Lyophilised yeasts: easy-to-handle biocatalysts for stereoselective reduction of ketones

The use of lyophilised yeasts as biocatalysts for the reduction of carbonyl compounds has been studied. First, a comparison of the performances of fre sh and lyophilised cells of seven yeasts was performed using ethyl acetoace tate and acetophenone as typical substrates. Lyophilised cells gave from lo w to high conversions but, with a few exceptions, always good enantioselect ivity, and they were then employed for the reduction of structurally differ ent carbonyl compounds. Highly enantioselective reduction of carbonyls was often achieved, even with aromatic ketones. Both enantiomers of the alcohol s were, in most cases, obtained with high enantiomeric excess by simply cho osing a suitable yeast. (C) 1999 Published by Elsevier Science Ltd. All rig hts reserved.