Efficient Synthesis of 1,4,2‐Dioxazepines via 4+3 Cyclization of p ‐QMs With In Situ Generated N ‐Electron‐Withdrawing Group Nitrones

ABSTRACT An efficient 4+3 cyclization strategy has been developed that exploits p ‐QMs and N ‐(EWG) nitrones generated in situ from N‐hydroxy(sulfonylmethyl)carbamates, enabling direct access to 1,4,2‐dioxazepines under mild conditions with broad substrate scope and gram‐scale scalability. This work expands the synthetic utility of N ‐(EWG) nitrones and offers a new route to dioxazepines.