New Benzimidazoles Bearin 2-Pyrazoline Moiety: Synthesis and Antimicrobial Activity

Abstract

A new series of 5-(1H-Benzimidazol-2-yl)-4,5-dihydro-1H-pyrazol-3-yl] derivatives (1-9) were synthesized and characterized using spectral analysis. The first step includes the reaction of benzimidazole-2-carboxaldehyde with the o,p-aminoacetophenone to obtain the chalcone derivative (1, 2). The cyclization reaction of chalcone by the hydrazine hydrate afforded compound (3, 4), which represents the starting material for Schiff base derivatives. New Schiff bases (5-6) were synthesized from the reaction of benzimidazole derivative (2) with the corresponding benzaldehydes. The azetidin-2-one (7) and 1,3-oxazepane-4,7-dione derivatives (8-9) were synthesized from the corresponding aldehyde with chloroacetyl chloride and appropriate anhydride as depicted in the experimental section. All the derivatives were in vitro screened against Escherichia coli, Klebsiella spp. (Gram negative), Staphylococcus aureus, S.espidermi (Gram positive) as well as Candida albicans and found to exhibit moderate to potent activity.