Preparative β-Ketoester Reductions and Ester Hydrolyses by Yeast, Using Free Cells in Organic Media

Abstract

Free cells of yeast have been used for preparative β-ketoester reductions and ester hydrolyses in a mixture of isopropyl hexadecanoate and soybean phospholipids. The commercially available pressed lager baker’s yeast was used without adding water to the organic medium. In this way, ca. 50 g substrate could be easily converted by 500-700 g yeast in a 1.5 L volume, thus surpassing the reported procedures in aqueous media. Switching from aqueous to organic medium led, in a couple of cases, to an increase of the enantioselectivity from 90% (in water) to > 99% ee (in the organic medium) for ketone reduction and from 74 % to > 99 % ee for ester hydrolysis as compared to the best reported data for aqueous conditions.