Stereoselective Photoredox-Catalyzed Chlorotrifluoromethylation of Alkynes: Synthesis of Tetrasubstituted Alkenes

A new photoredox-catalyzed chlorotrifluoromethylation reaction of internal arylalkynes under mild conditions using visible light has been developed. The reactions proceed with high levels of regio- and stereoselectivity and utilize commercially available CF 3 SO 2 Cl as both the CF 3 and Cl source. In the mechanistic pathway for this process, generation of the CF 3 radical and chloride ion occurs by Ir(ppy) 3 -photocatalyzed reductive decomposition of CF 3 SO 2 Cl. The synthetically important trifluoromethyl-substituted vinyl chlorides produced in this process can be readily transformed to 1,1-bis-arylalkenes by using Suzuki coupling.