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 comp...