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

A visible light promoted direct benzylic C-H difluoroalkylation with difluoroenoxysilanes catalyzed by Na-2-eosin Y via a HAT-ORPC pathway has been developed, providing an efficient and atom-economic method for difluoroalkylation of C(sp(3))-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 alpha-benzyl-alpha,alpha-difluoroketones in up to 96% yield.