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 CF3SO2Cl as both the CF3 and Cl source. In the
mechanistic pathway for this process, generation of the CF3 radical and chloride ion occurs by Ir­(ppy)3-photocatalyzed
reductive decomposition of CF3SO2Cl. The synthetically
important trifluoromethyl-substituted vinyl chlorides produced in
this process can be readily transformed to 1,1-bis-arylalkenes by
using Suzuki coupling.