One-Pot Synthesis of Oxazoles by the Reaction of Carboxylic Acids, Benzoin, and Ammonium Acetate

A green protocol for the preparation of 4,5-diphenyl-2(R)-oxazoles from the reaction of benzoin, carboxylic acids, and ammonium acetate is described. This process is accomplished without the use of any organic solvent or catalyst. By this method, aromatic acids carrying electron-withdrawing groups reacted faster with higher yields. However, the reaction has generality for those with electron-donating groups and ortho-substituted ones. Even aliphatic carboxylic acids also provided the corresponding oxazoles in appropriate yields. Extraction of the product is simply achieved by the addition of water to the reaction mixture.