Sunlight Induced and Alternative Sc(OTf)3 Catalyzed Remote C−H Halogenation of Indoles

Abstract A mild and catalyst‐free sunlight induced protocol for the remote meta bromination of electron‐deficient indoles is described for the first time. Herein, N ‐bromosaccharin is activated by sunlight irradiation. Alternately, a synergistic activation model (Sc(OTf) 3 /HFIP) has also been developed for the activation of haloniums, complementary to the light induced strategy. In addition, the cascade C6‐H bromination and benzylic C−H oxidation under photocatalytic conditions was also discussed. High regio‐and chem‐selectivity, mild reaction conditions, and scalability demonstrate great potential of the developed methods in practical applications and further functionalization.