Cr-catalyzed difluoromethylation of α-trifluoromethyl alkenes for modular synthesis of polyfluorinated compounds.

We report a chromium-catalyzed allylic difluoromethylation of α-trifluoromethyl alkenes, allowing one-step access to polyfluorinated compounds characterised by both gem-difluoroalkene and difluoromethyl groups. The reaction employed inexpensive chromium as the catalyst and commercially available bench-stable difluoromethyl 2-pyridyl sulfone as the difluoromethylation reagent, and proceeded under mild conditions with a broad substrate scope. The mechanism studies performed indicated the involvement of radical species in this chromium-catalyzed difluoromethylation process. Gram-scale reactions and late-stage diversification of complex molecules were successfully executed.