Heteroannulation of 3‑Nitroindoles and 3‑Nitrobenzo[b]thiophenes: A Multicomponent Approach toward Pyrrole-Fused Heterocycles

A simple, efficient, and general multicomponent reaction involving an enolizable ketone, a primary amine, and an N-protected 3-nitroindole was developed for the synthesis of a range of functionalized pyrrolo­[3,2-b]­indoles. The methodology was efficaciously utilized for the “pyrroloindoliztion” of natural products, the pyrrolization of 3-nitrobenzo­[b]­thiophene, and the gram-scale synthesis of pyrroloindole. Furthermore, a “one-pot” approach for accessing indolo­[3,2-b]­indoles was realized.