Fully substituted 1,3,4-oxadiazole derivatives were obtained in a one-pot three-component reaction of N-isocyaniminotriphenylphosphorane, biacetyl, and (E)-cinnamic acids in dichloromethane under ultrasound irradiation. This rapid method produced the products in short reaction times (16-27min) and excellent yields (91-97%).
The Reaction of <i>N</i>-Isocyaniminotriphenylphosphorane With Biacetyl in the Presence of <i>(E)</i>-Cinnamic Acids: Synthesis of Fully Substituted 1,3,4-Oxadiazole Derivatives via Intramolecular <i>AZA</i>-Wittig Reactions of in Situ Generated Iminophosphoranes
Reaction of N-isocyaniminotriphenylphosphorane with biacetyl in the presence of (E)-cinnamic acids proceeds smoothly at room temperature and under neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and straightforward under mild conditions and no side reactions are observed.