Abstract: Eleven antibiotics quinoxaline-1, 4-dioxides (2α-k) were synthesi/ed according to direct oxidation and Beirut reaction.Detailed UV,IR, NMR data were reported and relevant spectroscopic properties were discussed. EPR studies showed that stable paramagnetic species were formed in the photolytic process of these N-oxides in solution.Well-resolved EPR spectrum was obtained from the photolytic solution of 2,3-cyclobutylenequinoxaline-l,4-dioxide(2g). in chloroform, and the hyperfire splittings of 9.69G(1N), 3.59G(2H), 1.25G(2H) and 0.76G(1H) were determined from the spectrum. This radical was assigned as l-hydroxy-2,3-cyclobutylenequinoxalinyl-4-oxyl(4).The similarities between naphthaquinones and quinoxaline-l,4-dioxides in molecular structure and in properties were also pointed out.

Key words: Antibiotics, Quinoxaline-1,4-dioxides(p), Synthesis, Beirut reaction, Spectroscopic property, Electron paramagnetic resonance spectrum