<title>Background</title> <p>Compounds with a monofluoromethyl moiety are of great importance with regards to isostere-based drug design [##UREF##0##1##–##UREF##3##4##]. Consequently, synthesis of new functionalized α-monofluorine-substituted active methylene derivatives has attracted considerable attention particularly in the field of medicinal chemistry [##UREF##4##5##–##UREF##5##6##]. One of the major interests in our group has focused on developing new fluorination reagents or fluorinated building blocks for preparation of fluorine-substituted compounds [##REF##12762751##7##–##REF##17444648##13##]. As part of our ongoing effort to extend the applications of fluorine-containing (phenylsulfonyl)methane derivatives, we envisaged that fluoro(phenylsulfonyl)methane, α-substituted by nitro, cyano, ester, or acetyl would be useful for the synthesis of functionalized monofluoromethylated compounds, which would undergo various transformations. New synthetic methods for the synthesis of α-substituted fluoro(phenylsulfonyl)methane derivatives under mild reaction conditions, using convenient starting materials, are still desirable.</p> <p>Fluorinated carbanions are in principle "hard" nucleophiles that readily undergo 1,2-addition with Michael type acceptors instead of 1,4-addition [##UREF##9##14##–##UREF##10##16##]. Different strategies have been employed to achieve 1,4-addition, which is still percieved to be a challenge. For instance, Yamamoto [##UREF##11##17##] and Röschenthaler [##UREF##12##18##–##REF##14510551##19##] have made use of bulky aluminum Lewis acids to protect the carbonyl of Michael acceptors and thus sucessfully transferred the trifluoromethyl anion generated from the "Ruppert-Prakash reagent" (TMS-CF<sub>3</sub>) in a 1,4-manner rather than the favored 1,2-addition. Portella et al. [##UREF##13##20##] have shown that 1,4-addition of difluoroenoxysilanes to enones can be used to introduce difluoromethylene moiety while Kumadaki and coworkers [##UREF##14##21##–##UREF##15##22##] have used bromodifluoroacetate with a copper catalyst to introduce the CF<sub>2</sub> functionality. There also exist few reports on the 1,4-addition of monofluoromethylene moieties to α,β-unsaturated compounds [##UREF##16##23##–##UREF##17##24##]. Takeuchi and coworkers [##UREF##18##25##] have shown that α-fluoronitroalkanes can undergo 1,4-addition to methyl vinyl ketone and acrylonitrile to afford the dialkylated products.</p>
<title>Results and Discussion</title> <p>Herein, we disclose the facile reaction of fluoro(phenylsulfonyl)methane derivatives and various Michael acceptors. We first began with the preparation of nitro, cyano, ester, or acetyl-substituted (phenylsulfonyl)methanes from the corresponding (phenylthio)methane derivatives, the precursors of α-substituted fluoro(phenylsulfonyl)methane derivatives. Oxidation of (nitromethyl)(phenyl)sulfide with aqueous hydrogen peroxide [H<sub>2</sub>O<sub>2</sub>, 30% (wt)] was attempted in acetic acid at room temperature. Tuning the conditions by using 4-fold excess of H<sub>2</sub>O<sub>2 </sub>afforded 90% yield of (nitromethylsulfonyl)benzene overnight (##TAB##0##Table 1##, entry 1) [##UREF##19##26##–##UREF##21##28##]. <bold>2a</bold>–<bold>c</bold> and <bold>2e</bold> were prepared in 76–91% yields under the optimized condition and used without further purification [##UREF##23##30##–##UREF##27##34##]. Interestingly, the oxidation of <bold>1d</bold> gave a mixture of <bold>2d</bold> and methylsulfonylbenzene in a ratio of 2:1. Hence, compound <bold>2d</bold> was synthesized from another known procedure [##UREF##22##29##]. Fluorobis(phenylsulfonyl)methane <bold>3f</bold> was prepared following a literature procedure by fluorinating bis(phenylsulfonyl)methane, which is commercially available [##UREF##8##11##].</p> <p>Our strategy for the preparation of monofluoro methanes was to use commercially available Selectfluor<sup>®</sup> [##UREF##28##35##] as the electrophilic fluorine source. The monofluorination of (nitromethylsulfonyl)benzene with Selectfluor<sup>®</sup> under the improved conditions [##UREF##29##36##] [treatment of (nitromethylsulfonyl)benzene (6.75 mmol) with NaH (6.75 mmol) in THF (25 mL) followed by Selectfluor<sup>®</sup> (6.75 mmol) in 15 mL of DMF at 0 °C] gave [fluoro(nitro)methylsulfonyl]benzene <bold>3a</bold> in 62% isolated yield (##TAB##0##Table 1##, entry 1). A doublet was observed at δ −142.16 ppm in the <sup>19</sup>F NMR spectrum of <bold>3a</bold>, which matched our previously reported result [##UREF##8##11##]. Other fluoro(phenylsulfonyl)methane derivatives were synthesized in 45–61% yields under similar conditions (##TAB##0##Table 1##, entries 2–5).</p> <p>Alkylation of <bold>3a</bold>–<bold>d</bold>, <bold>3f</bold> is reported to be a challenge because the combined carbanion-stabilizing abilities of the two strong electron-withdrawing groups are not sufficient to overcome the well-known carbanion destabilization by the adjacent fluorine [##UREF##18##25##]. With this in mind, we first opted to use phosphines as nucleophilic catalysts. Concerning applications of <bold>3a</bold>–<bold>d</bold>, and <bold>3f</bold> in constructing the carbon-carbon bond, a reaction of [fluoro(nitro)methylsulfonyl]benzene with methyl vinyl ketone was first tested in the presence of PPh<sub>3</sub> (50 mol%) in THF at room temperature under argon. Interestingly, 5-fluoro-5-nitro-5-(phenylsulfonyl)pentan-2-one (<bold>5a</bold>) was obtained in 93% yield as the sole product, which was characterized by <sup>1</sup>H, <sup>13</sup>C, <sup>19</sup>F NMR, and HRMS. In the <sup>19</sup>F NMR spectrum of <bold>5a</bold>, two doublets at δ −125.94 ppm were observed. As it is known, fluoro substitution can cause problems in transformations, since fluoride can also act as a leaving group. Notably, fluorine-free products were not detected in the course of above-mentioned Michael reactions, under the reaction conditions.</p> <p>We then screened various electronically and sterically different phosphines such as PPh<sub>3</sub>, Bu<sub>3</sub>P, (<italic>i</italic>Pr)<sub>3</sub>P and PMe<sub>3</sub>. Initial experiments revealed that the catalytic activity of phosphines and phosphine loading (varying from 20% to 50%) efficiently promoted the Michael reaction. With 50 mol% catalyst loading, the reaction rates were approximately 2- to 3-fold faster than the corresponding 20 mol% PPh<sub>3</sub> catalyzed reactions. A dramatic increase in the efficiency of the reaction came from the usage of less bulkier phosphine, PMe<sub>3</sub> (20 mol%), which led to the best result (##TAB##1##Table 2##, entry 1).</p> <p>Having established optimal conditions, we then investigated the scope of various substrates in the reaction (##TAB##1##Table 2##). Methyl vinyl ketone reacted with <bold>3a</bold>, <bold>3b</bold>, <bold>3c</bold>, or <bold>3f</bold> to furnish the corresponding products in good to excellent yields, respectively, except in the case of 1-fluoro-1-(phenylsulfonyl)propane-2-one (<bold>3d</bold>) (##TAB##1##Table 2##, entries 1–4). Compound <bold>3d</bold> gave complex results due to the reactions of the two types of active acidic α-Hs adjacent to the carbonyl group in the molecule.</p> <p>When ethyl acrylate was subjected to similar reaction conditions, the yields of the products were 60–88% after prolonged reaction time. Compared to methyl vinyl ketone, the reaction rates were slow due to the somewhat lower reactivity of ethyl acrylate (##TAB##1##Table 2##, entries 5–8). All products obtained were characterised by <sup>19</sup>F, <sup>1</sup>H, <sup>13</sup>C NMR spectra, as well as HRMS. In addition, base-sensitive functional groups such as cyano, nitro, and ester were well tolerated during the course of the reaction. The failure of (<italic>E</italic>)-pent-3-en-2-one to undergo the Michael reaction under these conditions demonstrates that the reaction is not tolerant of substituents at the terminal position of the double bond due to steric effects.</p> <p>On the basis of the above mentioned results, a proposed mechanism for the formation of <bold>5a</bold>–<bold>h</bold> is outlined in ##FIG##0##Scheme 1##. Trialkylphosphine catalysed Morita-Baylis-Hillman reaction is well studied by a number of groups [##UREF##30##37##–##UREF##32##39##]. Addition of PMe<sub>3</sub> to alkene <bold>4</bold> generates the dipolar intermediate. The latter abstracts a proton from the α-fluoro-substituted methylene derivative <bold>3</bold>, followed by an intermolecular S<sub>N</sub>2 reaction to furnish the desired product <bold>5</bold> and the release of PMe<sub>3</sub> (##FIG##0##Scheme 1##). The mechanism supports the fact that the less steric hindered catalyst PMe<sub>3</sub> is more efficient than PPh<sub>3</sub>, Bu<sub>3</sub>P or (<italic>i</italic>Pr)<sub>3</sub>P.</p> <p>In addition, the presence of electron withdrawing groups such as the phenylsulfonyl group can be exploited to generate a carbanion that can act as a "soft" nucleophile [##REF##16930033##40##–##REF##17708659##41##]. The phenylsulfonyl group delocalises the electron density on the fluorinated carbanion center, which makes the resulting nucleophile softer and more suitable for 1,4-addition with Michael acceptors. Hence, we explored the possibility of a base induced Michael addition reaction. Among the various bases and solvent combinations that we explored, the K<sub>2</sub>CO<sub>3</sub>/DMF system was found to be very efficient both in terms of conversions as well as reaction times.</p> <p>The reactions were carried out at room temperature and the completion observed within 2 h. The reaction was found to be versatile for various α,β-unsaturated compounds such as ketones, esters, nitriles and sulfones (##TAB##2##Table 3##). In case of α,β-unsaturated aldehydes the reaction was found to be not clean and too many fluorine peaks appeared in the <sup>19</sup>F NMR even when the reaction was carried out at low temperatures. On the other hand, α,β-unsaturated nitriles underwent a second Michael addition of the product <bold>6h</bold>. Both fluoro(bisphenylsulfonyl)methane and fluoronitro(phenylsulfonyl)methane were added to propynoates under similar conditions. As expected, a mixture of both <italic>cis</italic> and <italic>trans</italic> products were obtained as shown in ##TAB##2##Table 3## (entries 10–11). Interestingly, in the case of fluoronitro(phenylsulfonyl)methane only the <italic>trans</italic> isomer <bold>6l</bold> was obtained in an appreciable amount while the <italic>cis</italic> product was observed only in traces.</p> <p>During our study, we observed that the steric factor affects the addition of the pronucleophile to the Michael acceptor. Substitution at the α-position of the Michael acceptor affects the reactivity of the nucleophile generated by the K<sub>2</sub>CO<sub>3</sub>/DMF system. The reaction of fluoro(bisphenylsulfonyl)methane with methyl crotonate was found to give only 50% conversion based on <sup>19</sup>F NMR after 36 h and methyl cinnamate did not react at all at room temperature using the K<sub>2</sub>CO<sub>3</sub>/DMF system. These observations are consistent with what was observed in the phosphine case discussed earlier. Attempted reductive desulfonylation on compound <bold>6d</bold> using Mg/CH<sub>3</sub>OH [##UREF##8##11##] was not selective as simultaneous reduction of the carbonyl group was also observed.</p>
<title>Results and Discussion</title> <p>Herein, we disclose the facile reaction of fluoro(phenylsulfonyl)methane derivatives and various Michael acceptors. We first began with the preparation of nitro, cyano, ester, or acetyl-substituted (phenylsulfonyl)methanes from the corresponding (phenylthio)methane derivatives, the precursors of α-substituted fluoro(phenylsulfonyl)methane derivatives. Oxidation of (nitromethyl)(phenyl)sulfide with aqueous hydrogen peroxide [H<sub>2</sub>O<sub>2</sub>, 30% (wt)] was attempted in acetic acid at room temperature. Tuning the conditions by using 4-fold excess of H<sub>2</sub>O<sub>2 </sub>afforded 90% yield of (nitromethylsulfonyl)benzene overnight (##TAB##0##Table 1##, entry 1) [##UREF##19##26##–##UREF##21##28##]. <bold>2a</bold>–<bold>c</bold> and <bold>2e</bold> were prepared in 76–91% yields under the optimized condition and used without further purification [##UREF##23##30##–##UREF##27##34##]. Interestingly, the oxidation of <bold>1d</bold> gave a mixture of <bold>2d</bold> and methylsulfonylbenzene in a ratio of 2:1. Hence, compound <bold>2d</bold> was synthesized from another known procedure [##UREF##22##29##]. Fluorobis(phenylsulfonyl)methane <bold>3f</bold> was prepared following a literature procedure by fluorinating bis(phenylsulfonyl)methane, which is commercially available [##UREF##8##11##].</p> <p>Our strategy for the preparation of monofluoro methanes was to use commercially available Selectfluor<sup>®</sup> [##UREF##28##35##] as the electrophilic fluorine source. The monofluorination of (nitromethylsulfonyl)benzene with Selectfluor<sup>®</sup> under the improved conditions [##UREF##29##36##] [treatment of (nitromethylsulfonyl)benzene (6.75 mmol) with NaH (6.75 mmol) in THF (25 mL) followed by Selectfluor<sup>®</sup> (6.75 mmol) in 15 mL of DMF at 0 °C] gave [fluoro(nitro)methylsulfonyl]benzene <bold>3a</bold> in 62% isolated yield (##TAB##0##Table 1##, entry 1). A doublet was observed at δ −142.16 ppm in the <sup>19</sup>F NMR spectrum of <bold>3a</bold>, which matched our previously reported result [##UREF##8##11##]. Other fluoro(phenylsulfonyl)methane derivatives were synthesized in 45–61% yields under similar conditions (##TAB##0##Table 1##, entries 2–5).</p> <p>Alkylation of <bold>3a</bold>–<bold>d</bold>, <bold>3f</bold> is reported to be a challenge because the combined carbanion-stabilizing abilities of the two strong electron-withdrawing groups are not sufficient to overcome the well-known carbanion destabilization by the adjacent fluorine [##UREF##18##25##]. With this in mind, we first opted to use phosphines as nucleophilic catalysts. Concerning applications of <bold>3a</bold>–<bold>d</bold>, and <bold>3f</bold> in constructing the carbon-carbon bond, a reaction of [fluoro(nitro)methylsulfonyl]benzene with methyl vinyl ketone was first tested in the presence of PPh<sub>3</sub> (50 mol%) in THF at room temperature under argon. Interestingly, 5-fluoro-5-nitro-5-(phenylsulfonyl)pentan-2-one (<bold>5a</bold>) was obtained in 93% yield as the sole product, which was characterized by <sup>1</sup>H, <sup>13</sup>C, <sup>19</sup>F NMR, and HRMS. In the <sup>19</sup>F NMR spectrum of <bold>5a</bold>, two doublets at δ −125.94 ppm were observed. As it is known, fluoro substitution can cause problems in transformations, since fluoride can also act as a leaving group. Notably, fluorine-free products were not detected in the course of above-mentioned Michael reactions, under the reaction conditions.</p> <p>We then screened various electronically and sterically different phosphines such as PPh<sub>3</sub>, Bu<sub>3</sub>P, (<italic>i</italic>Pr)<sub>3</sub>P and PMe<sub>3</sub>. Initial experiments revealed that the catalytic activity of phosphines and phosphine loading (varying from 20% to 50%) efficiently promoted the Michael reaction. With 50 mol% catalyst loading, the reaction rates were approximately 2- to 3-fold faster than the corresponding 20 mol% PPh<sub>3</sub> catalyzed reactions. A dramatic increase in the efficiency of the reaction came from the usage of less bulkier phosphine, PMe<sub>3</sub> (20 mol%), which led to the best result (##TAB##1##Table 2##, entry 1).</p> <p>Having established optimal conditions, we then investigated the scope of various substrates in the reaction (##TAB##1##Table 2##). Methyl vinyl ketone reacted with <bold>3a</bold>, <bold>3b</bold>, <bold>3c</bold>, or <bold>3f</bold> to furnish the corresponding products in good to excellent yields, respectively, except in the case of 1-fluoro-1-(phenylsulfonyl)propane-2-one (<bold>3d</bold>) (##TAB##1##Table 2##, entries 1–4). Compound <bold>3d</bold> gave complex results due to the reactions of the two types of active acidic α-Hs adjacent to the carbonyl group in the molecule.</p> <p>When ethyl acrylate was subjected to similar reaction conditions, the yields of the products were 60–88% after prolonged reaction time. Compared to methyl vinyl ketone, the reaction rates were slow due to the somewhat lower reactivity of ethyl acrylate (##TAB##1##Table 2##, entries 5–8). All products obtained were characterised by <sup>19</sup>F, <sup>1</sup>H, <sup>13</sup>C NMR spectra, as well as HRMS. In addition, base-sensitive functional groups such as cyano, nitro, and ester were well tolerated during the course of the reaction. The failure of (<italic>E</italic>)-pent-3-en-2-one to undergo the Michael reaction under these conditions demonstrates that the reaction is not tolerant of substituents at the terminal position of the double bond due to steric effects.</p> <p>On the basis of the above mentioned results, a proposed mechanism for the formation of <bold>5a</bold>–<bold>h</bold> is outlined in ##FIG##0##Scheme 1##. Trialkylphosphine catalysed Morita-Baylis-Hillman reaction is well studied by a number of groups [##UREF##30##37##–##UREF##32##39##]. Addition of PMe<sub>3</sub> to alkene <bold>4</bold> generates the dipolar intermediate. The latter abstracts a proton from the α-fluoro-substituted methylene derivative <bold>3</bold>, followed by an intermolecular S<sub>N</sub>2 reaction to furnish the desired product <bold>5</bold> and the release of PMe<sub>3</sub> (##FIG##0##Scheme 1##). The mechanism supports the fact that the less steric hindered catalyst PMe<sub>3</sub> is more efficient than PPh<sub>3</sub>, Bu<sub>3</sub>P or (<italic>i</italic>Pr)<sub>3</sub>P.</p> <p>In addition, the presence of electron withdrawing groups such as the phenylsulfonyl group can be exploited to generate a carbanion that can act as a "soft" nucleophile [##REF##16930033##40##–##REF##17708659##41##]. The phenylsulfonyl group delocalises the electron density on the fluorinated carbanion center, which makes the resulting nucleophile softer and more suitable for 1,4-addition with Michael acceptors. Hence, we explored the possibility of a base induced Michael addition reaction. Among the various bases and solvent combinations that we explored, the K<sub>2</sub>CO<sub>3</sub>/DMF system was found to be very efficient both in terms of conversions as well as reaction times.</p> <p>The reactions were carried out at room temperature and the completion observed within 2 h. The reaction was found to be versatile for various α,β-unsaturated compounds such as ketones, esters, nitriles and sulfones (##TAB##2##Table 3##). In case of α,β-unsaturated aldehydes the reaction was found to be not clean and too many fluorine peaks appeared in the <sup>19</sup>F NMR even when the reaction was carried out at low temperatures. On the other hand, α,β-unsaturated nitriles underwent a second Michael addition of the product <bold>6h</bold>. Both fluoro(bisphenylsulfonyl)methane and fluoronitro(phenylsulfonyl)methane were added to propynoates under similar conditions. As expected, a mixture of both <italic>cis</italic> and <italic>trans</italic> products were obtained as shown in ##TAB##2##Table 3## (entries 10–11). Interestingly, in the case of fluoronitro(phenylsulfonyl)methane only the <italic>trans</italic> isomer <bold>6l</bold> was obtained in an appreciable amount while the <italic>cis</italic> product was observed only in traces.</p> <p>During our study, we observed that the steric factor affects the addition of the pronucleophile to the Michael acceptor. Substitution at the α-position of the Michael acceptor affects the reactivity of the nucleophile generated by the K<sub>2</sub>CO<sub>3</sub>/DMF system. The reaction of fluoro(bisphenylsulfonyl)methane with methyl crotonate was found to give only 50% conversion based on <sup>19</sup>F NMR after 36 h and methyl cinnamate did not react at all at room temperature using the K<sub>2</sub>CO<sub>3</sub>/DMF system. These observations are consistent with what was observed in the phosphine case discussed earlier. Attempted reductive desulfonylation on compound <bold>6d</bold> using Mg/CH<sub>3</sub>OH [##UREF##8##11##] was not selective as simultaneous reduction of the carbonyl group was also observed.</p>
<title>Conclusion</title> <p>In summary, a convenient protocol for the preparation of α-substituted fluoro(phenylsulfonyl)methane derivatives has been described and its subsequent use in 1,4-addition to a variety of Michael acceptors has also been demonstrated. Further applications of fluoro(phenylsulfonyl)methane including stereocontrolled synthesis will be reported in due course.</p>
<p>The 1,4-addition of a monofluoromethyl nucleophile to a variety of α,β-unsaturated compounds has been achieved under mild conditions using either phosphines or potassium carbonate at room temperature. α-Substituted fluoro(phenylsulfonyl)methane easily undergoes Michael addition to α,β-unsaturated ketones, esters, nitriles, sulfones, as well as propynoates at room temperature to yield the corresponding adducts in moderate to excellent yields.</p>
<title>Supporting Information</title>
<p>Support of our work by the Loker Hydrocarbon Research Institute is gratefully acknowledged.</p>
<fig id="C1" position="float"><label>Scheme 1</label><caption><p>Reaction mechanism for phosphine catalyzed 1,4-addition to α,β-unsaturated compounds.</p></caption></fig>
<table-wrap id="T1" position="float"><label>Table 1</label><caption><p>Oxidation of sulfides and monofluorination of sulfones.</p></caption><table frame="hsides" rules="groups"><tr><td align="center" colspan="6" valign="middle" rowspan="1"></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">Entry</td><td align="center" valign="middle" rowspan="1" colspan="1">R</td><td align="center" valign="middle" rowspan="1" colspan="1"><bold>2</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">Yield<sup>a</sup> (%)</td><td align="center" valign="middle" rowspan="1" colspan="1"><bold>3</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">Yield<sup>a</sup> (%)</td></tr><tr><td align="left" colspan="6" valign="middle" rowspan="1"><hr/></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">1</td><td align="center" valign="middle" rowspan="1" colspan="1">NO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>2a</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">90</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>3a</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">62</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">2</td><td align="center" valign="middle" rowspan="1" colspan="1">CN</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>2b</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">76</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>3b</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">45</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">3</td><td align="center" valign="middle" rowspan="1" colspan="1">CO<sub>2</sub>Et</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>2c</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">83</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>3c</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">56</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">4</td><td align="center" valign="middle" rowspan="1" colspan="1">COMe</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>2d</bold></td><td align="center" valign="middle" rowspan="1" colspan="1"><sup>b</sup></td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>3d</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">61</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">5</td><td align="center" valign="middle" rowspan="1" colspan="1">CH=CH<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>2e</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">91</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>3e</bold></td><td align="center" valign="middle" rowspan="1" colspan="1"><sup>c</sup></td></tr></table></table-wrap> <table-wrap id="T2" position="float"><label>Table 2</label><caption><p>PMe<sub>3</sub>-catalyzed reaction of fluoro(phenylsulfonyl)-substituted methane derivatives with methyl vinyl ketone and ethyl acrylate.</p></caption><table frame="hsides" rules="groups"><tr><td align="center" colspan="6" valign="middle" rowspan="1"></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">Entry</td><td align="center" valign="middle" rowspan="1" colspan="1">R<sub>1</sub></td><td align="center" valign="middle" rowspan="1" colspan="1">R<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1">Product</td><td align="center" valign="middle" rowspan="1" colspan="1">Time (h)</td><td align="center" valign="middle" rowspan="1" colspan="1">Yield<sup>a</sup> (%)</td></tr><tr><td align="left" colspan="6" valign="middle" rowspan="1"><hr/></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">1</td><td align="center" valign="middle" rowspan="1" colspan="1">NO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1">Me</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5a</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">40</td><td align="center" valign="middle" rowspan="1" colspan="1">93</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">2</td><td align="center" valign="middle" rowspan="1" colspan="1">CN</td><td align="center" valign="middle" rowspan="1" colspan="1">Me</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5b</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">22</td><td align="center" valign="middle" rowspan="1" colspan="1">90</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">3</td><td align="center" valign="middle" rowspan="1" colspan="1">CO<sub>2</sub>Et</td><td align="center" valign="middle" rowspan="1" colspan="1">Me</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5c</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">24</td><td align="center" valign="middle" rowspan="1" colspan="1">75</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">4</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1">Me</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5d</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">17</td><td align="center" valign="middle" rowspan="1" colspan="1">91</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">5</td><td align="center" valign="middle" rowspan="1" colspan="1">NO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1">OEt</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5e</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">72</td><td align="center" valign="middle" rowspan="1" colspan="1">64</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">6</td><td align="center" valign="middle" rowspan="1" colspan="1">CN</td><td align="center" valign="middle" rowspan="1" colspan="1">OEt</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5f</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">72</td><td align="center" valign="middle" rowspan="1" colspan="1">60</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">7</td><td align="center" valign="middle" rowspan="1" colspan="1">CO<sub>2</sub>Et</td><td align="center" valign="middle" rowspan="1" colspan="1">OEt</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5g</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">116</td><td align="center" valign="middle" rowspan="1" colspan="1">71</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">8</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1">OEt</td><td align="center" valign="middle" rowspan="1" colspan="1"><break/><bold>5h</bold></td><td align="center" valign="middle" rowspan="1" colspan="1">67</td><td align="center" valign="middle" rowspan="1" colspan="1">88</td></tr></table></table-wrap> <table-wrap id="T3" position="float"><label>Table 3</label><caption><p>K<sub>2</sub>CO<sub>3</sub>/DMF catalyzed 1,4-addition to α,β-unsaturated esters, ketones, sulfone, nitriles and propynoates.</p></caption><table frame="hsides" rules="groups"><tr><td align="center" colspan="5" valign="middle" rowspan="1"></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">Entry</td><td align="center" valign="middle" rowspan="1" colspan="1">R</td><td align="center" valign="middle" rowspan="1" colspan="1">Substrate</td><td align="center" valign="middle" rowspan="1" colspan="1">Product (<bold>5</bold>/<bold>6</bold>)</td><td align="center" valign="middle" rowspan="1" colspan="1">Yield<sup>a</sup></td></tr><tr><td align="left" colspan="5" valign="middle" rowspan="1"><hr/></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">1</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">70</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">2</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">70</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">3</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">71</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">4</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">90</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">5</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">79</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">6</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">60</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">7</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">54 (1:2)</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">8</td><td align="center" valign="middle" rowspan="1" colspan="1">NO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">45</td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">9</td><td align="center" valign="middle" rowspan="1" colspan="1">COOEt</td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">65<sup>b</sup></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">10</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">76 (2:3)<sup>c</sup></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">11</td><td align="center" valign="middle" rowspan="1" colspan="1">PhSO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">60 (1:1)<sup>c</sup></td></tr><tr><td align="center" valign="middle" rowspan="1" colspan="1">12</td><td align="center" valign="middle" rowspan="1" colspan="1">NO<sub>2</sub></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1"></td><td align="center" valign="middle" rowspan="1" colspan="1">46<sup>d</sup></td></tr></table></table-wrap>
<supplementary-material content-type="local-data" id="SD1"><label>File 1</label><caption><p>Experimental procedures, full spectroscopic data and spectra.</p></caption></supplementary-material> <supplementary-material content-type="local-data" id="SD2"><label>File 2</label><caption><p>Spectra.</p></caption></supplementary-material>
<table-wrap-foot><fn id="TFN1"><p><sup>a</sup>isolated yield, <sup>b</sup><bold>2d</bold> was prepared according to ref. [##UREF##22##29##], <sup>c</sup>no product obtained</p></fn></table-wrap-foot> <table-wrap-foot><fn id="TFN2"><p><sup>a</sup>isolated yield</p></fn></table-wrap-foot> <table-wrap-foot><fn id="TFN3"><p><sup>a</sup>isolated yield, <sup>b</sup>NMR yield (based on <sup>19</sup>F NMR), <sup>c</sup><italic>cis : trans</italic> ratio, <sup>d</sup>only trace amount of <italic>cis</italic> isomer observed</p></fn></table-wrap-foot>
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Beilstein J Org Chem. 2008 May 21; 4:17