Regio- and enantioselective reduction of methyleneketoesters mediated by Saccharomyces cerevisiae

Methyleneketoesters were readily prepared in high yields by performing a direct α-methylenation of the corresponding ketoesters using a previously described protocol. Reactions of ethyl 2-methylene-3-oxo-3-arylpropanoates 2a–c catalyzed by S. cerevisiae were performed with good conversions to give reductions of the CC, CO or both, depending on the reaction conditions and on the substitution of the aryl moiety. Reaction of 3-methylene-2-oxo-4-phenylbutyrate 2d was carried out with free yeast cells and with yeast cells immobilized with calcium alginate, in which the major products resulted from CC and CO bond reduction.