Base-mediated [4 + 3] annulation of α-halogen hydroximate with o-QMs: Facile access to 1, 4-benzoxazepine scaffold

An efficient and facile approach to 1, 4-benzoxazepine was developed from α-halogen hydroximate and o-QMs. This protocol underwent formal [4 + 3] annulation process smoothly under mild reaction conditions to afford the desired products in moderate to excellent yields. A plausible mechanism was proposed.