N-Hydroxyamide-containing Heterocycles. Part3. The Ring Transformation of 1-Benzoloxy-2(1H)-pyrimidinones into 2-Isoxazolines with Hydroxylamine

N-Benzyloxyurea was treated with various β-diketones in the presence of sulfuric acid in EtOH to give the corresponding 1-benzyloxy-2(1H)-pyri- midinones. 1-Benzyloxy-2(1H)-pyrimidinones underwent the ring transfor- mation with hydroxylamine to afford new 5-N-(benzyloxy)urea-attached 2-isoxazolines in addition to known isoxazoles. The MNDO molecular orbital calculation of 1-benzyloxy-4,6-dimethyl-2(1H)-pyrimidinone and the reaction mechanism are also discussed