Site‐Selective N‐1 and C‐3 Heteroarylation of Indole with Heteroarylnitriles by Organocatalysis under Visible Light

Abstract Site‐selective N ‐1 and C‐3 arylation of indole has been sought after because of the prevalent application of arylindoles and the intricate reactivities associated with the multiple sites of the N ‐unsubstituted indole. Represented herein is the first regioselective heteroarylation of indole via a radical–radical cross‐coupling by visible‐light irradiation. Steady and time‐resolved spectroscopic and computational studies revealed that the hydrogen‐bonding interaction of organic base and its conjugated acid, namely with indole and heteroarylnitrile, determined the reaction pathway, which underwent either proton‐coupled electron‐transfer or energy‐transfer for the subsequent radical–radical cross‐coupling, leading to the regioselective formation of C‐3 and N ‐1 heteroarylation of indoles, respectively. The parallel methodologies for regioisomeric N ‐1 and C‐3 heteroaryl indoles with good functional group compatibility could be applied to large‐scale synthesis and late‐stage derivatization of bioactive compounds under extremely mild reaction conditions.