Cyclization of Alkyne–Azide with Isonitrile/CO via Self-Relay Rhodium Catalysis

A self-relay rhodium­(I)-catalyzed cyclization of alkyne–azides with two σ-donor/π-acceptor ligands (isonitriles and CO) to form sequentially multiple-fused heterocycle systems via tandem nitrene transformation and aza-Pauson–Khand cyclization has been developed. In this approach, an intriguing chemoselective insertion process of isonitriles superior to CO was observed. This reaction provides an alternative strategy to synthesize functionalized pyrrolo­[2,3-<i>b</i>]­indole scaffolds