Synthesis of Fused Isoxazoles via Intramolecular Nitrile Oxide Cycloaddition

Abstract We report an efficient and straightforward strategy for the synthesis of substituted dihydrofuro[3,4‐c]isoxazoles and dihydro‐4H‐pyrano[4,3‐c]isoxazoles via intramolecular nitrile oxide cycloaddition (INOC) reactions of aldoximes, employing (diacetoxyiodo)benzene (PIDA/DIB/PhI(OAc)₂) as a single, cost‐effective oxidizing agent. This method enables the practical and economical synthesis of structurally diverse and highly functionalized oxygen‐bridged isoxazole derivatives under mild reaction condition with short reaction time.