Rh-Catalyzed Reactions of 3‑Diazo­indolin-2-imines: Synthesis of Pyrido­indoles and Tetra­hydro­furopyrrolo­indoles

The rhodium-catalyzed reactions of 3-diazoindolin-2-imines with furans and dihydrofuran furnished 9H-pyrido­[2,3-b]­indoles and tetrahydro­furo­[3′,2′:4,5]­pyrrolo­[2,3-b]­indoles, respectively. A cascade reaction mechanism involving an α-imino rhodium carbene intermediate is proposed. The starting materials are readily available, and the procedure is facile and efficient.