N-Heterocyclic Nitrenium-Catalyzed Photohomolysis of CF 3 SO 2 Cl for Alkene Trifluoromethylation.

N-Heterocyclic nitreniums (NHNs) have been utilized as Lewis acid catalysts to activate substrates with lone pairs. Alternative to their conventional applications, we have discovered that NHNs can also serve as charge transfer complex catalysts. Herein, we present another potential of NHNs by utilizing a weak interaction between NHNs and CF 3 SO 2 Cl. The method promotes CF 3 SO 2 Cl to undergo photohomolysis, resulting in the CF 3 radical. Mechanistic studies suggested that the weak interaction could be due to the π-hole effect of NHNs.