Three nitrogen-rich heterocyclic compounds containing the diamino-pyrimidine mono-N-oxide moiety were synthesized via mild oxidation reactions. Oxidation of the furazano-pyrimidine compound (1) with a mixture of trifluoroacetic anhydride (TFAA) and hydrogen peroxide (50%) gave the nitrate salt (3). All of the compounds were characterized by NMR spectra, elemental analysis, and single-crystal X-ray diffraction. They show high thermal stability and good detonation performance as well as low sensitivity.