697739-12-1

64-18-6

697739-11-0

108-24-7

697739-12-1

Acetic anhydride (38.21 mL, 405 mmol) and formic acid (15.28 mL, 405 mmol) were mixed and reacted at 60 °C for 2 h and subsequently cooled to room temperature. To this reaction mixture was added ethyl 2-(aminomethyl)-3-pyridinecarboxylate hydrochloride (17.55 g, 81 mmol), and the resulting mixture was stirred at room temperature for 1 hour and then heated at 35°C for 3 hours. After completion of the reaction, the mixture was cooled to 5 °C and neutralized with 0.88 aqueous ammonia solution, followed by extraction with dichloromethane (3×). The combined dichloromethane layers were washed sequentially with water, saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered and concentrated. The residue was purified by silica gel column chromatography to afford ethyl imidazo[1,5-a]pyridine-8-carboxylate (8.67 g, 56% yield) using dichloromethane solution containing 2% methanol (containing 0.5% ammonia) as eluent.