Visible‐light photoredox catalyzed synthesis of tetrahydrobenzofuranone: Oxidative [3 + 2] cycloaddition of dicarbonyl and alkene

Abstract Visible‐light‐mediated formation of tetrahydrobenzofuranone by direct oxidative [3 + 2] cycloaddition via coupling between dimedone and chalcone using eosin‐Y as a photoredox catalyst has been reported. The reaction takes place by a radical pathway as evidenced from our experiments and literature. The developed method involves the utilization of visible‐light photoredox catalysis for the formation of C‐C and C‐O bond via abstraction of methylinic hydrogen of dimedone and β ‐carbon of chalcone as well as coupling between carbonyl group of dimedone and α‐carbon of chalcone in tetrahydrobenzofuranone in one‐pot procedure. The present protocol shows significant advantages such as the application of visible light as a clean source of energy, green solvent, mild reaction conditions, cost effectiveness, short reaction time, metal free synthesis, easy operation, high atom economy, and broad substrate scope with functional group tolerance. Moreover, outstanding yield of the product obtained up to 82%.