1H‐NMR spectra of pyrazino [2,3‐f] quinoxalines and 5,6‐diaminoquinoxalines

The NMR spectra of 2,3- and 2,3,8,9-substituted pyrazino [2,3-f] quinoxalines are described. Unambiguous deuteriation of 5,6-diaminoquinoxalines allowed the assignment of the 7- and β-protons; changes in solvent induce inversions in the peak positions.