ASYMMETRIC REDUCTION OF BETA-KETO-ESTERS WITH AN ENZYME FROM BAKERS-YEAST

Various beta-keto esters have been reduced by one of beta-keto ester reductases isolated from bakers' yeast. The corresponding beta-hydroxy esters have been obtained in excellent enantiomeric and diastereomeric excesses, respectively. It has also been elucidated that the reductase recognizes the stereochemistry not only at the beta-carbon but also at the alpha-carbon affording one of the four possible diastereoisomers of alpha-substituted beta-hydroxy esters predominantly. The stereoselectivity is excellent and chemical yields are moderate to good.