Synthesis of 2‑Amino-2′-hydroxy-1,1′-biaryls via Cascade Benzannulation and C–N Bond Cleavage Sequence

A serendipitous synthesis of N-substituted 2-amino-2′-hydroxy-1,1′-biaryls through an aryne annulation with indolyl β-ketonitrile/ester in a cascade manner is demonstrated. The reaction sequence involves benzyne-mediated [2 + 2] Stoltz-type cycloaddition–cleavage and intramolecular Michael addition followed by C–N bond cleavage under transition-metal-free reaction conditions. Interestingly, while [4 + 2] Diels–Alder reaction is a possible pathway, no traces of the regioisomer was isolated.