Various alpha-keto-1,3,4-oxadiazole derivatives were synthesized through a sequential intermolecular dehydrochlorination/intramolecular aza-Wittig reaction of carboxylic acids and imidoyl chloride intermediates, which were generated by isocyanide-Nef reaction of acyl chlorides and (N-isocyanimine) triphenylphosphorane (1) in CH2Cl2 at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.