Concise and Efficient Synthesis of Indole–Indolone Scaffolds through MeOTf-Induced Annulation of N‑(2-Cyanoaryl)indoles

MeOTf-triggered annulation of N-(2-cyanoaryl)­indoles to provide indolo­[1,2-a]­indol-10-imines and the corresponding indolo­[1,2-a]­indol-10-ones have been described under metal-free conditions. A variety of functional groups are tolerated in their scaffolds with good to excellent yields. The reaction could be carried to gram scale.