Two novel hydroxyethyl pyrazolones were obtained by condensation of 2- hydroxyethylhydrazine with ethyl acetoacetate or ethyl benzoylacetate, later nitrosation of the C4 carbon atom in the heterocyclic moiety, afforded two novel oxime-derivatives. The 1H and 13C NMR data show that 1-(2-hydroxyethyl)-3-methyl-5-pyrazolone (1) is largely present together with a very small amount of the 5-one tautomer in DMSO-d6; in contrast, ...
