Convenient synthesis and antibacterial evaluation of new bipyrazolyl and pyrazolopyridazine derivatives utilizing 4-acetyl-5-methyl-N-phenyl-1-(p-tolyl)-1H-pyrazole-3-carboxamide as a versatile precursor

Abstract

4-(3-(Dimethylamino)acryloyl)-5-methyl-N-phenyl-1-(p-tolyl)-1H-pyrazole-3-carboxamide was prepared via refluxing of 4-acetyl-5-methyl-N-phenyl-1-(p-tolyl)-1H-pyrazole-3-carboxamide with dimethylformamide dimethyl acetal. The target bipyrazoles were obtained from regioselective reaction of the latter enaminone with different hydrazonoyl halides at reflux in chloroform in the presence of trimethylamine. The regioselectivity was confirmed chemically upon refluxing with hydrazine hydrate in ethanol. The structures of the newly synthesized compounds were established on the basis of their elemental analyses and spectral data. The specified compounds were tested for antibacterial activity against gram-negative bacteria (Escherichia coli) and (Pseudomonas aeruginosa) and a gram-positive bacteria (Bacillus subtilis) and (Staphylococcus aureus) using disk diffusion method. Antibacterial studies revealed that compounds 8a, 10b, 10c, 11d, and 14b showed weak to moderate activity against the tested bacteria compared to ampicillin.