133427-07-3

14667-47-1

133603-12-0

133427-07-3

Example 1: Synthesis of methyl methylimidazo[1,2-a]pyridine-8-carboxylate (Compound No. 1-1) A 47% aqueous hydrogen bromide solution (2.5 mL, 14.4 mmol) was slowly added to diethoxyethidium bromide (2.0 mL, 13.2 mmol), and the reaction mixture was stirred at 50 °C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, ethanol (7.0 mL) and sodium bicarbonate (1.0 g, 11.9 mmol) were added sequentially, stirred and mixed, and the insoluble material was filtered off. To the filtrate was added methyl 2-aminonicotinate (1.0 g, 6.6 mmol), sodium bicarbonate (2.0 g, 13.8 mmol) and ethanol (7.0 mL), and the mixture was heated to reflux for 4 hours. At the end of the reaction, the mixture was cooled to room temperature, and the pH was adjusted by adding saturated aqueous sodium bicarbonate solution. extraction was carried out with dichloromethane (100 mL×3), and the organic phases were combined, washed with water, dried with anhydrous magnesium sulfate, and concentrated under reduced pressure. The crude product obtained was purified by silica gel column chromatography (eluent: chloroform, followed by chloroform/methanol=9/1) to obtain methyl imidazo[1,2-a]pyridine-8-carboxylate (0.6 g, 55% yield) as yellow crystals, melting point 67-69°C. The product was extracted with dichloromethane (100 mL×3) and dried with water.