Nitrosation of methyl and phenyl styryl ketoximes under oxygen. Formation of 4-nitro-1-hydroxypyrazole 2-oxides and 3,5-diphenyl-4-nitrato-4,5-dihydroisoxazole

The nitrosation of the oximes of 4-phenyl-3-buten-2-one and 1,3-diphenyl-2-propen-1-one under oxygen has been reinvestigated. In addition to 4-oxo- and 4-oximino-4H-pyrazole 1,2-dioxides previously reported, the reactions give 4-nitro-1-hydroxypyrazole 2-oxides. In the case of 1,3-diphenyl-2-propen-1-one oxime the nitrosation reaction also gives 3,5-diphenyl-4-nitrato-4,5-dihydroisoxazole. Evidence is presented suggesting that the nitrate ester is formed through the rearrangement of a peroxynitrite intermediate.