Synthesis and antibacterial activity of some new 1,3,4-oxadiazoles and 1,3,4-thiadiazoles

Abstract

In this work the synthesis of some mono, disubstituted-1,3,4-oxadiazoles and 2-substituted-1,3,4-thiadiazoles are presented. Starting from some ethyl esters (1-4), the ester was treated with hydrazine hydrate in ethanol to give the corresponding hydrazides (5-8). The hydrazides then treated with formic acid to give 1-formyl-2-acyl hydrazine (9-12), the synthesized 1-formyl derivatives were converted to 2-substituted-1,3,4-oxadiazoles and 2-substituted-1,3,4-thiadiazoles (16-18) by their reaction with phosphorous oxychloride and phosphorous pentasulphide respectively. The reaction of acid hydrazide (6) with the esters (1,2) in presence of phosphoric acid gave 2,5-disubtituted-1,3,4-oxadiazoles (19,20). The structure of the synthesized compounds were established by the physical and spectral methods.The synthesized compounds (13-20) were tested against six types of bacteria (Staph. aureus, Bacillus subtilis, Proteus mirabilis, E. coli, K. pneumonia, Pseudomonas aemgioson).