Synthesis, characterization, and antimicrobial activity of pyrazol-3-yl-pyrimidine, pyrazole and pyran derivatives

A series of novel pyrazol-3-yl-pyrimidine, pyrazole, and pyran derivatives have been synthesized in good yields. Thus, the reaction of 5-oxo-1-phenyl-4-(2-phenylhydrazono)-4.5-dihydro-1H-pyrazole-3-carbaldehyde(1) with malononitrile mixture with thiourea, guanidine hydrochloride, barbituric acid, thiosemicarbazide, or phenyl thiosemicarbazide in one-pot synthesis produced the corresponding compounds (2-6). treatment of (2) with o-bromobenzoic acid gave compound (7). Similarly, treatment of (1), malononitrile mixture with hydrazine hydrate, o-nitrophenyl hydrazine, isonicotinoylhydrazine, p-sulphamylphenylhydrazine, or phenyl hydrazine yielded the corresponding (8-12). In the same time, treatment of (1), malononitrile mixture with cyclohexanone, dimedone or acetophenone, afforded the pyrazolyl-pyran derivatives (13-15). In addition, treatment of (15) with methylhydrazine gavemethylaminopyridine-5-carbonitrilederivative (16). The Reaction of (1), malononitrile mixture with hydroxylamine hydrochloride gave 2, 3-dihydroisoxazole-4-carbonitrile derivative (17) and with oxamic acid gave5, 6-dioxo-5, 6-dihydropyridine-5-carbonitrilederivative (18). The structure of all target molecules (2-18) have been confirmed by various spectral techniques and elemental analyses. The synthesized compounds were screened for antimicrobial activity.