Synthesis, characterization and antibacterial activity of 2-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1 H-pyrazol-4-yl]-5-(substituted-phenyl)-[1,3,4]oxadiazoles

• Published in: European journal of medicinal chemistry 2009-11, Vol.44 (11), p.4522-4527
• Main Authors: Rai, Neithnadka Premsai, Narayanaswamy, Venugopala Katharigatta, Shashikanth, Sheena, Arunachalam, Pirama Nayagam
• Format: Article
• Language: English
• Subjects: 2-[1-(5-Chloro-2-methoxy-phenyl)-5-methyl-1 H-pyrazol-4-yl]-5-(substituted-phenyl)-[1,3,4]oxadiazoles; Anti-Bacterial Agents - chemical synthesis; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Antibacterial agents; Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacillus subtilis - drug effects; Bacteria - drug effects; Biological and medical sciences; Escherichia coli - drug effects; Klebsiella pneumoniae - drug effects; Medical sciences; Microbial Sensitivity Tests; Minimum inhibitory concentration; Oxadiazoles - chemical synthesis; Oxadiazoles - chemistry; Oxadiazoles - pharmacology; Pharmacology. Drug treatments; Staphylococcus aureus - drug effects; Structure-Activity Relationship
• ISSN: 0223-5234; 1768-3254
• DOI: 10.1016/j.ejmech.2009.06.020

In the present investigation a series of novel 2-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1 H-pyrazol-4-yl]-5-(substituted-phenyl)-[1,3,4]oxadiazoles ( 4a– j) were synthesized by cyclization of substituted-benzoic acid N′-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1 H-pyrazole-4-carbonyl]-hydrazide by using phosphorousoxychloride at 120 °C. The chemical structure of the newly synthesized compounds was characterized by analytical and spectral (IR, 1H NMR, 13C NMR and LC–MS) methods. The title compounds were screened for qualitative (zone of inhibition) and quantitative antibacterial activity (MIC) by agar cup plate and microtitration methods, respectively. Among the synthesized compounds in this series compound 2-[1-(5-chloro-2-methoxyphenyl)-5-methyl-1 H-pyrazol-4-yl]-5-(4-fluorophenyl)-1,3,4-oxadiazole ( 4b) was found to exhibit significant antibacterial activity with MICs of 22.4, 29.8, 29.6 and 30.0 μg/mL against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae, respectively. The other compounds exhibited moderate activity when compared to standard substance Ampicillin. In the present investigation a series of novel 2-[1-(5-chloro-2-methoxy-phenyl)-5-methyl-1 H-pyrazol-4-yl]-5-(substituted-phenyl)-[1,3,4]oxadiazoles ( 4a– j) were synthesized and screened for qualitative (zone of inhibition) and quantitative antibacterial activity (MIC). [Display omitted]