Microwave-assisted Synthesis of 6-{(5-Aryl-1,3,4-oxadiazol-2-yl)methyl}-6H-indolo[2,3-b]quinoxalines

An efficient and convenient synthesis of a new series of 2-{(6H-indolo[2,3-b]quinoxalin-6-yl)methyl}-5-aryl-1,3,4-oxadiazoles from readily available 1,2-diaminobenzene and isatins under microwave irradiation conditions was disclosed. The 6-{(5-aryl-1,3,4-oxadiazol-2-yl)methyl}-6H-indolo[2,3-b]quinoxalines were also prepared by the thermal cyclo-condensation reaction of 2-(6H-indolo[2,3-b]quinoxalin-6-yl)acetohydrazides with carboxylic acids in refluxing POCl3. The microwave-assisted synthesis was rapid and resulted in higher yield of the products at lower operating temperature with reduced waste generation in comparison with the thermal reaction protocol.