Synthesis of di- and tetra-substituted 1,4,5,8-tetra-azaphenanthrenes (pyrazino[2,3-f]quinoxalines)

6-Nitroquinoxalines (I) are aminated by hydroxylamine to 5-amino-6-nitroquinoxalines (II). These are reduced to 5,6-diaminoquinoxalines (III) which condense with appropriate α-dicarbonyl compounds to yield substituted 1,4,5,8-tetra-azaphenanthrenes (IV).