Synthesis of some new 1-(5-((1H-pyrazol-1-yl)methyl)-2-aryl-1,3,4-oxadiazol-3(2H)-yl) ethanone derivatives and study their antimicrobial activity

Ethyl 2-(1H-pyrazol-1-yl)acetate (1) was synthesized by the reaction of ethylchloroacetate with 1H-pyrazole, Then compound (1) refluxed with hydrazine hydrate to get 2-(1H-pyrazol-1-yl) acetohydrazide (2). Compound (2) was reaction with appropriate aryl aldehyde to get schiff bases N'-arylidine-2-(1H-pyrazol-1-yl)acetohydrazide derivatives (3a-3f). schiff’s base (3a-3e) were cyclized by reflux with acetic anhydride to get new 1-(5-((1H-pyrazol-1-yl)methyl)-2-aryl-1,3,4-oxadiazol-3(2H)-yl)ethanone derivatives (4a-4e). The structures of the synthesized compounds were characterized by IR, 1H-NMR, 13C-NMR, mass spectra, and elemental analysis data. Synthesized compounds (4a-4e) were evaluated as antibacterial agents against some common pathogenic bacteria Gram-positive (Staphylococcus aureus, Streptococcus pyogenes) and Gram-negative bacteria (Escherichia coli, Psuedomonas aeruginosa). The result of antibacterial activity was compared with standard drugs (Ciprofloxacin and Tetracycline).