An α-acetoxy ketone reducing enzyme has been purified and characterized from the cell-free extract of bakers’ yeast (Saccharomyces cerevisiae). Only one NADPH-dependent dehydrogenase that catalyzed the reduction of α-acetoxy ketone was found in bakers’ yeast. The molecular weight of the enzyme was estimated to be 36 kDa by SDS-polyacrylamide gel electrophoresis. The enzyme was composed of a single
Bakers' yeastreduction of 1-chloro-2,4-alkanediones 1a afforded 1-chloro-2-hydroxy-4-alkanones 2a regioselectively with low opticalpurities. Application of inhibitors and heat-treatment of bakers' yeast enhanced the opticalpurities toward the S enantiomer (88–91% ee). Organic solvents added in small amounts were also found to enhance the S selectivity significantly. Highopticalpurities of 94–96%