3-Amino-4-cyanopyrazole I reacts with hydroxylamine and with hydrazine to yield 1H,6H-3-aminopyrazolo[3,4-c]pyrazole (III and IV). Diazotized IV couples with 2-naphthol to give the arylazo derivative VI which cyclizes to 9H-naphthol[2,1-e]pyrazolo[3',4':3,4]pyrazolo[5,1-c]-[1,2,4]triazine VII by means of acetic acid. The pyrazol-5-ylthiourea obtained from I and phenyl isothiocyanate undergoes base-catalyzed cyclization to give pyrazolo[3,4-d]pyrimidinethione derivative IX. Compound I reacts with cyclohexane in the presence of zinc chloride to give the tetrahydropyrazolo[3,4-b]quinoline derivative XI. The reaction of I with pyridine 1-oxide affords 4H,5H-pyrazolo[5',1':2,3] [1,2,4]triazolo[1,5-a]pyridine-3-carbonitrile XII.

The reaction of 5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carboxamide 2 with formamide, acetic anhydride and carbon disulphide yielded pyrimido[4′,5′ :4,5]thieno[2,3-c]-pyridazin-4-one derivatives. Pyrimido[4,5-c]pyridazinethione and dithione derivatives were obtained by cyclocondensation of 3-amino-5,6-diphenylpyridazine-4-carbonitrile (8) with phenyl isothiocyanate and carbon disulphide, respectively. Tetrahydropyridazino[3,4-b]-quinoline (11) was prepared by reaction of 8 with cyclohexanone in presence of zinc chloride.

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This paper discusses the utility of 4-(4-acetamidophenyl)-4-oxobut-2-enoic acid as a key starting material for the preparation of a novel series of pyridazinones, thiazoles derivatives, and other heterocycles via interaction with nitrogen, sulfur, and carbon nucleophiles under Michael addition conditions and studies the antimicrobial activities of some of these compounds.

a y p t . f&smct Condensation of 3-amino4cyanopyrazole (1) with ethylacetoacetate, ethyl cyanoacetate, diethy1 malonate and acetylacetone afforded pyrazolo[l,5-a]pyrimidine derivatives (2-8a). Other cqmpounds (Sb-b) of this ring system were obtained by treatment of 1 with arylidenemalononitrile and ethylarylidenecyanoacetate. And the reaction of compound (1) with activated acetylenes yeilded pyrazolo[l,5-~~pyrimidine derivatives (lla-b).A solution of 1 (1.08 g, 0.01 mole) and activated acetylenes (namely, methyl propiolate, ethyl propiolate and / or dimethyl acetylenedicarboxylate, 0.01 mole) in dioxane (20 mL) was refluxed for 10 h, the solvent was evaporated in vacuum and the residue was crystallized from suitable solvent to give lla, b.The characterization of these new compound are given in Table 1.