Ligand-free synthesis of 2-aminoarylbenzoxazoles via copper-catalyzed C[sbnd]N/C[sbnd]O coupling

Abstract

A copper-catalyzed CN/CO coupling has been developed for synthesis of 2-aminoarylbenzoxazole derivatives. The protocol uses readily available 2-halo-N-(2-halophenyl)benzamides and amines as the starting materials, and the corresponding 2-aminoarylbenzoxazoles were obtained in good to excellent yields. Both aromatic and aliphatic amines were tolerated, and no ligand was used in this reaction. Gram-scale synthesis was also carried out successfully. These results showed the potential synthetic value of this new reaction in organic synthesis.