Synthesis of 1,2,3,4-tetrazino[5,6-f]benzo 1,2,3,4-tetrazine 1,3,7,9-tetra-N-oxides

[GRAPHICS] The novel heterocyclic system 10 with the phenanthrene type skeleton, in wh ich the benzene ring is annulated with two 1,2,3,4 tetrazine 1,3 di-N-oxide rings, is of considerable interest in the context of the high nitrogen sys tem stability and from a heteroaromaticity standpoint. The step by step syn thetic approach to this system involves treatment of 5 with N2O5, resulting in the first 1,2,3,4 tetrazine 1,3 dioxide ring formation, The following d isplacement of the chlorine atom at the 6-position with ammonia and subsequ ent repeated treatment with N2O5 results in the second 1,2,3,4 tetrazine 1, 3 dioxide ring formation. The structure of 10 was confirmed by a C-13 and N -14 NMR Study.