Synthesis of γ-Lactones Utilizing Ketoacids and Trimethylsulfoxonium Iodide.

The Johnson-Corey-Chaykovsky epoxidation is one of the oldest methods for the synthesis of terminal epoxides from carbonyl compounds. Herein we present a simplified extension of the Johnson-Corey-Chaykovsky epoxidation, where ketoacids are employed as the substrates and commercially available trimethylsulfoxonium iodide is employed as the carbon-atom homologating reagent. A variety of lactones are produced in a single step in synthetically useful yields.