one-pot, four-component synthesis of fully substituted 1,3,4-oxadiazole derivatives from n-isocyaniminotriphenylphosphorane (ph3pnnc), a primary amine, a carboxylic acid and cinnamaldehyde

the imine intermediate generated by the addition of primary amine to the cinnamaldehyde is trapped by the n-isocyaniminotriphenylphosphorane (ph3pnnc) and a carboxylic acid, and leads to the formation of the corresponding iminophosphorane intermediate. the 1,3,4-oxadiazole derivatives are formed via intramolecular aza-wittig reaction of the iminophosphorane intermediate. the reactions were completed under neutral conditions at room temperature. the fully substituted 1,3,4-oxadiazole derivatives were produced in high yields. the method offers a mild, simple, and efficient route for the preparation of fully substituted 1,3,4-oxadiazols. the structures of the products were deduced from their ir, 1h nmr, 13c nmr spectra, and mass spectrometry.