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 fresh and lyophilised cells of seven yeasts was performed using ethyl acetoacetate and acetophenone as typical substrates. Lyophilised cells gave from low to high conversions but, with a few exceptions, always good enantioselectivity, and they were then employed for the reduction of structurally different carbonyl compounds. Highly enantioselective reduction of carbonyls was often achieved, even with aromatic ketones. Both enantiomers of the alcohols were, in most cases, obtained with high enantiomeric excess by simply choosing a suitable yeast.