The general procedure for the synthesis of 3-aminoisonicotinic acid from 3,4-pyridinedicarboximide is as follows:
Step 1: Bromine (1.93 mL, 38.6 mmol) was slowly added to a 10% aqueous sodium hydroxide solution (100 mL) followed by 1H-pyrrolo[3,4-c]pyridine-1,3(2H)-dione (5.20 g, 35.1 mmol) under ice-bath cooling conditions. Next, 10% aqueous sodium hydroxide solution (60 mL) was added to the reaction mixture and the mixture was heated and stirred at 90 °C for 40 min. Upon completion of the reaction, the mixture was cooled to room temperature and the pH was adjusted with 50% sulfuric acid to 3. The precipitated solid was collected by filtration and washed with water to afford 3-aminoisonicotinic acid in the form of a light yellow powder (5.00 g, 100% yield). The product was characterized by 1H-NMR (200 MHz, DMSO-d6): δ 7.46 (1H, d, J = 5.1 Hz), 7.73 (1H, d, J = 5.1 Hz), 8.21 (1H, s).
