Urea derivatives of piperazine doped with pyrazole‐4‐carboxylic acids: Synthesis and antimicrobial evaluation

Abstract A series of novel N ‐cycloalkyl/aryl‐4‐(1,3‐diphenyl‐1 H ‐pyrazole‐4‐carbonyl)piperazine‐1‐carboxamides 9a‐g has been synthesized for biological interest by simple base catalyzed reaction of various N ‐cycloalkyl/aryl isocyanates with (1,3‐diphenyl‐1 H ‐pyrazol‐4‐yl)(piperazin‐1‐yl)methanone hydrochloride 8 . The compound 8 was synthesized in excellent yield by the reaction of 1,3‐diphenyl‐1 H ‐pyrazole‐4‐carbonyl chloride with boc‐piperazine followed by deprotection of boc group with dioxane‐HCl. All the novel intermediates and urea derivatives have been screened for antimicrobial activity. The compound 9a was found an excellent compound to be active against all Gram (−ve) and Gram (+ve) bacterial strains E. coli , Y. enterocolitica , B. cereus , and S. aureus . It also showed comparable antifungal activity against C. albicans with MIC 78.1 μg/ml as compared to reference standard miconazole.