Copper-catalyzed intermolecular carboesterification of unactivated aliphatic alkenes with α-carbonyl alkyl bromides via a SET process: efficient synthesis of γ-lactones

Abstract

A novel and efficient copper-catalyzed carboesterification of unactivated alkenes with α-carbonyl alkyl bromides for the synthesis of γ-lactones derivatives has been developed. With the assistance of a removable bidentate 8-aminoquinoline directing group, various γ-lactones derivatives were prepared with excellent regioselectivity using the inexpensive copper powder as a catalyst. This reaction could be compatible with unactivated alkenes and alkyl bromides bearing various functional groups. The further resultant functionalized γ-lactones displayed easy transformation in organic synthesis and potential application with industrial perspective. Preliminary mechanistic experiments showed that the oxygen atom of the newly formed ester group or the carbonyl group was not originated from the trace amount of water in the reaction system and the carboesterification of unactivated alkenes might proceed via a radical process.