Direct benzylic C–H difluoroalkylation with difluoroenoxysilanes by transition metal-free photoredox catalysis

Abstract

A visible light promoted direct benzylic C–H difluoroalkylation with difluoroenoxysilanes catalyzed by Na₂-eosin Y via a HAT-ORPC pathway has been developed, providing an efficient and atom-economic method for difluoroalkylation of C(sp³)-based substrates. A transition metal-free organic photocatalyst, mild reaction conditions and a green oxidant of air show great advantages in environmental friendliness. Various substituted xanthenes, acridines and thioxanthene are found to be efficient substrates to construct pharmaceutically important α-benzyl-α,α-difluoroketones in up to 96% yield.