Synthesis of Some Substituted 1,3,4-Oxadiazoles from Hydrazones

ABSTRACT In this paper the synthesis of some 2-(3-pyridyl)-5-aryl-1,3,4-oxadiazoles from hydrazones is reported. Nicotinic acid was converted to ethyl nicotinate (1) by its reaction with thionyl chloride and the resultant acid chloride was treated with absolute ethanol, the ethyl nicotinates was treated with hydrazine hydrate in ethanol to give the corresponding acid hydrazide (2). The acid hydrazide was treated with benzaldehyde or substituted benzaldehyde to give the hydrazones (3-8). The hydrazones were cyclized to 2-(3-pyridyl)-5-aryl-1,3,4-oxadiazoles (4-14) by their reaction with lead oxide. The structure of the synthesised compounds were confirmed by physical and spectral methods.