General procedure for the synthesis of 5-amino-2-pyridinecarboxylic acid from 3-amino-6-cyanopyridine: preparation of intermediate 76.5-aminopyridine-2-carboxylic acid. 5-Amino-2-cyanopyridine (10.0 g, 83.9 mmol) was dissolved in sulfuric acid (50 mL), and the resulting solution was transferred to a high-pressure vessel and reacted at 90 °C for 2 hours. Subsequently, water (100 mL) was added to the reaction mixture and continued to be heated to 100 °C for 2 hours. Upon completion of the reaction, the orange reaction solution was slowly poured into the ice-water mixture with continuous stirring for 15 minutes, at which time a light beige solid precipitated. The solid product was collected by filtration, washed with cold water and subsequently dried under vacuum overnight to afford the target compound 5-amino-2-pyridinecarboxylic acid (11.7 g, 100% yield).LRMS (m/z): 139 (M + 1)+.
