Ring Transformation Reaction of 1, 4, 6-Trisubstituted 2 (1H)-Pyrimidinones and -Thiones with Hydroxylamine

Abstract

1, 4, 6-Trisubstituted 2 (1H)-pyrimidinones (Ia-e) underwent ring transformation with hydroxylamine to afford 3, 5-disubstituted isoxazoles (IIa-e) in high yields. On the other hand, 2 (1H)-pyrimidinethiones (IIIa, b, f-k) underwent ring transformation to give mainly a new type of N-substituted 2-aminopyrimidine 1-oxides (IVa, b, f-k) as well as isoxazoles. The reaction of pyrimidinium salts (VII, VIII and IX) with hydroxylamine is also discussed.