C−H Functionalization of Indoles by 3d Transition‐Metal Catalysis

Abstract Over the past decade, the use of 3d transition metal for the regioselective C−H bond functionalization of indoles has significantly increased. Particularly, advances in manganese, iron, cobalt, nickel and copper catalysis have demonstrated the selective C(2)−H and C(3)−H arylation, alkenylation, alkynylation and alkylation to a greater extent. Similarly, the C−O and C−N bond‐forming reactions are manifested via direct C−H bond activation by these earth‐abundant metals. The emergence of 3d metals in selective functionalization of the biologically relevant indoles and related heteroarenes would make this protocol more attractive for practical applications. Herein, we provide a brief overview of 3d transition metal‐catalyzed (mostly Mn, Fe, Co, Ni and Cu) C−H functionalization of indoles and related heteroarenes.