Transition-metal-free oxidative cyclization reaction of enynals to access pyrane-2-one derivatives

A novel and efficient metal-free C-H functionalization of enynals is developed to synthesize α -pyrone derivatives via the formation of two C-O bonds. In this project, K 2 S 2 O 8 has been introduced as an efficient oxygen source and C-H functionalization agent in regioselective oxidative cyclization reaction with a relatively broad substrate scope. K 2 S 2 O 8 is introduced as an oxygen source and C-H functionalization agent in a novel selective metal-free oxidative cyclization of enynals to synthesize α-pyrone derivatives with a relatively broad substrate scope via the formation of two C-O bonds.