Synthesis of 2-Aryl Benzoxazoles from Benzoxazoles and α-Ketoic Acids by Photoredox Catalysis

An efficient protocol for the synthesis of 2-aryl benzoxazoles via visible light-initiation has been developed.Compared with the traditional method for the synthesis of arylbenzoxazole, the reaction conditions of this method are mild, and only Eosin Y is needed as photocatalyst without any other metal catalyst.The purification of the desired product is easier because only CO2 is produced as the byproduct.Under the optimal reaction conditions, benzoxazole with different substituents and α-keto acids show very good reactivity and a series of arylbenzoxazoles can be synthesized.