Antimicrobial screening and one-pot synthesis of 4-(substituted-anilinomethyl)-3-(2-naphthyl)-1-phenyl-1H-pyrazole derivatives

Aim: Synthesis of series of 4-(substituted-anilinomethyl-3-(2-naphthyl)-1-phenyl-1H-pyrazole derivatives (4a-4k) and their in vitro antifungal and antibacterial screening. Materials and Methods: A series of compounds (4a-4k) was synthesized through direct reductive amination of 3-(naphthalen-2-yl)-1-phenyl-1H-pyrazole-4-carbaldehyde with various substituted aromatic amines using NaBH ₄ in the presence of I ₂ as reducing agent. The reaction was carried out in anhydrous methanol under neutral conditions at room temperature. The structures of synthesized compounds (4a-4k) were established on the basis of IR, ¹ H and ¹³ C-NMR, and mass spectral data. Results: All 4-(substituted-anilinomethyl-3-(2-naphthyl)-1-phenyl-1H-pyrazole derivatives (4a-4k) were tested in vitro for antifungal and antibacterial activities against different fungal and bacterial strains. Most of the compounds exhibited considerable antifungal activity, but poor antibacterial activity against the test strains. Conclusion: In the series compound 4e, 4g, 4j, and 4k, showed excellent antifungal activity against the fungal strain Aspergillus niger (MTCC) 281 and Aspergillus flavus MTCC 277 (% inhibition in the range of 47.7-58.9).