Asymmetric reduction of 3-aryl-3-keto esters using Rhizopus species

Ethyl 3-aryl-3-oxopropanoates (aryl: phenyl, 2-fluorophenyl, 3-nitrophenyl, and 4-nitrophenyl) were reduced enantioselectively to the corresponding (S)-alcohols by the fungus Rhizopus arrhizus and other Rhizopus sp. The best results were generally obtained with Rhizopus arrhizus (wild type) and Rhizopus nivius NCIM 958 with 6 h incubation. A longer incubation period led to ester hydrolysis followed by decarboxylation and microbial reduction for all the substrates especially the 3-nitrophenyl ester.