Microwave‐Assisted, Solvent‐Free, One‐Pot Synthesis of Bioactive Imidazolyl‐Pyrazole and Imidazole Derivatives Catalyzed by Mesolite‐Type Natural Zeolite

ABSTRACT An efficient method has been developed for the synthesis of Imidazolyl‐Pyrazole and imidazole derivatives by cyclo‐condensation (MCR) of 1,3‐diphenylpyrazole‐4‐carbaldehyde or benzaldehyde, benzil, substituted anilines, and ammonium acetate, using mesolite‐type natural zeolite as an efficient and heterogeneous solid acid catalyst under microwave irradiation. The reaction proceeds with a high yield of up to 75%–96% within a short reaction time (17–18 min) as compared with reflux conditions. Further, the synthesized imidazolyl‐pyrazole derivatives were characterized by FT‐IR, 1 H‐NMR, 1 3 C‐NMR, and LC‐MS analytical techniques and screened for in vitro antimicrobial activity using the agar diffusion method. Derivative 1(a) shows greater antimicrobial activity with MIC 25 µg/mL against Streptococcus pyogenes . The derivatives 1(a) and 1(c) showed superior activity against Candida albicans with MIC 250 µg/mL.