Synthesis and antibacterial activity of 2-cinnamyl-5-substituted-1, 3, 4-oxadiazole, 1, 3, 4-thiadiazoles and 5-cinnamyl-3-substituted-1, 2, 4-triazoles

Abstract EN

In this work the synthesis of 2-cinnamyl-5-substituted-1,3,4-oxadiazoles, 1,3,4-thiadiazole and 5-cinnamyl-3-substituted-1,2,4-triazoles was achieved.

Ethyl cinnamate was refluxed with hydrazine hydrate in ethanol to give the corresponding acid hydrazides, which then treated with ammonium thiocyanate to give thiosemicarbazide.

The thiosemicarbazide cyclized to 5-amino-2-cinnamyl-1,3,4-thiadiazole and 5-cinnamyl-1,2,4-triazole-3-thiol with sulfuric acid and sodium hydroxide solution respectively.

The acid hydrazide was treated with substituted benzaldehyde to yield hydrazone, which then treated with PbO2 to give 2-cinnamyl-5-aryl/phenyl-1,3,4-oxadiazoles.

2-Cinnamyl-1,3,4-oxadiazole was obtained from acid hydrazide by its reaction with formic acid followed by PbO2.

Acid hydrazide was converted to substituted thiosemicarbazode by the reaction with phenyl isothiocyanate.

The synthesized conpounds (1, 2, 5, 6, 9, 11 and 13) were tested against Escherichia coli, Staphylococcus aureus, Salmonella typhi and Pseudomonas.

The structures of the synthesized compounds were established by physical and spectral means.