Synthesis of Isoxazol-5(2 H )-one Derivatives via ( t BuO) 2 Mg Promoted [3 + 2] Annulations of δ-Acetoxy Allenoates with Hydroxylamine.

Herein, an efficient ( t BuO) 2 Mg promoted [3 + 2] annulation of δ-acetoxy allenoates with N -benzylhydroxylamine has been developed. This method provides a concise and facile protocol to synthesize vinylated isoxazol-5(2 H )-one derivatives stereospecifically in a broad substrate scope with high efficiency (31 examples, up to 87% yield).