One-Pot Method to Access 1,3,4-Oxadiazol-2(3 <i>H</i> )-ones Using Carbonyldiimidazole

A convenient, metal-free one-pot synthesis has been developed to access 1,3,4-oxadiazol-2(3<i>H</i>)-ones using hydrazines, carboxylic acids, and 1,1'-carbonyldiimidazole (CDI) as an activating agent in the presence of triethylamine (TEA). This method can access the desired heterocycles in moderate to excellent yields in a one-pot transformation from commercially available starting materials, representing a significantly simpler path to access these compounds compared with existing tactics. The substrate scope investigation demonstrated that this method is broadly applicable and scalable.