Reactions of (N-isocyanimino)triphenylphosphorane with (1R)-(−)-campherchinon in the presence of aromatic carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.

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A simple method has been developed for four-component synthesis of disubstituted 1,3,4-oxadiazoles using (N-isocyanimino)triphenylphosphorane, a primary amine, a carboxylic acid and biacetyl in CH 2 Cl 2 by the Ugi-4CR/aza-Wittig sequence at room temperature in excellent yields.