Synthesis of biologically active pyridazinoquinoxalines

The 2-(1-methylhydrazino)quinoxaline 4-oxides 9a,b were converted into the pyridazino[3,4-b]-quinoxalines 10a,b,15a,b,22 and 1,2-diazepino[3,4-b]quinoxalines 29a-c, which were further transformed into the 3-substituted 1-methylpyridazino[3,4-b]quinoxalin-4(1H)-ones 5–8.