NIS Mediated Cross-Coupling of C(sp2)–H and N–H Bonds: A Transition-Metal-Free Approach toward Indolo[1,2‑a]quinazolinones

A metal- and base-free protocol for intramolecular cross-coupling of C­(sp2)–H and N–H bonds using N-iodosuccinimide (NIS) has been demonstrated. This environmentally benign approach furnishes a series of substituted indolo­[1,2-a]­quinazolinones from the suitably fabricated indoles via C–N bond forming cyclization in 28–82% yield. A plausible mechanism is proposed for this cyclization based on the results of a control experiment. This methodology requires no additional metal catalyst, oxidant, or base. Furthermore, the synthetic utility of the protocol is demonstrated by performing a gram scale reaction.