Indium Trichloride Catalyzed Synthesis of 2-Aryl-3-aminobenzofuran Derivatives by a Three-Component Reaction of Phenols, Arylglyoxal Monohydrates and para-Toluenesulfonamide

A concise and efficient synthetic approach to 2-aryl-3-aminobenzofuran derivatives via an InCl3-catalyzed three-component reaction of arylglyoxal monohydrates, phenols and para-toluenesulfonamide has been developed. The benzofuran derivatives were obtained in good to excellent yields while the formation of (alpha)-diketones as by-products was effectively inhibited. The influences of reaction temperature, solvent and the order of the addition were also investigated.