, synthesis and antibacteial activity of novel pyrazolyl-dihydropyrimidinones

A series of new pyrazolyl-dihydropyrimidinones 4(a-g) have been synthesized from 3,5-dimethyl-1-aryl-1H-4-pyrazolecarbaldehyde 3(a-g). The structures of the synthesized compounds have been confirmed via IR, 1H NMR, 13C NMR and MS spectral analyses. Further, all the synthesized new compounds 4(a-g) have been assayed for their antibacterial activity against Gram-positive bacteria viz. Bacillus subtilis, Bacillus sphaericus and Staphylococcus aureus, and Gram-negative bacteria viz. Pseudomonas aeruginosa, Klobsinella aerogenes and Chromobacterium violaceum. The antibacterial screening data reveal that, compounds 4 which contain 3-flourophenyl (4c), 4-chlorophenyl (4d) and benzyl (4g) moieties on pyrazole ring might be the reason for the significant inhibitory activity. Most of these new compounds showed appreciable activity against test bacteria and emerged as potential molecules for further development.