Skeletal rearrangement of N,O-heterocycles. The isoxazolinone to aziridine transformation induced by lithium aluminum hydride

Triphenylisoxazolinone reacts with lithium aluminum hydride to yield either triphenylaziridinic derivatives or open-ring products or both depending on-reaction conditions. The structures of the products were ascertained by spectroscopic methods and their stereochemistry was assigned on the basis of lanthanide shift experiments. The main features of the reaction mechanism are also discussed in terms of quantum-mechanical calculations by CNDO/2. The rearrangement under study appears to proceed through a concerted [1,3]-sigmatropic migration of the nitrogen to a carbon of the isoxazolinic enolate system as shown by the HOMO-LUMO interactions possible.