 , 10 . 5 hz , 1h ), 6 . 64 ( ddd , j = 16 . 8 , 10 . 6 , 10 . 3 hz , 1h ), 6 . 29 ( dd , j = 15 . 4 , 6 . 3 hz , 1h ), 6 . 22 ( dd , j = 15 . 5 , 10 . 5 hz , 1h ), 5 . 92 ( t , j = 10 . 9 hz , 1h ), 5 . 72 ( d , j = 15 . 3 hz , 1h ), 5 . 44 - 5 . 37 ( m , 2h ), 5 . 25 ( t , j = 10 . 3 hz , 1h ), 5 . 13 ( dd , j = 16 . 8 , 1 . 8 hz , 1h ), 5 . 06 ( d , j = 10 . 8 hz , 1h ), 5 . 04 ( dd , j = 9 . 1 , 1 . 8 hz , 1h ), 4 . 68 ( ddd , j = 9 . 9 , 7 . 2 , 2 . 4 hz , 1h ), 3 . 82 ( ddd , j = 9 . 2 , 6 . 2 , 2 . 7 hz , 1h ), 3 . 40 ( ddd , j = 10 . 2 , 6 . 2 , 2 . 3 hz , 1h ), 3 . 06 ( m , 1h ), 2 . 99 ( dd , j = 8 . 0 , 3 . 3 hz , 1h ), 2 . 62 ( m , 1h ), 2 . 58 ( m , 1h ), 1 . 88 ( m , 1h ), 1 . 62 ( m , 1h ), 1 . 55 ( ddd , j = 14 . 0 , 10 . 5 , 2 . 7 hz , 1h ), 1 . 38 ( ddd , j = 12 . 3 , 9 . 6 , 2 . 7 hz , 1h ), 1 . 34 - 1 . 23 ( m , 4h ), 1 . 12 ( d , j = 7 . 0 hz , 3h ), 1 . 06 ( d , j = 6 . 9 hz , 3h ), 1 . 04 ( d , j = 6 . 9 hz , 3h ), 1 . 00 ( d , j = 6 . 7 hz , 3h ), 0 . 95 - 0 . 88 ( m , 2h ), 0 . 87 - 0 . 82 ( m , 1h ), 0 . 79 ( d , j = 5 . 3 hz , 3h ), 0 . 68 ( d , j = 6 . 7 hz , 3h ); 3 c nmr ( 150 mhz , cd 3 0d ) δ 168 . 5 , 147 . 7 , 147 . 4 , 135 . 7 , 134 . 4 , 133 . 6 , 131 . 7 , 130 . 8 , 129 . 1 , 120 . 7 , 118 . 0 , 80 . 7 , 76 . 9 , 74 . 2 , 72 . 8 , 65 . 9 , 44 . 0 , 42 . 5 , 40 . 9 , 39 . 5 , 36 . 5 , 36 . 3 , 36 . 1 , 35 . 5 , 31 . 7 , 31 . 2 , 21 . 1 , 19 . 0 , 17 . 9 , 17 . 7 , 15 . 7 , 11 . 3 ; lrms ( esi ) 555 . 6 [ m + na ]+, 541 . 4 ; hrms ( esi ) calcd for c 32 h 52 o 6 555 . 3662 [ m + na ]+, found 555 . 3684 ; [ α ] 20 d − 6 . 5 ( c 0 . 17 , meoh ). the same procedure for 92 was used with above 91α ( 0 . 60 g , 0 . 50 μmol ), tbsotf ( 0 . 17 ml , 0 . 75 mmol ) and 2 , 6 - lutidine ( 0 . 12 ml , 1 . 0 mmol ) to yield 0 . 61 g ( 93 %) of the product by flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2928 , 2856 , 1518 , 1471 , 1462 , 1251 , 1075 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 56 - 7 . 48 ( m , 8h ), 7 . 38 - 7 . 26 ( m , 9h ), 6 . 97 - 6 . 94 ( m , 1h ), 5 . 91 ( dd , j = 15 . 6 , 5 . 9 hz , 1h ), 5 . 63 ( dt , j = 15 . 7 , 5 . 3 hz , 1h ), 5 . 58 - 5 . 50 ( m , 1h ), 5 . 52 ( s , 1h ), 5 . 41 ( dd , j = 10 . 8 , 8 . 6 hz , 1h ), 4 . 65 ( m , 1h ), 4 . 19 ( dd , j = 11 . 1 , 4 . 5 hz , 1h ), 4 . 01 ( m , 1h ), 3 . 90 ( m , 1h ), 3 . 84 ( s , 3h ), 3 . 66 ( d , j = 5 . 0 hz , 2h ), 3 . 56 ( t , j = 11 . 1 hz , 1h ), 3 . 36 ( m , 1h ), 2 . 71 ( m 1h ), 2 . 48 ( m , 1h ), 2 . 12 ( m , 1h ), 1 . 88 ( m , 1h ), 1 . 76 - 1 . 56 ( m , 3h ), 1 . 52 - 1 . 42 ( m , 2h ), 1 . 40 - 1 . 31 ( m , 2h ), 1 . 09 ( d , j = 7 . 7 hz , 3h ), 1 . 07 ( d , j = 7 . 5 hz , 3h ), 1 . 05 - 0 . 94 ( m , 42h ), 0 . 93 - 0 . 90 ( m , 2h ), 0 . 86 ( d , j = 6 . 6 hz , 3h ), 0 . 81 ( d , j = 6 . 3 hz , 3h ), 0 . 21 - 0 . 13 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 7 , 144 . 6 , 144 . 4 , 134 . 4 , 133 . 0 , 131 . 9 , 131 . 8 , 128 . 7 , 127 . 7 , 127 . 3 , 126 . 8 , 126 . 4 , 113 . 4 , 100 . 8 , 86 . 7 , 81 . 6 , 81 . 3 , 73 . 4 , 72 . 8 , 72 . 0 , 66 . 6 , 65 . 2 , 55 . 1 , 43 . 1 , 42 . 3 , 39 . 7 , 38 . 2 , 35 . 4 , 35 . 3 , 31 . 3 , 30 . 8 , 30 . 7 , 30 . 3 , 26 . 2 , 26 . 1 , 26 . 04 , 25 . 97 , 19 . 5 , 18 . 8 , 18 . 4 , 18 . 1 , 16 . 6 , 14 . 6 , 12 . 2 , 9 . 1 , − 2 . 8 , − 3 . 4 , − 3 . 6 , − 3 . 9 , − 4 . 0 , − 4 . 1 , − 4 . 3 ; lrms ( esi ) 1327 . 9 [ m + na ]+, 1037 . 9 , 803 . 6 , 647 . 6 , 619 . 6 , 413 . 3 , 359 . 2 , 229 . 1 ; hrms ( esi ) calcd for c 78 h 128 o 8 si 4 na 1327 . 8584 [ m + na ]+, found 1327 . 8622 ; [ α ] 20 d + 5 . 9 ( c 0 . 3 , chcl 3 ). the procedure for 93 was used with 101 ( 0 . 61 g , 0 . 47 μmol ), dibal ( 4 . 6 ml , 4 . 6 mmol ) to yield 0 . 53 g ( 87 %) of the product by flash column chromatography ( etoac / hexane 0 . 5 : 9 . 5 ) as a colorless oil : ir ( chcl 3 ) 3453 , 2956 , 2929 , 1514 , 1471 , 1251 , 1075 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 56 - 7 . 52 ( m , 6h ), 7 . 38 - 7 . 26 ( m , 11h ), 6 . 96 - 6 . 93 ( m , 2h ), 5 . 91 ( dd , j = 15 . 7 , 6 . 0 hz , 1h ), 5 . 64 ( dt , j = 15 . 4 , 5 . 5 hz , 1h ), 5 . 55 - 5 . 50 ( m , 1h ), 5 . 42 ( dd , j = 11 . 1 , 8 . 4 hz , 1h ), 4 . 70 - 4 . 58 ( m , 3h ), 4 . 01 ( m , 1h ), 3 . 83 ( s , 3h ), 3 . 79 ( m , 2h ), 3 . 67 - 3 . 61 ( m , 3h ), 3 . 35 ( m , 1h ), 3 . 30 ( m 1h ), 2 . 72 ( m , 1h ), 2 . 48 ( m , 1h ), 1 . 93 ( m , 2h ), 1 . 76 - 1 . 55 ( m , 3h ), 1 . 51 - 1 . 26 ( m , 1h ), 1 . 10 ( d , j = 6 . 6 hz , 3h ), 1 . 09 ( d , j = 6 . 6 hz , 3h ), 1 . 07 ( d , j = 6 . 7 hz , 3h ), 1 . 01 - 0 . 98 ( m , 39h ), 0 . 93 - 0 . 89 ( m , 2h ), 0 . 86 ( d , j = 6 . 6 hz , 3h ), 0 . 78 ( d , j = 4 . 6 hz , 3h ), 0 . 21 - 0 . 13 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 2 , 144 . 5 , 144 . 4 , 134 . 3 , 133 . 1 , 131 . 7 , 130 . 6 , 129 . 1 , 128 . 6 , 127 . 6 , 126 . 8 , 126 . 7 , 126 . 4 , 113 . 8 , 86 . 7 , 85 . 1 , 81 . 3 , 74 . 9 , 74 . 4 , 72 . 8 , 66 . 5 , 65 . 9 , 65 . 1 , 55 . 1 , 43 . 0 , 42 . 3 , 41 . 8 , 40 . 1 , 38 . 4 , 35 . 3 , 35 . 1 , 32 . 8 , 30 . 7 , 30 . 5 , 26 . 2 , 26 . 1 , 26 . 0 , 25 . 9 , 19 . 5 , 18 . 6 , 18 . 4 , 18 . 13 , 18 . 10 , 16 . 5 , 15 . 4 , 14 . 6 , 10 . 5 , − 2 . 8 , − 3 . 4 , − 3 . 6 , − 3 . 9 , − 4 . 0 , − 4 . 2 , − 4 . 4 ; lrms ( esi ) 1329 . 8 [ m + na ]+, 801 . 6 , 659 . 3 , 637 . 3 , 437 . 2 , 243 . 1 ; hrms ( esi ) calcd for c 78 h 130 o 8 si 4 na 1329 . 8741 [ m + na ]+, found 1329 . 8788 ; [ α ] 20 d − 9 . 8 ( c 2 . 6 , chcl 3 ). (( 2e , 4s , 5s , 7s , 8z , 10s , 11r , 12r , 14s , 17s , 18r , 19s , 20s , 21z )- 19 -( 4 - methoxybenzyloxy )- 5 , 7 , 11 , 17 - tetrakis ( tert - butyldimethylsilyloxy )- 4 , 10 , 12 , 14 , 18 , 20 - hexamethyltetracosa - 2 , 8 , 21 , 23 - tetraenyloxy ) triphenylmethane ( 103 ). the procedure for 94 was used with 102 ( 0 . 52 g , 0 . 40 μmol ), dess - martin reagent ( 0 . 25 g , 0 . 59 mmol ) and 1 - bromoallyl trimethylsilane ( 0 . 49 g , 2 . 0 mmol ), crcl 2 ( 0 . 41 g , 3 . 32 mmol ) and nah ( 0 . 20 g , 8 . 0 mmol ) to yield 0 . 46 g ( 88 %) of the product by flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2856 , 1614 , 1514 , 1471 , 1249 , 1074 , 835 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 59 - 7 . 56 ( m , 6h ), 7 . 41 - 7 . 27 ( m , 1h ), 6 . 98 - 6 . 95 ( m , 2h ), 6 . 71 ( ddd , j = 16 . 7 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 14 ( t , j = 11 . 0 hz , 1h ), 5 . 94 ( dd , j = 15 . 6 , 5 . 6 hz , 1h ), 5 . 80 - 5 . 67 ( m , 2h ), 5 . 64 - 5 . 55 ( m , 1h ), 5 . 46 ( dd , j = 11 . 0 , 8 . 5 hz , 1h ), 5 . 31 ( d , j = 16 . 8 hz , 1h ), 5 . 21 ( d , j = 10 . 2 hz , 1h ), 4 . 70 - 4 . 62 ( m , 3h ), 4 . 04 ( m , 1h ), 3 . 86 ( s , 3h ), 3 . 69 ( d , j = 4 . 7 hz , 1h ), 3 . 34 ( m , 2h ), 2 . 96 ( m , 1h ), 2 . 77 ( m , 1h ), 2 . 51 ( m , 1h ), 1 . 93 ( m , 1h ), 1 . 78 ( m , 1h ), 1 . 75 - 1 . 63 ( m , 3h ), 1 . 57 - 1 . 31 ( m , 5h ), 1 . 21 ( d , j = 6 . 7 hz , 3h ), 1 . 15 ( d , j = 6 . 1 hz , 3h ), 1 . 12 ( d , j = 6 . 7 hz , 3h ), 1 . 00 ( d , j = 7 . 3 hz , 3h ), 1 . 05 - 1 . 01 ( m , 36h ), 0 . 96 - 0 . 93 ( m , 2h ), 0 . 89 ( d , j = 6 . 7 hz , 3h ), 0 . 81 ( d , j = 5 . 3 hz , 3h ), 0 . 25 - 0 . 11 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 1 , 146 . 2 , 144 . 6 , 144 . 4 , 134 . 4 , 134 . 3 , 132 . 2 , 131 . 3 , 130 . 2 , 129 . 0 , 128 . 7 , 127 . 7 , 126 . 8 , 126 . 5 , 117 . 5 , 113 . 7 , 86 . 7 , 84 . 9 , 81 . 4 , 74 . 9 , 73 . 1 , 72 . 9 , 66 . 6 , 65 . 2 , 55 . 1 , 43 . 1 , 42 . 9 , 42 . 3 , 40 . 4 , 35 . 9 , 35 . 6 , 35 . 3 , 35 . 1 , 34 . 5 , 30 . 2 , 29 . 4 , 26 . 3 , 26 . 1 , 26 . 0 , 19 . 6 , 18 . 8 , 18 . 6 , 18 . 5 , 18 . 2 , 18 . 14 , 18 . 11 , 16 . 5 , 14 . 7 , 10 . 5 , − 1 . 1 , − 2 . 8 , − 3 . 0 , − 3 . 3 , − 3 . 5 , − 3 . 9 , − 4 . 2 , − 4 . 3 ; lrms ( esi ) 1351 . 8 [ m + na ]+, 911 . 1 , 837 . 1 , 763 . 1 , 689 . 1 , 541 . 1 , 413 . 2 ; hrms ( esi ) calcd for c 81 h 132 o 7 si 4 na 1351 . 8948 [ m + na ]+, found 1351 . 8998 ; [ α ] 20 d − 9 . 3 ( c 1 . 5 , chcl 3 ). the procedure for 95 was used with 103 ( 0 . 33 g , 0 . 25 μmol ) and znbr ( 0 . 28 g , 1 . 25 mmol ) to yield 0 . 18 g ( 65 %) of the product by flash column chromatography ( etoac / hexane 1 : 9 ) as a colorless oil : ir ( chcl 3 ) 3417 , 2956 , 2856 , 1613 , 1514 , 1471 , 1250 , 1074 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 31 - 7 . 27 ( m , 2h ), 6 . 90 - 6 . 87 ( m , 2h ), 6 . 60 ( ddd , j = 16 . 9 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 04 ( t , j = 11 . 0 hz , 1h ), 5 . 81 ( dd , j = 15 . 7 , 5 . 9 hz , 1h ), 5 . 67 - 5 . 60 ( m , 2h ), 5 . 51 - 5 . 44 ( m , 1h ), 5 . 34 ( dd , j = 11 . 2 , 8 . 7 hz , 1h ), 5 . 21 ( d , j = 16 . 8 hz , 1h ), 5 . 12 ( d , j = 10 . 2 hz , 1h ), 4 . 60 - 4 . 52 ( m , 3h ), 4 . 10 ( d , j = 5 . 7 hz , 1h ), 3 . 91 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 59 ( m , 1h ), 3 . 31 - 3 . 23 ( m , 2h ), 2 . 86 ( m , 1h ), 2 . 65 ( m , 1h ), 2 . 40 ( m , 1h ), 1 . 82 ( m , 1h ), 1 . 66 - 1 . 42 ( m , 5h ), 1 . 36 - 1 . 20 ( m , 3h ), 1 . 11 ( d , j = 6 . 8 hz , 3h ), 1 . 03 ( d , j = 7 . 3 hz , 3h ), 1 . 01 ( d , j = 6 . 6 hz , 3h ), 0 . 99 ( d , j = 5 . 8 hz , 3h ), 0 . 94 - 0 . 89 ( m , 38h ), 0 . 84 ( d , j = 7 . 2 hz , 3h ), 0 . 82 ( d , j = 6 . 4 hz , 3h ), 0 . 13 - 0 . 00 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 159 . 0 , 135 . 0 , 134 . 5 , 133 . 2 , 132 . 2 , 131 . 5 , 131 . 4 , 129 . 1 , 129 . 0 , 128 . 7 , 117 . 4 , 113 . 7 , 84 . 8 , 81 . 4 , 74 . 8 , 73 . 1 , 72 . 7 , 66 . 5 , 64 . 1 , 55 . 2 , 42 . 8 , 42 . 7 , 42 . 0 , 40 . 4 , 35 . 9 , 35 . 4 , 35 . 2 , 34 . 4 , 30 . 3 , 29 . 4 , 26 . 3 , 26 . 03 , 26 . 97 , 25 . 95 , 19 . 6 , 18 . 7 , 18 . 6 , 18 . 5 , 18 . 1 , 16 . 6 , 14 . 7 , 10 . 5 , − 2 . 8 , − 3 . 4 , − 3 . 5 , − 4 . 0 , − 4 . 1 , − 4 . 2 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1109 . 8 [ m + na ]+, 707 . 2 , 633 . 2 , 541 . 1 , 429 . 1 , 355 . 1 ; hrms ( esi ) calcd for c 62 h 118 o 7 si 4 na 1109 . 7852 [ m + na ]+, found 1109 . 7874 ; [ α ] 20 d − 15 . 0 ( c 0 . 94 , chcl 3 ). the procedure for 96 was used with 104 ( 0 . 18 g , 0 . 16 μmol ), dess - martin reagent ( 0 . 10 g , 0 . 24 mmol ) and bis ( 2 , 2 , 2 - trifluoroethyl )-( methoxycarbonylmethyl ) phosphate ( 0 . 041 ml , 0 . 19 μmol ), 18 - crown - 6 ( 0 . 21 g , 0 . 19 mmol ) and khmds ( 0 . 39 ml , 0 . 19 mmol ) to yield 0 . 16 g ( 84 %) of the product by flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 2956 , 2929 , 2856 , 1721 , 1514 , 1462 , 1250 , 1174 , 1074 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 38 ( dd , j = 15 . 4 , 11 . 2 hz , 1h ), 7 . 32 - 7 . 29 ( m , 2h ), 6 . 91 - 6 . 86 ( m , 2h ), 6 . 60 ( ddd , j = 17 . 0 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 56 ( t , j = 11 . 3 hz , 1h ), 6 . 23 ( dd , j = 15 . 5 , 5 . 9 hz , 1h ), 6 . 05 ( t , j = 11 . 0 hz , 1h ), 5 . 68 - 5 . 56 ( m , 2h ), 5 . 50 - 5 . 43 ( m , 1h ), 5 . 38 - 5 . 31 ( m , 1h ), 5 . 23 ( d , j = 16 . 8 hz , 1h ), 5 . 12 ( d , j = 10 . 2 hz , 1h ), 4 . 61 - 4 . 52 ( m , 3h ), 3 . 98 ( m , 1h ), 3 . 81 ( s , 3h ), 3 . 73 ( s , 3h ), 3 . 59 ( m , 1h ), 3 . 29 - 3 . 23 ( m , 2h ), 2 . 86 ( m , 1h ), 2 . 68 - 2 . 59 ( m , 2h ), 1 . 83 ( m , 1h ), 1 . 63 - 1 . 51 ( m , 2h ), 1 . 49 - 1 . 35 ( m , 3h ), 1 . 34 - 1 . 22 ( m , 2h ), 1 . 12 ( d , j = 6 . 8 hz , 3h ), 1 . 07 ( d , j = 6 . 9 hz , 3h ), 1 . 03 ( d , j = 5 . 0 hz , 3h ), 1 . 01 ( d , j = 6 . 7 hz , 3h ), 0 . 94 - 0 . 89 ( m , 38h ), 0 . 84 ( d , j = 6 . 6 hz , 3h ), 0 . 80 ( d , j = 6 . 1 hz , 3h ), 0 . 14 - 0 . 00 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 159 . 1 , 147 . 2 , 145 . 7 , 134 . 4 , 133 . 2 , 132 . 2 , 131 . 6 , 131 . 4 , 129 . 2 , 129 . 0 , 126 . 4 , 117 . 5 , 115 . 2 , 113 . 7 , 84 . 7 , 81 . 5 , 74 . 9 , 73 . 0 , 72 . 7 , 66 . 4 , 55 . 2 , 50 . 9 , 42 . 9 , 42 . 8 , 42 . 6 , 40 . 3 , 35 . 9 , 35 . 4 , 35 . 2 , 34 . 4 , 30 . 4 , 29 . 5 , 26 . 3 , 26 . 03 , 25 . 98 , 19 . 6 , 18 . 8 , 18 . 7 , 18 . 5 , 18 . 1 , 16 . 7 , 14 . 5 , 10 . 5 , 2 . 8 , − 3 . 3 , − 3 . 5 , − 4 . 0 , − 4 . 1 , − 4 . 17 , − 4 . 22 , − 4 . 4 ; lrms ( esi ) 1163 . 8 [ m + na ]+, 1009 . 7 , 877 . 6 , 513 . 4 ; hrms ( esi ) calcd for c 65 h 120 o 8 si 4 na 1163 . 7958 [ m + na ]+, found 1163 . 7981 ; [ α ] 20 d − 45 . 3 ( c 0 . 36 , chcl 3 ) ( 2z , 4e , 6s , 7s , 9s , 10z , 12s , 13r , 14r , 16s , 19s , 20r , 21s , 22s , 23z )- methyl - 7 , 9 , 13 , 19 - tetrakis ( tert - butyldimethylsilyloxy )- 21 - hydroxy - 6 , 12 , 14 , 16 , 20 , 22 - hexamethylhexacosa - 2 , 4 , 10 , 23 , 25 - pentaenoate ( 106 ). the procedure for 97 was used with 105 ( 0 . 16 g , 0 . 14 μmol ) and ddq ( 0 . 034 g , 0 . 15 mmol ) to yield 0 . 13 g ( 90 %) of the product by flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ir ( chcl 3 ) 3512 , 2956 , 2929 , 2857 , 1772 , 1639 , 1471 , 1462 , 1255 , 1193 , 1076 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 35 ( dd , j = 15 . 4 , 11 . 2 hz , 1h ), 6 . 61 ( ddd , j = 16 . 9 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 53 ( t , j = 11 . 3 hz , 1h ), 6 . 19 ( dd , j = 15 . 6 , 6 . 0 hz , 1h ), 6 . 09 ( t , j = 11 . 0 hz , 1h ), 5 . 56 ( d , j = 11 . 3 hz , 1h ), 5 . 44 ( t , j = 11 . 0 hz , 1h ), 5 . 31 ( dd , j = 11 . 0 , 8 . 4 hz , 1h ), 5 . 19 ( d , j = 16 . 8 hz , 1h ), 5 . 10 ( d , j = 10 . 1 hz , 1h ), 4 . 55 ( m , 1h ), 3 . 94 ( m , 1h ), 3 . 71 ( s , 3h ), 3 . 25 ( m , 2h ), 2 . 75 ( m , 1h ), 2 . 58 ( m , 2h ), 1 . 72 ( m , 1h ), 1 . 67 - 1 . 60 ( m , 1h ), 1 . 59 - 1 . 49 ( m , 2h ), 1 . 40 ( m , 1h ), 1 . 32 - 1 . 25 ( m , 2h ), 1 . 22 - 1 . 13 ( m , 2h ), 1 . 04 ( d , j = 7 . 0 hz , 3h ), 1 . 01 ( d , j = 7 . 1 hz , 3h ), 0 . 99 ( d , j = 6 . 8 hz , 3h ), 0 . 91 - 0 . 86 ( m , 41h ), 0 . 81 ( d , j = 6 . 5 hz , 3h ), 0 . 79 ( d , j = 6 . 0 hz , 3h ), 0 . 11 - 0 . 05 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 166 . 8 , 147 . 2 , 145 . 6 , 136 . 4 , 133 . 2 , 132 . 6 , 131 . 5 , 129 . 5 , 126 . 4 , 117 . 3 , 115 . 2 , 81 . 3 , 78 . 6 , 74 . 3 , 72 . 7 , 66 . 4 , 50 . 9 , 42 . 9 , 42 . 6 , 39 . 7 , 36 . 2 , 35 . 8 , 35 . 4 , 35 . 3 , 34 . 1 , 32 . 4 , 30 . 6 , 26 . 3 , 26 . 0 , 25 . 9 , 19 . 6 , 19 . 2 , 18 . 5 , 18 . 1 , 18 . 0 , 17 . 4 , 16 . 7 , 14 . 5 , 10 . 9 , − 2 . 8 , − 3 . 4 , − 3 . 5 , − 4 . 06 , − 4 . 11 , − 4 . 2 , − 4 . 3 , − 4 . 4 ; lrms ( esi ) 1043 . 7 [ m + na ]+; hrms ( esi ) calcd for c 57 h112o 7 si 4 na 1043 . 7383 [ m + na ]+, found 1043 . 7424 ; [ α ] 21 d − 37 . 8 ( c 1 . 4 , chcl 3 ). the procedure for 99 was used with 106 ( 0 . 13 g , 0 . 13 μmol ) and 1n koh ( 1 . 2 ml , 1 . 3 mmol ), 2 , 4 , 6 - trichlorobenzoyl chloride ( 0 . 094 ml , 0 . 60 μmol ) and et 3 n ( 0 . 10 ml , 0 . 78 mmol ), 4 - dmap ( 60 ml , 1 . 3 mmol ) to yield 0 . 054 g ( 45 % for 2 steps ) of the product by flash column chromatography ( etoac / hexane 1 : 19 ) as a colorless oil : ( seco acid ) ir ( chcl 3 ) 2956 , 2857 , 1692 , 1634 , 1471 , 1462 , 1254 , 1076 , 836 , 773 cm − 1 ; 1 h nmr ( 300 mhz , cdcl 3 ) δ 7 . 34 ( dd , j = 15 . 2 , 11 . 3 hz , 1h ), 6 . 66 ( ddd , j = 16 . 8 , 10 . 8 , 10 . 6 hz , 1h ), 6 . 62 ( t , j = 11 . 3 hz , 1h ), 6 . 23 ( dd , j = 15 . 3 , 6 . 0 hz , 1h ), 6 . 09 ( t , j = 11 . 0 hz , 1h ), 5 . 57 ( d , j = 11 . 2 hz , 1h ), 5 . 48 - 5 . 42 ( m , 1h ), 5 . 35 - 5 . 28 ( m , 1h ), 5 . 20 ( d , j = 16 . 8 hz , 1h ), 5 . 10 ( d , j = 10 . 2 hz , 1h ), 4 . 55 ( m , 1h ), 3 . 95 ( m , 1h ), 3 . 74 ( m , 1h ), 3 . 26 ( m , 1h ), 2 . 78 ( m , 1h ), 2 . 58 ( m , 2h ), 1 . 75 - 1 . 64 ( m , 2h ), 1 . 62 - 1 . 49 ( m , 3h ), 1 . 44 - 1 . 37 ( m , 1h ), 1 . 32 - 1 . 19 ( m , 3h ), 1 . 04 ( d , j = 7 . 0 hz , 3h ), 1 . 01 ( d , j = 7 . 0 hz , 3h ), 1 . 00 ( d , j = 6 . 4 hz , 3h ), 0 . 95 - 0 . 86 ( m , 41h ), 0 . 82 ( d , j = 7 . 1 hz , 3h ), 0 . 81 ( d , j = 6 . 4 hz , 3h ), 0 . 12 - 0 . 05 ( m , 24h ); 13 c nmr ( 75 mhz , cdcl 3 ) δ 171 . 5 , 148 . 3 , 147 . 4 , 136 . 4 , 133 . 1 , 132 . 6 , 131 . 5 , 129 . 5 , 126 . 6 , 117 . 3 , 115 . 0 , 81 . 3 , 78 . 6 , 74 . 3 , 72 . 7 , 66 . 4 , 43 . 0 , 42 . 7 , 39 . 7 , 36 . 2 , 35 . 8 , 35 . 5 , 35 . 3 , 34 . 1 , 32 . 4 , 30 . 6 , 26 . 3 , 26 . 0 , 25 . 94 , 25 . 92 , 19 . 6 , 19 . 2 , 18 . 5 , 18 . 1 , 18 . 0 , 17 . 4 , 16 . 7 , 14 . 5 , 11 . 0 , − 2 . 8 , − 3 . 4 , − 3 . 5 , − 4 . 1 , − 4 . 25 , − 4 . 32 , − 4 . 7 ; lrms ( esi ) 1029 . 7 [ m + na ]+, 915 . 8 ; hrms ( esi ) calcd for c 56 h 110 o 7 si 4 na 1029 . 7226 [ m + na ]+, found 1029 . 7252 ; [ α ] 20 d − 32 . 7 ( c 0 . 51 , chcl 3 ). the procedure for 100 was used with 107 ( 0 . 054 g , 0 . 054 μmol ) in 3n hcl ( 5 ml ) and thf ( 2 ml ) to yield 13 mg ( 45 %) of 108 and 4 . 5 mg ( 15 %) of the 109 by flash column chromatography ( etoac / hexane 7 : 3 ) as a colorless oil : ( 108 ) ir ( chcl 3 ) 3416 , 2961 , 2927 , 2873 , 1692 , 1635 , 1455 , 1421 , 1379 , 1190 , 1086 , 998 cm − 1 ; 1 h nmr ( 600 mhz , cd 3 od ) δ 7 . 26 ( dd , j = 15 . 2 , 11 . 3 hz , 1h ), 6 . 65 ( ddd , j = 16 . 8 , 10 . 6 , 10 . 3 hz , 1h ), 6 . 56 ( t , j = 11 . 3 hz , 1h ), 5 . 97 ( t , j = 10 . 9 hz , 1h ), 5 . 91 ( dd , j = 15 . 2 , 9 . 3 hz , 1h ), 5 . 49 ( d , j = 10 . 7 hz , 1h ), 5 . 42 ( t , j = 8 . 6 hz , 1h ), 5 . 20 ( t , j = 10 . 4 hz , 1h ), 5 . 15 ( dd , j = 16 . 9 , 1 . 3 hz , 1h ), 5 . 08 ( d , j = 10 . 1 hz , 1h ), 5 . 05 ( dd , j = 9 . 6 , 1 . 3 hz , 1h ), 4 . 62 ( ddd , j = 11 . 5 , 7 . 7 , 4 . 3 hz , 1h ), 3 . 65 ( ddd , j = 10 . 0 , 7 . 3 , 3 . 1 hz , 1h ), 3 . 07 ( dd , j = 6 . 7 , 4 . 0 hz , 1h ), 3 . 01 ( m , 1h ), 2 . 66 ( m , 1h ), 2 . 26 ( m , 1h ), 1 . 90 ( m , 1h ), 1 . 66 ( ddd , j = 11 . 5 , 8 . 4 , 3 . 4 hz , 1h ), 1 . 49 ( ddd , j = 14 . 1 , 10 . 0 , 4 . 0 hz , 1h ), 1 . 45 ( m , 1h ), 1 . 38 ( m , 1h ), 1 . 32 ( m , 1h ), 1 . 27 ( m , 1h ), 1 . 11 ( d , j = 6 . 7 hz , 3h ), 1 . 06 ( m , 1h ), 1 . 03 ( ddd , j = 11 . 3 , 7 . 2 , 4 . 4 hz , 3h ), 1 . 01 ( d , j = 6 . 9 hz , 3h ), 0 . 99 ( d , j = 6 . 7 hz , 3h ), 0 . 96 ( d , j = 7 . 0 hz , 3h ), 0 . 93 ( m , 1h ), 0 . 89 ( m , 1h ), 0 . 85 ( d , j = 6 . 7 hz , 3h ), 0 . 75 ( d , j = 5 . 9 hz , 3h ); 13 c nmr ( 150 mhz , cd 3 od ) δ 168 . 1 , 148 . 7 , 146 . 6 , 135 . 7 , 134 . 0 , 133 . 7 , 132 . 9 , 131 . 1 , 128 . 2 , 118 . 0 , 117 . 0 , 80 . 9 , 78 . 4 , 74 . 4 , 72 . 4 , 66 . 3 , 46 . 4 , 43 . 4 , 42 . 5 , 40 . 9 , 36 . 3 , 35 . 90 , 35 . 88 , 35 . 7 , 31 . 8 , 31 . 5 , 19 . 9 , 19 . 3 , 18 . 3 , 17 . 5 , 8 . 5 ; lrms ( esi ) 555 . 3 [ m + na ]+, 537 . 4 ; hrms ( esi ) calcd for c 32 h 52 o 6 555 . 3662 [ m + na ]+, found 555 . 3680 ; [ α ] 20 d + 76 . 5 ( c 0 . 52 , meoh ): ( 109 ) ir ( chcl 3 ) 3428 , 2962 , 2928 , 1690 , 1635 , 1380 , 1243 , 1145 , 1064 , 1000 cm − 1 ; 1 h nmr ( 600 mhz , cd 3 od ) δ 7 . 20 ( dd , j = 15 . 2 , 10 . 8 hz , 1h ), 6 . 65 ( ddd , j = 17 . 0 , 10 . 6 , 10 . 5 hz , 1h ), 6 . 38 ( dd , j = 15 . 5 , 5 . 4 hz , 1h ), 6 . 23 ( dd , j = 14 . 4 , 10 . 9 hz , 1h ), 5 . 95 ( t , j = 11 . 0 hz , 1h ), 5 . 77 ( d , j = 15 . 3 hz , 1h ), 5 . 40 - 5 . 39 ( m , 2h ), 5 . 23 ( t , j = 10 . 5 hz , 1h ), 5 . 13 ( d , j = 18 . 1 hz , 1h ), 5 . 12 ( dd , j = 8 . 2 , 1 . 5 hz , 1h ), 5 . 07 ( d , j = 10 . 2 hz , 1h ), 4 . 66 ( m , 1h ), 3 . 90 ( ddd , j = 7 . 6 , 5 . 1 , 2 . 5 hz , 1h ), 3 . 22 ( dd , j = 9 . 8 , 7 . 9 hz , 1h ), 3 . 04 ( m , 1h ), 2 . 95 ( dd , j = 9 . 7 , 2 . 1 hz , 1h ), 2 . 72 ( m , 1h ), 2 . 65 ( m , 1h ), 1 . 83 ( m , 1h ), 1 . 58 ( m , 1h ), 1 . 46 ( m , 1h ), 1 . 35 - 1 . 23 ( m , 4h ), 1 . 05 ( d , j = 6 . 8 hz , 3h ), 1 . 04 ( d , j = 6 . 9 hz , 3h ), 0 . 98 ( d , j = 6 . 8 hz , 3h ), 0 . 97 ( d , j = 7 . 0 hz , 3h ), 0 . 94 ( m , 2h ), 0 . 78 ( m , 1h ), 0 . 71 ( d , j = 6 . 4 hz , 3h ), 0 . 68 ( d , j = 6 . 5 hz , 3h ); 13 c nmr ( 150 mhz , cd 3 od ) δ 169 . 4 , 147 . 5 , 147 . 4 , 135 . 9 , 134 . 3 , 133 . 7 , 131 . 0 , 128 . 9 , 120 . 0 , 118 . 0 , 80 . 5 , 78 . 5 , 72 . 6 , 72 . 0 , 65 . 2 , 43 . 6 , 42 . 6 , 42 . 1 , 39 . 3 , 36 . 3 , 35 . 8 , 35 . 6 , 35 . 3 , 31 . 4 , 29 . 7 , 19 . 3 , 18 . 5 , 17 . 4 , 17 . 1 , 14 . 8 , 9 . 0 ; lrms ( esi ) 555 . 5 [ m + na ]+; hrms ( esi ) calcd for c 32 h 52 o 6 555 . 3662 [ m + na ]+, found 555 . 3687 ; [ α ] 20 d − 17 . 3 ( c 0 . 15 , meoh ). tubulin assembly was monitored turbidimetrically in gilford 250 spectrophotometers equipped with electronic temperature controllers as described previously ( ter haar et al ., 1996 ). the reaction mixtures without the compounds consisted of tubulin ( 1 mg / ml ), heat - treated maps ( 0 . 75 mg / ml , if present ), gtp ( 100 μm , if present ), and 0 . 1m ( 4 - morpholinyl ) ethane sulfonate ( mes ). baselines were established after addition of all reaction components except the compounds to the cuvettes held at 0 ° c . compounds , at 10 μm or 40 μm final concentration , were then added and each reaction mixture ( 0 . 25 ml final volume ) was subjected to the indicated temperature changes . the effects of dictyostatin and its analogs on growth inhibition of parental ( a549 ) and paclitaxel - resistant ( 1a9 / ptx10 and ptx22 ) ovarian adenocarcinoma cell lines were evaluated following the antiproliferative assay protocol as described earlier ( minguez et al ., 2003 ; choy et al ., 2003 ; lazo et al ., 2001 ). cells were maintained in rpmi medium with 10 % fbs in it , plated in tissue culture plates , and allowed to grow for 48 - 72 h before transferring them into 96 - well plates . cells were allowed to attach and grow for 48 h in 96 - well plates after which they were treated with either control ( dmso ) or drug in triplicate / quadruplicate . cells were incubated with the compounds for 72 h . cells were treated with mts reagent before reading the plate in a dynamax plate reader for determining the cell number . the fifty percent growth inhibition values ( gi 50 values ) were calculated for the compounds against all the three cell lines . the assay was performed under three different reaction conditions following the procedure reported earlier ( gapud et al ., 2004 ). reaction condition 1 included 0 . 2 m monosodium glutamate ( msg ), 10 μm tubulin , 5 % dmso and varying concentrations of test agents . reaction condition 2 included 0 . 8 m msg , 400 μm gtp , 10 μm tubulin , 5 % dmso , and varying concentrations of test agents . reaction condition 3 had 0 . 6 m msg , 200 μm gtp , and 10 μm tubulin , and 5 % dmso , and varying concentrations of the test agents . the experimental protocol for all the three reaction conditions was the following . the reaction mixtures were incubated at room temperature ( 20 - 22 ° c .) for 15 min and spun for 10 min at 14 , 000 rpm in an eppendorf microtube centrifuge . aliquots of the supernatants were removed and assayed for protein content by the method of lowry . the ec 50 was defined as drug concentration required to polymerize 50 % of tubulin compared to the pellet found in the dmso control reaction determined for each test system . on average 5 . 5 ± 4 . 0 % of the tubulin pelleted in the dmso control . hela cells growing at log phase were trypsinized and plated in 40 μl at a density of 7 , 000 - 8 , 000 cells per well in calf skin collagen i - coated 384 - well plates ( falcon # 3962 ; fisher scientific ). cells were exposed to test agents or 0 . 5 % dmso within 2 - 8 h of plating . concentrated dmso stock solutions of all test agents were diluted into solutions of hbss medium plus 10 % fbs and added to the microplate wells ( 10 μl per well ), using an automated liquid handling system ( biomek ® 2000 ; beckman - coulter , inc .) to provide a serial 2 - fold dilution of each test agent . the cells were incubated in the presence of test agents for 24 h . at the end of the incubation , the medium was removed and replaced with hbss containing 4 % formaldehyde and 10 μg / ml hoechst 33342 ( 25 μl / well ) to fix the cells and fluorescently label their chromatin . after incubation at room temperature for 20 - 30 min , the solution was removed from each well and replaced with hbss ( 100 μl / well ). further reagent additions were made to the microplates using the biomek 2000 . after removing the hbss from each well , cells were permeabilized for 5 min at room temperature with 0 . 5 % ( w / w ) triton x - 100 in hbss ( 10 μl / well ). this step extracts a fraction of the soluble cellular components , including soluble tubulin . the wells were washed with hbss ( 100 μl / well ), followed by addition of a primary antibody solution containing mouse anti - α - tubulin ( 1 : 3000 ) and rabbit anti - phosphohistone h3 ( 1 : 500 ) in hbss ( 10 μl / well ). after 1 h at room temperature , the wells were washed with hbss as above , followed by the addition of a secondary antibody solution containing fluorescein - 5 - isothiocyanate ( fitc )- labeled donkey anti - mouse ( 1 : 300 ) and cy3 - labeled donkey anti - rabbit ( 1 : 300 ) antibodies diluted in hbss ( 10 μl / well ). after 1 h at room temperature , the wells were washed as above , and hbss was added ( 100 μl / well ). the plates were placed in an arrayscan ® hcs reader with the target activation bioapplication software coupled to cellomics ® store and the vhcs ™ discovery toolbox ( cellomics , inc .) to analyze images . briefly , the instrument was used to scan multiple optical fields , each with multiparameter fluorescence , within a subset of the wells of the 384 - well microplate . the bioapplication software produced multiple numerical feature values , such as subcellular object intensities , shapes , and location for each cell within an optical field . data were acquired from a minimum of 1 , 000 cells per well , except in cases where added test agents reduced the attachment of cells to the substrate . a nuclear mask was generated from hoechst 33342 - stained nuclei , and object identification thresholds and shape parameters were set such that the algorithm identified over 90 % of the nuclei in each field . objects that touched each other or the edge of the image were excluded from the analysis . tubulin mass was defined as the average green ( fitc ) pixel intensity in an area defined by the hoechst - defined nuclear mask . this cytoplasmic area around the nucleus contains cytoskeletal components is a region from which sensitive measurements of cytoplasmic characteristics can be made . the percentage of phospho - histone h3 positive cells was defined as the number of cells whose average red ( cy3 ) staining intensity exceeded the average cy3 intensity plus two standard deviations of vehicle - treated cells , divided by the total number of cells . [ 3 h ] paclitaxel , [ 3 h ] discodermolide and [ 14 c ] epothilone b solutions were prepared as 125 μm stock solutions in 50 % dmso . radiolabeled compound ( final concentration , 4 . 0 μm ) and test agents at final concentrations noted in the text and tables were mixed in 50 μl of 4 : 1 ( v / v ) 0 . 75 m aqueous msg / dmso and warmed to 37 ° c . meanwhile , a reaction mixture containing 0 . 75 m msg , 2 . 5 μm tubulin , and 25 μm ddgtp was prepared and incubated at 37 ° c . for 30 min to form microtubuless . a 200 μl aliquot of the microtubule mixture was added to the drug mixtures , and incubation continued for 30 min at 37 ° c . reaction mixtures were centrifuged in an eppendorf 5417c centrifuge at 14 , 000 rpm for 20 min at room temperature . radiolabel in the supernatants ( 100 μl ) was determined by scintillation spectrometry . bound radiolabeled compound was calculated from the total radiolabel added to each reaction mixture minus the amount of radiolabel found in the supernatant . the foregoing description and accompanying drawings set forth the preferred embodiments of the invention at the present time . various modifications , additions and alternative designs will , of course , become apparent to those skilled in the art in light of the foregoing teachings without departing from the scope of the invention . the scope of the invention is indicated by the following claims rather than by the foregoing description . all changes and variations that fall within the meaning and range of equivalency of the claims are to be embraced within their scope .