Enantioselective Synthesis of γ-Aryl-γ-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.