A Safer Synthesis of the Explosive Precursors 4‑Aminofurazan-3-Carboxylic Acid and its Ethyl Ester Derivative

A safe and efficient one-pot synthesis of 4-aminofurazan-3-carboxylic acid and its hydrogen chloride gas-free conversion to the ethyl ester derivative are described. Previous syntheses of these intermediates were plagued with mischaracterization issues, low yields, and/or dangerous exothermic profiles. The safe scale-up of these materials not only provides benefits to the energetic materials community but may also be of importance to the pharmaceutical and agrochemicals industries.