1-Acetyl-3-(4-methoxyphenyl)-1H-[1,3,4]oxadiazino[5,6-b]quinoxaline 4-(1-Acetyl-1H-[1,3,4]oxadiazino[5,6-b]quinoxalin-3-yl)phenyl methyl ether AIDS-137954 AIDS137954 NSC643713