The Use of Microorganisms in Organic Synthesis. II. Microbiological Asymmetric Reduction of 2-Methyl-3-oxosuccinates

Abstract

In order to synthesize four optically active methyl 2-methylmalates (10-13), microbiological asymmetric reduction of the corresponding dimethyl 2-methyl-3-oxosuccinate (9) was carried out. The β-keto diester 9 was found to be reduced by fermenting baker's yeast (Saccharomyces cerevisiae) and Candida albicans to afford a mixture of the (2R, 3R)-isomer 10 and the (2S, 3R)-isomer 11. Although the optical purity of 10 produced by Candida albicans was reasonably high (95% e.e.), optical yields of other products were unexpectedly low. However, identification of the four possible isomers 14-17 was found to be easily carried out by means of nuclear magnetic resonance spectroscopy.