Reaction of 6-methyl-2-(2-oxo-2-phenyl-ethylidene)-2,3-dihydropyrimidin-4(1H)-one with hydrazine and hydroxylamine

The reaction of 6-methyl-2-(2-oxo-2-phenylethylidene)-2,3-dihydropyrimidin-4(1H)-one and of its nitrosation product with hydroxylamine stops at the stage of forming the corresponding oximes. The reaction of 6-methyl-2-(2-oxo-2-phenylethylidene)-2,3-dihydropyrimidin-4(1H)-one with hydrazine yields a mixture of 3-amino-5-phenylpyrazole and 3-methyl-2-pyrazolin-5-one in 71 and 62% yields, respectively. The ketoxime is used in the synthesis of a series of imidazole N(3)-oxides substituted at the 1, 4, and 5 positions of the imidazole ring.