Domino Aryne Annulation via a Nucleophilic–Ene Process

1,2-Benzdiyne equivalents possess the unique property that they can react with two aryno­philes through iteratively generated 1,2- and 2,3-aryne intermediates. Upon rational modification on the second leaving group of these aryne precursors, a domino aryne annulation approach was developed through a nucleophilic–ene reaction sequence. Various benzo-fused N-heterocyclic frameworks were achievable under transition metal-free conditions with a broad substrate scope.