Microbiological asymmetric reduction of methyl 3-(2-furyl)-2-methyl-3-oxopropionate (5) by various yeasts was carried out. Four kinds of methyl 3-(2-furyl)-3-hydroxy-2-methyl propionates (6a-6d) could be obtained separately from the prochiral β-keto ester 5 by reduction with properly selected microorganisms. In particular, the desired syn-isomer 6a was obtained with high optical purity (>99% e.e.). Both the chemical yield and the optical purity of the reduction products (6a-6d) were significantly improved when fermentation was carried out on a large scale using a 30 1 jar fermentor or a 200 1 tank.
