Synthesis and evaluation of 2-(5-(aryl)-1,3,4-oxadiazol-2-ylthio)-N-(3-(trifluoromethyl)phenyl)acetamides and N-(4-chloro-3-fluorophenyl)-2-(5-(aryl)-1,3,4-oxadiazol-2-ylthio)acetamides as antimicrobial agents

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A series of 2-mercapto-5-phenyl-1,3,4-oxadiazole derivatives have been condensed with different phenyl acetamide derivatives possessing fluorine atom at meta position; resulting in the formation of 2-(5-aryl-1,3,4-oxadiazol-2-ylthio)-N-(3-(trifluoromethyl)phenyl)acetamide (5a–j) and N-(4-chloro-3-fluorophenyl)-2-(5-aryl-1,3,4-oxadiazol-2-ylthio)acetamide (5k–t) derivatives. The antimicrobial properties of the synthesized entities (5a–t) measured as their MIC (Minimum Inhibitory Concentration) values were evaluated by using the broth dilution method against Gram-positive bacteria (S. aureus and E. faecalis), Gram-negative bacteria (E. coli and P. aeruginosa) and fungi (C. albicans and A. niger). The results of antimicrobial activities (in μg/ml) revealed the fact that the compounds 5a and g bearing a maximum number of fluorine atoms showed the highest potency among the synthesized compounds against the broad panel of bacterial and fungal strains. The presence of fluorine atom at the meta position in the phenyl ring of final derivatives (5a–t) brought about an enhancement of their antimicrobial properties to a notable extent. Two novel series of oxadiazole bearing fluoro substituted acetamides were synthesized and characterized using different spectral techniques. In vitro antimicrobial test results and SAR study helped to conclude that electron-withdrawing substituent as well as presence of fluorine atoms play important role in increasing the antibacterial and antifungal potency of synthesized derivatives.