[Synthesis]
General procedure for the synthesis of 6-methoxyimidazo[1,2-a]pyridine from methanol and 6-iodoimidazo[1,2-a]pyridine: In a solvent mixture of toluene (10 mL) and methanol (5 mL), 6-iodoimidazo[1,2-a]pyridine (1.0 g, 4.1 mmol) was added. After allowing to dissolve, copper(I) iodide (160 mg, 0.84 mmol), 1,10-phenanthroline (300 mg, 1.66 mmol) and cesium carbonate (3 g, 9 mmol) were added sequentially. The reaction mixture was stirred and reacted at 120 °C overnight. After completion of the reaction, it was cooled to room temperature and extracted by adding water and ethyl acetate. The organic layer was separated, washed sequentially with water and saturated saline and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure, and the resulting crude product was purified by silica gel column chromatography (eluent ratio: hexane:ethyl acetate:methanol, 50:50:0 → 0:100:0 → 0:95:5, v/v) to afford the target compound 6-methoxyimidazo[1,2-a]pyridine (360 mg, 59% yield).1H-NMR (CDCl3) δ: 3.82 (3H s), 6.96 (1H, dd, J = 9.6, 2.3 Hz), 7.50 (1H, d, J = 9.6 Hz), 7.52 (1H, s), 7.57 (1H, s), 7.66 (1H, d, J = 2.3 Hz). |