Asymmetric Reduction of Aliphatic Short- to Long-Chain b-Keto Acids by Use of Fermenting Bakers' Yeast

Utaka, M.; Watabu, H.; Higashi, H.; Sakai, T.; Tsuboi, S.; Torii, S. J. Org. Chem. 1990, 55, 3917.

Eleven b-keto acids, ranging from 3-oxobutanoic to 3-oxooctanoic acids, were reduced with fermenting bakers' yeast to the corresponding optically active b-hydroxy acids, which were isolated as the methyl esters. In all cases, the (R)-hydroxy acids were obtained in >98% ee, except for 3-oxobutanoic acid, which afforded the (S)-hydroxy acid in 86% ee. Inhibition of fermentation was observed for 3-oxoundecanoic to 3-oxotetradecanoic acids, leading to no reduction. Lowering of the substarate concentration was found to be appreciably effective in avoiding inhibition.