PPh₃-Mediated Cascade Reaction of 2-Alkynylnitrobenzenes and Thioureas for the Construction of Imidazo[4,5-<i>b</i>]indole-2-thiones

Abstract

A simple method for the preparation of imidazo[4,5-<i>b</i>]indole-2-thiones from 2-alkynylnitrobenzenes and thioureas is described. In the reaction, a Wittig-like process was triggered by PPh₃ and followed by a cyclization step. The products were afforded in yields of 70-98% under mild conditions. Additionally, the 2-alkynylnitrobenzenes were stable and could be prepared via a simple coupling step.