Visible-Light-Induced Difluoroalkylation of 1-(Allyloxy)-2-(1-arylvinyl)benzenes and 1-(1-Arylvinyl)-2-(vinyloxy)benzenes: Synthesis of Bis-Difluoroalkylated Benzoxepines and 2H-Chromenes.

A novel visible-light-mediated difluoroalkylation of 1-(allyloxy)-2-(1-arylvinyl)benzenes and 1-(1-arylvinyl)-2-(vinyloxy)benzenes for the synthesis of bis-difluoroalkylated benzoxepines and 2H-chromenes is developed. This method features mild reaction conditions, good regioselectivity, a wide substrate scope, good functional-group compatibility, and late-stage modification. Preliminary mechanistic studies reveal that the generation of the CF2CO2Et radical is more prone to reaction with the double bond of the aryl group.