Ring-opening of isoxazolidine system: Homologation of 3-aryl into 3-styryl nitrones via intermediate 5-hydroxy-isoxazolidines

Article abstract of DOI:10.1016/S0040-4020(01)88315-0

High yield conversion of 3-aryl-5-ethoxy-isoxazolidines into 3-styryl nitrones has been achieved by 1,5 h refluxing in aq. H₂SO₄ or catalytic p-toluensulfonic acid/ethanol media. The rearrangement pathway is interpretable on the basis of the ring-opening process of intermediate 5-hydroxy-isoxazolidines. Formation of a masked 5-OH function has been also developed by basic or acid treatment of 5-acetoxy-isoxazolidines.