Synthesis of some 1,3,4-Oxadiazole Derivatives by Oxidative Cyclization Method and studying their Biological Activity

Abstract

This study included preparation of hydrazide derivatives (A2- A4) by reaction of carboxylic acid esters with hydrazine hydrate in absolute ethanol. Hydrazone derivatives (A5- A19) were prepared by condensation of hydrazide derivatives with appropriate aromatic aldehydes absolute ethanol, then they were converted to 1, 3, 4- oxadiazole derivatives (A20- A34) by treating with lead dioxide in glacial acetic acid at room temperature .The Structure of the synthesized compounds were confirmed by I.R and U.V spectral data , Thin Layer Chromatography (T. L. C) as well as their physical properties.This study also included the studying the effect of some prepared compounds (A7, A12, A13, A14, A17, A20, A22, A23, A24, A25, A26, A28) on the growth of four types of germs which are known in their resistance to antibiotics, and they were Escherichia coli, Pseudomonas aeruginosa (gram negative) and Staphylococcus aureus, Streptococcuse pyogenes (gram positive). The sensitivity of these compounds is tested on depending on the measurement of inhibition zone. It was noticed that these compounds showed high activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, where a low activity against streptococcus pyogenes.The extent of influence of these compounds was compared with three standard antibiotics as controlling samples and they were: Chloramphenicol, Cephalaxine, and Gentamycin.