REDUCTION OF 2-SUBSTITUTED CYCLOHEXANONES BY SACCHAROMYCES-CEREVISIAE

An enzymatic reduction of 2-substituted cyclohexanones mediated by Sac charomyces cerevisiae was studied with respect to the stereochemical c ourse and optical purity of the products. Reduction of ketones 1b-1f r esulted in separable diastereoisomeric mixtures of cis- and trans-ster eoisomers of 2-substituted cyclohexanols (2b-2f and 3b-3f) having the (S) absolute configuration at the chiral center bearing the hydroxyl f unctionality with high enantiomeric purity. Reduction of ketone 1a yie lded mixture of cis-(1S, 2R)- and trans-(1R,2R)-stereoisomers (2a and 3a) with lower enantiomeric purity. Changes in the nature of the C(2)- substituent affect the stereochemical course of the biotransformation. However, they significantly influenced the enantiomeric purity of the products. The diastereoselectivity of the process was studied as well ; high diastereoselectivity was observed with the substrates 1a, 1e an d 1f.