A Mild and Efficient One‐Pot Preparation of 1,2,4‐Oxadiazoles from Nitriles and Carboxylic Acids Using Vilsmeier Reagent

Abstract A one‐pot synthesis of 1,2,4‐oxadiazoles has been achieved from the corresponding amidoximes and carboxylic acids or from nitriles, hydroxylamine and carboxylic acids, employing the OH activation property of the Vilsmeier reagent. The precursor O ‐acylamidoxime could be derived in situ which underwent an intramolecular cyclization in the presence of Vilsmeier reagent to afford 1,2,4‐oxadiazole. The products were simply obtained in good to excellent yields under mild condition and compatible with a range of functional groups. Utilization of easy workup and purification of products make it very interesting.