text: 12 g of metal sodium ( or a same equivalent of sodium methoxide ) was slowly added to 46 . 8 g of phenylacetonitrile dissolved in 200 ml of dried methylalcohol . hence , the temperature was increased by 50 ° c . due to exothermic reaction . 47 . 2 g of dimethyloxalate was added to the mixture at the same temperature , cooled down to room temperature and stirred for 18 hours at room temperature . the reacting solution was cooled down by ice water and with the addition of 200 ml of 2n - sulfuric acid solution and then , methanol solvent only was concentrated under reduced pressure . the residue was extracted by ethyl acetate two times and dried over mgso 4 , while the solvent was concentrated under reduced pressure . normal hexane was added to a yellow crystal , so obtained , and after being filtered off , the residue was dried under vacuum to obtain 66 . 6 g of a desired compound ( yield : 82 %). mp 112 ˜ 114 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 1 . 25 - 1 . 78 ( s , 8h ), 2 . 04 - 2 . 27 ( m , 5h ), 3 . 58 ( s , 3h ), 6 . 99 ( bs , 1h ), 7 . 25 - 7 . 37 ( m , 5h ); ir ( chcl 3 ) 1242 , 1402 , 1736 , 2939 , 3070 , 3200 cm − 1 . the reaction was performed in the same manner as preparation example 1 except for using diethyloxalate instead of dimethyloxalate and ethanol as a reaction solvent , thus obtaining a desired compound in a yellow crystals ( yield : 75 %). mp 95 ˜ 97 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 1 . 51 ( t , j = 7 . 2 hz , 3h ), 4 . 53 ( ab − q , j = 7 . 2 hz , 2h ), 7 . 26 - 7 . 48 ( m , 3h ), 7 . 66 - 7 . 92 ( m , 2h ); ms ( 70 ev , m / e ) 217 ( m + ), 193 , 111 . the reaction was performed in the same manner as preparation example 2 except for using 4 - chlorophenylacetonitrile instead of phenylacetonitrile , thus obtaining a desired compound in a yellow crystals ( yield : 82 %). mp 105 ˜ 107 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 4 . 20 ( s , 3h ), 7 . 49 ( d , j = 7 . 6 hz , 2h ), 7 . 91 ( d , j = 7 . 8 hz , 2h ); ms ( 70 ev , m / e ) 237 ( m + ), 183 , 135 . the reaction was performed in the same manner as preparation example 2 except for using 4 - methoxyphenylacetonitrile instead of phenylacetonitrile , thus obtaining a desired compound in a yellow crystals ( yield : 87 %). mp 125 ˜ 127 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 3 . 77 ( s , 3h ), 4 . 00 ( s , 3h ), 6 . 85 ( d , j = 9 . 2 hz , 2h ), 7 . 76 ( d , j = 9 . 2 hz , 2h ); ms ( 70 ev , m / e ) 233 ( m + ), 173 , 145 . the reaction was performed in the same manner as preparation example 2 except for using 4 - nitrophenylacetonitrile instead of phenylacetonitrile , thus obtaining a desired compound in a bright yellow crystals ( yield : 35 %). mp 135 ˜ 137 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 3 . 82 ( s , 3h ), 7 . 48 ( d , j = 8 . 62 hz , 2h ), 8 . 18 ( d , j = 8 . 8 hz , 2h ); ms ( 70 ev , m / e ) 248 ( m + ). preparation of methyl 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester ( the general formula ( viii ) compound ) 52 . 5 g of methyl 3 - cyano - 3 - phenylpyruvic acid ester was added to 97 ml of glacial acetic acid , followed by the addition of 29 . 4 g of cyclohexanone and 32 . 7 ml of anhydrous acetic acid in order at 10 ° c . with the slow addition of 48 ml of concentrated sulfuric acid dissolved in 97 ml of glacial acetic acid at the same temperature , the reacting solution was stirred for 2 hours by gradually increasing the temperature to room temperature . the reacting solution was cooled down and with the addition of 100 ml of water , stirred for 10 minutes . the precipitation , so formed , was filtered off and washed with a mixing solution ( normal hexane : ethyl acetate = 1 : 1 ) and hexane , respectively . the residue was dried under vacuum to obtain 67 g of a pure desired compound in a pale yellow solid ( yield : 82 %). mp 170 ˜ 172 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 3 . 89 ( s , 3h ), 7 . 22 - 7 . 26 ( m , 5h ), 7 . 77 ( d , 1h ); ir ( chcl 3 ) 1438 , 1719 , 2224 , 3191 cm − 1 . as outlined in the following table 1 , the compounds were prepared in a manner such that each compound , so prepared by preparation examples and ketone compounds were reacted by preparation example 6 . 12 . 2 g of methyl 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester was dissolved in 60 ml of anhydrous tetrahydrofuran and after being cooled down to − 10 ° c ., 4 . 26 ml of pyridine and 5 . 52 ml of 2 - bromoacetyl bromide were slowly added to the above mixture . the reacting solution was stirred at room temperature for 6 hours and then , the reaction was terminated . the reacting solution was diluted with water and extracted two times by 100 ml of ethyl acetate each . the collected organic layer was washed with 10 % sodium bicarbonate solution , dried over mgso 4 and concentrated under reduced pressure . after 50 ml of isopropylalcohol was added to the residue , the mixture was stirred for a short time and then , crystals were formed . the crystals , so formed , filtered off and washed with 10 ml of isopropylalcohol each two times . after being washed with normal hexane , the residue was dried under vacuum to obtain 16 . 1 g of a desired compound in pale yellow solid ( yield : 92 %). mp 104 ˜ 105 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 1 . 11 - 12 . 66 ( m , 10h ), 1 . 84 ( d , j = 6 . 6 hz , 3h ), 3 . 64 ( s , 3h ), 5 . 06 ( q , j = 6 . 8 hz , 1h ), 7 . 21 - 7 . 41 ( m , 5h ); ir ( chcl 3 ) 1384 , 1445 , 1675 , 1631 , 1735 , 2866 , 2940 cm − 1 . the corresponding starting material and 2 - bromoacetylbromide were reacted by the same process of example 1 , thus preparation the compounds listed in the following table 2 . 5 g of ( 3r , 4r )- 4 - acetoxy - 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - azetidinone was dissolved in 60 ml of anhydrous tetrahydrofuran and with the addition of 3 . 41 g of zine powder , the mixture was refluxed for 20 minutes . the reacting solution was cooled down to room temperature and then , 8 . 33 g of methyl 5 -( 2 - bromopropionyl )- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester dissolved in 20 ml of anhydrous tetrahydrofuran was slowly added to the reacting solution . the solution was reheated and refluxed for 2 hours . the reacting solution was cooled down to room temperature and with the addition of phosphate buffer solution ( ph = 7 . 0 ), the insoluble material , so formed , was filtered off . the remaining solution was extracted with ethyl acetate two times . after the organic layer was dried over mgso 4 , the residue was purified on silica gel column chromatograpy ( elute ; ethyl acetate : hexane = 1 : 4 ) to obtain compound 9 . 92 g of a desired compound ( yield : 97 %). from the desired compound , so obtained , a mixture of stereoisomer 1 ′ r and 1 ′ s was present in 1 ′ position expressed by the above scheme , and as a result of analysis by hplc ( capcll park c - 18 column , elute ; acetonitrile : water = 7 : 3 ), the ratio between 1 ′ r isomer : 1 ′ s isomer was 95 : 5 . mp 68 ˜ 70 ° c . ; 1 h - nmr ( cdcl 3 , 200 mhz ) δ 0 . 00 ( s , 6h ), 0 . 80 ( s , 9h ), 1 . 11 ( d , j = 6 . 4 hz , 3h ), 1 . 16 ( d , j = 7 . 0 hz , 3h ), 1 . 52 - 1 . 81 ( m , 6h ), 2 . 02 - 2 . 41 ( m , 4h ), 2 . 79 - 2 . 82 ( m , 1h , 1 ′ s - h ), 3 . 12 - 3 . 16 ( m , 1h , 1 ′ r - h ), 3 . 12 - 3 . 16 ( m , 1 ), 3 . 37 - 3 . 44 ( m , 1h ), 3 . 57 ( s , 3h ), 3 . 85 - 3 . 89 ( m , 1h ), 5 . 09 ( s , 1h ), 7 . 13 - 7 . 21 ( m , 2h ), 7 . 25 - 7 . 35 ( m , 3h ); ir ( chcl 3 ) 1377 , 1447 , 1633 , 1678 , 1758 , 2857 , 2949 cm − 1 . the corresponding starting material and ( 3r , 4r )- 4 - acetoxy - 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - azetidinone were reacted by the same process of example 10 , thus preparing the compounds listed in the following table 3 . as another process for preparing the compound of example 10 , a small amount of iodine was added to 15 mg of anhydrous tetrahydrofuran and with the addition of 655 mg of magnesium piece , 1 . 13 g of 1 , 2 - dibromoethane was slowly added to the mixture . the temperature of the reacting solution was increased to reflux temperature due to exothermal reaction . then , 2 . 26 g of 1 , 2 - dibromoethane dissolved in 4 . 5 ml of tetrahydrofuran was slowly added to the solution and refluxed for 30 minutes . after the mixture was cooled down to 5 ° c ., 1 . 72 g of ( 3r , 4r )- 4 - acetoxy - 3 -[( ir )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - azetidinone and 2 . 88 g of methyl 5 -( 2 - bromopropionyl )- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester dissolved in 8 ml of tetrahydrofuran were slowly added to the mixture . the reacting solution was stirred at 10 ° c . for 1 hour and with the addition of 90 ml of saturated ammonium chloride , the reaction was terminated and extracted with ethyl acetate . the extract was washed with brine , dried over mgso 4 and concentrated under reduced pressure . the residue was purified on silica gel column chromatography ( elute ; ethyl acetate : hexane = 1 : 4 ) to obtain 3 . 07 g of a desired compound ( yield : 88 %). this compound was the same as example 2 and as a result of hplc ( the same conditions as example 10 ), the ratio of 1 ′ r - isomer : 1 ′ s - isomer was 98 : 2 . preparation of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 1 - allyloxycarboxylmethyl - 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester ( the general formula ( xi ) compound ) 5 . 0 g of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxoazetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester was dissolved in 50 ml of anhydrous tetrahydrofuran and cooled down to − 60 ° c . under the atmosphere of nitrogen gas , 1 . 53 g of allylbromoacetate and 9 . 76 ml of sodium bis ( trimethylsilyl ) amide ( 1 mol of tetrahydrofuran solution ) were slowly added to the mixture . the reacting solution was stirred at the same temperature for 15 minutes and with the gradual increase of temperature , the solution was further stirred at − 30 ° c . for 40 minutes . after water was added to the reacting solution , the solution was extracted with ethyl acetate , dried over mgso 4 and concentrated under reduced pressure . the residue was purified on silica gel column chromatography ( elute ; ethyl acetate : hexane = 1 : 4 ) to obtain 4 . 89 g of oily desired compound ( yield : 88 %). 1 h - nmr ( cdcl 3 , 200 mhz ) δ 0 . 08 ( s , 6h ), 0 . 86 ( s , 9h ), 1 . 24 ( d , j = 4 . 0 hz , 3h ), 1 . 27 ( d , j = 3 . 0 hz , 3h ), 1 . 62 - 2 . 24 ( m , 10h ), 3 . 01 ( dd , j = 7 . 6 , 2 . 0 hz , 1h ), 3 . 43 - 3 . 58 ( m , 1h ), 3 . 63 ( s , 3h ), 3 . 88 - 4 . 01 ( m , 2h ), 5 . 21 - 5 . 39 ( m , 2h ), 580 - 6 . 01 ( m , 1h ), 7 . 19 - 7 . 39 ( m , 5h ); ir ( chcl 3 ) 1377 , 1447 , 1680 , 1678 , 1745 , 2252 , 2948 cm − 1 . preparation of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 1 -( 4 - methoxybenzyloxycarbonylmethyl )- 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester ( the general formula ( xi ) compound ) the reaction was performed in the same manner as example 18 except for using 3 . 0 g of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester and 4 - methoxybenzylbromoacetate instead of allyibromoacetate , thus obtaining 3 . 23 g of oily desired compound ( yield : 83 %). 1 h - nmr ( cdcl 3 , 200 mhz ) δ 0 . 06 ( s , 6h ), 0 . 86 ( s , 9h ), 1 . 23 ( d , j = 5 . 2 hz , 3h ), 1 . 27 ( d , j = 6 . 2 hz , 3h ), 1 . 48 - 1 . 68 ( m , 5h ), 2 . 04 - 2 . 21 ( m , 5h ), 3 . 02 ( dd , j = 7 . 4 , 2 . 1 hz , 1h ), 3 . 52 - 3 . 59 ( m , 1h ), 3 . 63 ( s , 3h ), 3 . 81 ( s , 3h ), 4 . 17 ( dd , j = 62 . 4 , 18 hz , 2h ), 4 . 05 - 4 . 17 ( m , 2h ), 5 . 07 ( s , 2h ), 6 . 91 ( m , 2h ), 7 . 20 - 7 . 41 ( m , 7h ). preparation of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 1 -( 4 - nitrobenzyloxycarbonylmethyl )- 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2carboxylic acid ester ( the general formula ( xi ) compound ) the reaction was performed in the same manner as example 18 except for using [ 4 - nitrobenzylbromoacetate was employed instead of ] 600 mg of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 3 -[( 1r )- 1 - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester and 4 - nitrobenzybromoacetate instead of allyibromoacetate , thus obtaining 646 mg of oily desired compound ( yield : 84 %). 1 h - nmr ( cdcl 3 , 200 mhz ) δ 0 . 02 ( s , 6h ), 0 . 82 ( s , 9h ), 1 . 23 ( d , j = 6 . 8 hz , 3h ), 1 . 25 ( d , j = 6 . 8 hz , 3h ), 1 . 56 - 1 . 78 ( m , 6h ), 2 . 01 - 2 . 36 ( m , 4h ), 3 . 03 ( dd , j = 7 . 3 , 2 . 2 , 1h ), 2 . 04 - 2 . 21 ( m , 5h ), 3 . 02 ( dd , j = 7 . 4 , 2 . 1 hz , 1h ), 3 . 52 - 3 . 59 ( m , 1h ), 3 . 60 ( s , 3h ), 4 . 17 ( dd , j = 62 . 4 , 18 hz , 2h ), 5 . 20 ( s , 2h ), 6 . 91 ( m , 2h ), 7 . 18 ‘ 7 . 37 ( m , 5h ), 7 . 45 ( d , j = 8 . 6 hz , 2h ), 8 . 21 ( d , j = 8 . 6 hz , 2h ). preparation of allyl ( 1r , 5r , 6s )- 6 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 1 - methyl - 2 - diphenylphophoryloxy - 2 - carbapen - 2 - em - 3 - carboxylic acid ester ( the general formula ( v ) compound ) 4 . 89 g of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 1 - allyloxycarbonylmethyl - 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester was dissolved in 60 ml of anhydrous tetrahydrofuran and cooled down to − 45 ° c . under the atomosphere of nitrogen gas , 16 . 9 ml of sodium bis ( trimethylsilyl ) amide ( 1 mol of tetrahydrofuran solution ) was slowly added to the mixture . with the temperature at − 30 ° c ., 1 . 2 ml of chlorotrimethylsilane was added to the reacting mixture and stirred at the same temperature for 5 minutes . with the slow addition of 2 . 23 ml of diphenylchlorophosphate , 44 mg of 4 - dimethylaminopyridine was further added to the reacting solution and stirred at the temperature of − 30 ˜− 10 ° c . for 2 hours . with the addition of phosphate buffer solution ( ph = 7 . 0 ), the solution was extracted with ethyl acetate two times , dried over mgso 4 and concentrated under reduced pressure . 50 ml of a mixed solution ( ethyl acetate : hexane = 1 : 4 ) was added to the residue and crystallized . after being filtered off , methyl 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester in yellow crystal was obtained . this compound , a stereoselective additive , was prepared in the same manner as preparation example 2 and its recycling can be possible . the remaining solution , so concentrated , was purified on silica gel column chromatography ( elute : ethyl acetate : hexane = 1 : 4 ) to obtain 4 . 01 g of pure oily desired compound ( yield : 91 %). 1 h - nmr ( cdcl 3 , 200 mhz ) δ 0 . 06 ( s , 6h ), 0 . 87 ( s , 9h ), 1 . 16 ( d , j = 7 . 4 hz , 3h ), 1 . 21 ( d , j = 6 . 0 hz , 3h ), 3 . 22 ( dd , j = 6 . 4 , 2 . 8 hz , 1h ), 3 . 31 - 3 . 52 ( m , 1h ), 4 . 07 - 4 . 21 ( m , 2h ), 4 . 64 ( d , j = 5 . 8 hz , 2h ), 5 . 16 ( dd , j = 10 . 6 , 1 . 6 hz , 1h ), 5 . 32 ( dd , j = 17 . 4 , 1 . 6 hz , 1h ), 5 . 75 - 5 . 94 ( m , 1h ), 7 . 17 - 7 . 44 ( m , 10h ). preparation of 4 - nitrobenzyl ( 1r , 5r , 6s )- 6 -[( 1r )- 1 - t - butyidimethylsilyloxyethyl ]- 1 - methyl - 2 - diphenylphosphoryloxy - 2 - carbapen - 2 - em - 3 - carboxylic acid ester ( the general formula ( v ) compound ) the reaction was performed in the same manner as example 21 using 300 mg of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 1 -( 4 - nitrobenzyloxycarbonylmethyl )- 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2en - 2 - carboxylic acid ester as starting material , thus obtaining 87 mg of oily desired compound ( yield : 32 %). 1 h - nmr ( cdcl 3 , 200 mhz ) δ 0 . 06 ( s , 6h ), 0 . 85 ( s , 9h ), 1 . 22 ( d , j = 5 . 2 hz , 3h ), 1 . 28 ( d , j = 6 . 2 hz , 3h ), 3 . 23 - 3 . 33 ( m , 1h ), 3 . 36 - 3 . 48 ( m , 2h ), 5 . 21 - 5 . 39 ( q , j = 10 hz , 2h ), 7 . 12 - 7 . 42 ( m , 10h ), 7 . 53 ( d , j = 8 . 6 hz , 2h ), 8 . 11 ( d , j = 8 . 4 hz , 2h ). preparation of 4 - methoxybenzyl ( 1r , 5r , 6s )- 6 -[( 1r )- 1 - t - butyidimethylsilyloxyethyl ]- 1 - methyl - 2 - diphenylphosphoryloxy - 2 - carbapen - 2 - em - 3 - carboxylic acid ester ( the general formula ( v ) compound ) the reaction was performed in the same manner as example 21 using 323 mg of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 1 -( 4 - methoxybenzyloxycarbonylmethyl )- 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2en - 2 - carboxylic acid ester as starting material , thus obtaining 222 mg of oily desired compound ( yield : 85 %). 1 h - nmr ( cdcl 3 , 200 mhz ) δ 0 . 01 ( s , 6h ), 0 . 82 ( s , 9h ), 1 . 12 ( d , j = 7 . 4 hz , 3h ), 1 . 17 ( d , j = 6 . 0 hz , 3h ), 3 . 24 - 3 . 49 ( m , 1h ), 3 . 72 ( s , 3h ), 4 . 01 - 4 . 22 ( m , 2h ), 7 . 08 - 7 . 41 ( m , 12h ). 388 mg of methyl 5 -{( 2r )- 2 -[( 3s , 4r )- 3 -[( 1r )- 1 - t - butyldimethylsilyloxyethyl ]- 2 - oxo - azetidine - 4 - yl ] propionyl }- 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester , so prepared by example 10 , was dissolved in 10 ml of anhydrous tetrahydrofuran and 0 . 34 ml of water and cooled down to 0 ° c . 0 . 6 ml of 30 % hydrogen peroxide and 56 mg of lithium hydroxide were added to the reacting solution . the solution was stirred at the same temperature for 1 hour and then , 4 ml of 1 . 5 normal sodium sulfite solution was added to the reacting solution . after tetrahydrofuran was concentrated under reduced pressure , the crystals formed from the remaining solution was being filtered off to obtain methyl 4 - oxo - 3 - phenyl - 1 - oxa - 5 - azaspiro [ 5 . 5 ] undec - 2 - en - 2 - carboxylic acid ester . after the remaining solution was washed with chloroform and ph was also adjusted to about 1 using 10 % hydrochloric acid , the solution was extracted with ethyl acetate , dried over mgso 4 and concentrated under reduced pressure . the residue was crystallized with ethyl acetate and hexane to obtain 144 mg of desired compound in white solid form ( yield : 73 %). ml 143 - 1460 ° c . through the preparation of the general formula ( i ) compound using the general formula ( iii ) compound as an stereoselective additive of this invention , the stereoisomers only having β - methyl group in 1 ′- position of the general formula ( i ) compound may be made available in an effective manner . the existing literature ( tetrahedron , vol . 52 , no . 2 pp . 331 - 375 . 1996 ) has disclosed a process of preparing the intermediate of β - methylcarbapenem antibiotics corresponding to the general formula ( i ) of this invention using a stereoselective additive . the following table 4 summarized the ratios of β - isomer generated , when zinc powder was used as an easily handled reagent . further , this invention has an advantage of recycling the by - product of the general formula ( iii ) compound , a stereoselective additive , after recovery process during the process of preparing the general formula ( v ) compound , a final intermediate of carbapenem antibiotic from the general formula ( i ) compound .