1Department of Chemistry, University of Zanjan, P O Box 45195-313, Zanjan, Iran
2Department of Chemistry, Payame Noor University, P.O. Box 19395-3697, Tehran, Iran
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.