RESUMO
Dyrazole derivatives have shown bacteriocidal and fungicidal actions. On the other hand, pyridazine compounds exhibit therapeutic and plant growth regulating effects. It was of interest to synthesize molecules bearing both pyrazole and pyridazine moities such as 6-aryl-2,3,4,5-tetrahydro-4 [2 [3,5-dimethyl] pyrazolyl] pyridazin-3-ones [IVa-d]. Pyrazoles undergo Michael addition to alpha, Beta unsaturated acids and esters. In the present work we reinvestigated the problem of Michael type addition to pyrazoles to Beta-aroylacrylic acid. Thus when 3,5-dimethylpy-razole [I] was refluxed for two hours with Beta aroylacrylic acid [IIa, b] in toluene, Beta-aroyl-alpha [2 [3,5-dimethyl] pyrazolyl] propionic acid [IIIa, b] was formed. The structure of III was inferred from analytical and spectral data. Compounds IIIa, b were allowed to react with hydrazine hydrate and/or phenylhydrazine in n-butanol under reflux, whereby the corresponding 6-aryl-2,3,4,5-tetrahydro-4 [2[3,5-dimethyl] pyrazolyl] pyridazin-3-ones [IV a-d] were formed. The structure of IV was established based on analytical and spectral data. Compounds IIIa, b reacted with hydroxylamine in pyridine under reflux to yield the corresponding oxime [Va, b]. The structure of V was assigned from analytical and IR data