A General Method for the Synthesis of Both Enantiomers of Optically Pure β-Hydroxy Esters from (S)-(p-Chlorophenylsulfinyl)acetone Easily Obtainable by Kinetic Resolution with Bakers’ Yeast

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Abstract
Both enantiomers of various optically pure (R)- and (S)-β-hydroxy esters were generally synthesized from (S)-(p-chlorophenylsulfinyl)acetone obtained by kinetic resolution with bakers’ yeast, followed by γ-alkylation, diastereoselective reduction, subsequent introduction of ester group and reductive elimination of the sulfinyl group. The key step of the diastereoselective reduction of (S)-β-keto sulfoxides was performed with diisobutylaluminum hydride to give (R)c-(S)s-β-hydroxy sulfoxides or after complexation with zinc chloride followed by addition of diisobutylaluminum hydride to give (S)c-(S)s-β-hydroxy sulfoxides which were easily separated in an optically pure form by easy crystallization or separation by silica-gel chromatography due to the p-chlorophenyl moiety in the β-hydroxy sulfoxides. The utility of the present method could be successfully demonstrated in the synthesis of both (+)- and (−)-corynomycolic acids from optically pure methyl esters of (R)- and (S)-3-hydroxyoctadecanoic acid by alkylation with tetradecyl iodide at α-position and hydrolysis.
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