Diazanaphthalene

Diazanaphthalenes are a class of aromatic heterocyclic chemical compounds that have the formula C₈H₆N₂. They consist of a naphthalene double ring in which two of the carbon atoms have been replaced with nitrogen atoms. There are ten positional isomers, which differ by the locations of the nitrogen atoms.

The group consist of two subgroups:

• four benzodiazines with both N atoms in one ring: cinnoline, quinazoline, quinoxaline, and phthalazine
• six naphthyridines with one N atom per ring^[1][2]

Isomers

name	structure	subgroup
1,2-diazanaphthalene (cinnoline)		benzodiazine
2,3-diazanaphthalene (phthalazine)		benzodiazine
1,3-diazanaphthalene (quinazoline)		benzodiazine
1,4-diazanaphthalene (quinoxaline)		benzodiazine
1,8-diazanaphthalene		naphthyridine
1,7-diazanaphthalene		naphthyridine
2,7-diazanaphthalene		naphthyridine
1,6-diazanaphthalene		naphthyridine
1,5-diazanaphthalene		naphthyridine
2,6-diazanaphthalene		naphthyridine

References

1. Desmond J. Brown, Jonathan A. Ellman, Edward C. Taylor: The Chemistry of Heterocyclic Compounds, The Naphthyridines, John Wiley & Sons, 2007.
2. Paudler, William W.; Kress, Thomas J. (1968). "Naphthyridine chemistry. IX. Bromination and animation of the 1,X-naphthyridines". The Journal of Organic Chemistry. 33 (4): 1384–1387. doi:10.1021/jo01268a018.