General procedure for the synthesis of methyl imidazo[1,2-a]pyridine-7-carboxylate from methyl 2-aminoisonicotinate and bromoacetaldehyde diethyl acetal: A mixture of 2-bromo-1,1-diethoxyethane (6.20 mL, 41.2 mmol) and 35% aqueous HCl (0.82 mL, 26.8 mmol) in water (68 mL) was stirred for 2.5 hours. It was then heated at 80 °C and kept at that temperature and stirred for 1.5 hours. After the reaction mixture was cooled to 20 °C, sodium bicarbonate (NaHCO3, 4.49 g, 53.45 mmol) was added in four portions. Finally, methyl 2-aminoisonicotinate (5 g, 32.86 mmol) was added and the reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, the solid formed was collected by filtration, washed with water and dried in a vacuum oven to afford 5.15 g of methyl imidazo[1,2-a]pyridine-7-carboxylate as a brown solid in 89% yield.LRMS: m/z 177 (M + 1)+; retention time: 1.46 min (Method A).1H NMR (200 MHz, CDCl3) δ ppm : 3.97 (s, 3H), 7.27 (s, 1H), 7.42 (d, J = 6 Hz, 1H), 7.70 (s, 1H), 7.80 (s, 1H), 8.19 (d, J = 6 Hz, 1H), 8.37 (s, 1H).
![Methyl imidazo[1,2-a]pyridine-7-carboxylate](/CAS/GIF/86718-01-6.gif)