Synthesis and antimicrobial activity of some new 4-hetarylpyrazole and furo[2,3-c]pyrazole derivatives

In continuation of our efforts to find a new class of antimicrobial agents, a series of 4-hetarylpyrazoles and furo[2,3-c]pyrazoles were prepared via the reaction of 2-chloro-1-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)ethanone (1) with an appropriate nucleophilic reagents. These compounds were screened for their antibacterial activity against Gram-positive bacteria (Bacillus subtilis and Bacillus thuringiensis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and antifungal activity against Fusarium oxysporum and Botrytis fabae. Among the synthesized compounds, 1-(5-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazole-4-yl)-2-methylfuran-3-yl)ethanone (12) showed equal activity with chloramphenicol against B. subtilis (MIC 3.125 μg/mL), while its activity was 50% lower than of chloramphenicol against B. thuringiensis. N-[(4Z)-3-Methyl-1-phenyl-1H-furo[2,3-c]pyrazol-4(5H)-ylidene]-1H-benzimidazol-2-amine (7) and 2-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-4H-furo[3,2-c]chromen-4-one (13) were found to exhibit the most potent in vitro antifungal activity with MICs (6.25 μg/mL) against B. fabae and F. oxysporum.