Catalytic hydrotrifluoromethylation of styrenes and unactivated aliphatic alkenes via an organic photoredox system

Herein is presented a direct method for the metal-free hydrotrifluoromethylation of alkenes. The method relies on the single electron oxidation of a commercially available sodium trifluoromethanesulfinate salt (CF3SO2Na, Langlois reagent) by N-Me-9-mesityl acridinium as a photoredox catalyst. Methyl thiosalicylate is used as a substoichiometric H-atom donor for aliphatic alkenes, and thiophenol is used as a stoichiometric H-atom donor for styrenyl substrates. The substrate scope for the transformation is broad, including mono-, di- and trisubstituted aliphatic and styrenyl alkenes, with high regioselectivity in nearly all cases examined.