From Indoles to Carbazoles: Tandem Cp*Rh(III)-Catalyzed C–H Activation/Brønsted Acid-Catalyzed Cyclization Reactions

A tandem Cp*Rh(III)-catalyzed C–H activation/Brønsted acid-catalyzed intramolecular cyclization allows a facile synthesis of carbazoles from readily available indoles. The reaction proceeds under rather mild reaction conditions with the generation of water and N2 as the only byproducts. Broad substrate scope, excellent functional group tolerance, and high yields were observed. The benzannulation of pyroles for the synthesis of indoles is also feasible using the same protocol.