Enantioselective synthesis of gamma-aryl-gamma-butyrolactones by sequential asymmetric epoxidation, ring expansion, and Baeyer-Villiger oxidation

This paper describes an enantioselective synthesis of gamma-butyrolactones, using the N-tolyl-substituted oxazolidinone-containing ketone as catalyst and Oxone as oxidant via a sequential asymmetric epoxidation of benzylidenecyclopropanes, ring expansion, and Baeyer-Villiger oxidation. Up to 91% ee was obtained. Optically active cyclobutanones can also be obtained by suppressing the Baeyer-Villiger oxidation with use of more ketone catalyst and less Oxone.