Palladium-catalyzed [5+2] cycloaddition of vinyloxiranes with photogenerated siloxyketenes: access to seven-membered lactones

Abstract

A visible-light-driven, palladium-catalyzed [5+2] cycloaddition of α-ketoacylsilanes with vinyloxiranes has been developed. This method features mild conditions, broad substrate scope, and good functional group tolerance, enabling the synthesis of seven-membered lactones bearing a tertiary alcohol motif (up to 90% yield). The synthetic utility is demonstrated by scale-up reactions and downstream transformations. Furthermore, the catalytic asymmetric version has also been explored. This work expands the application of α-ketoacylsilanes as siloxyketene precursors and provides a new strategy for constructing medium-sized rings under mild conditions.