Rhodium-Catalyzed Intramolecular Nitrogen Atom Insertion into Arene Rings

In this study, we describe the direct insertion of an intramolecular nitrogen atom into an aromatic C–C bond. In this transformation, carbamoyl azides are activated by a Rh catalyst and subsequently directly inserted into the C–C bond of an arene ring to access fused azepine products. This transformation is challenging, owing to the existence of a competitive C–H amination pathway. The use of a paddlewheel dirhodium complex Rh2(esp)2 effectively inhibited the undesired C–H insertion. Density functional theory calculations were performed to reveal the reaction mechanism and origin of the chemoselectivity of the Rh-catalyzed reactions. The novel fused azepine products are highly robust and allow for downstream diversification.