Engaging DBFO as a C1N1 “two-atom synthon” in [3 + 2] cycloaddition reaction: synthesis of the energetic material 5-azidotetrazolate 1N-oxide

We report a formal [3 + 2] annulation of dibromoformaloxime (DBFO) and sodium azide for the synthesis of tetrazole-based energetic materials. Several energetic salts were prepared and fully characterized by X-ray diffraction, Raman spectroscopy, multinuclear NMR spectroscopy, elemental analysis, differential scanning calorimetry (DSC) and impact and friction sensitivity testing. The heat of formation of nitrogen-rich salts 8 and 9 was calculated by experiments, and detonation parameters were estimated using the EXPLO5 software. This is the first example of using DBFO as a unique C1N1 “two-atom synthon” in the synthesis of tetrazoles. Furthermore, this reaction not only unlocks a different strategy for 5-azidotetrazole synthesis, but also exploits a new reactivity of DBFO.