NITROSATION OF ALPHA,BETA-UNSATURATED OXIMES .5. SYNTHESIS AND CHEMISTRY OF 1-HYDROXYPYRAZOLE 2-OXIDES

Nitrosation of α-substituted α,β-unsaturated oximes with sodium nitrite in acetic acid produces 1-hydroxypyrazole 2-oxides (3). These compounds are relatively strong organic acids and form chelates with a variety of transition metals. Reduction yields the corresponding N-hydroxypyrazoles or the parent pyrazoles. Acylation leads to a molecular rearrangement and production of 3-acyloxypyrazolenine 1-oxides (10). Nitrosation converts the 4-alkyl derivatives into 4-nitro-1,2-diazacyclopentadiene 1,2-dioxides (16). © 1969, American Chemical Society. All rights reserved.