Catalytic Defluoroalkylation of Trifluoromethylaromatics with Unactivated Alkenes.

We describe a new catalytic approach to selective functionalization of the strong C-F bonds in trifluoromethylaromatic (Ar-CF) systems. In this approach, single electron reduction of Ar-CF substrates (using a photoredox catalyst) results in difluorobenzylic radical formation through a C-F cleavage mechanism. These radicals undergo efficient intermolecular coupling with simple alkenes in a defluoroalkylation process where radical termination is accomplished by a polarity reversal catalyst. This mild catalytic protocol engages a wide range of substrates to give medicinally relevant fluorinated substructures with complete regiocontrol.