Synthesis
4) Synthesis of 2-chloro-5-methoxypyridine: 2-chloro-5-hydroxypyridine (1.30 g) and iodomethane (1.25 mL) were dissolved in N,N-dimethylformamide (26 mL) under nitrogen protection. Subsequently, a methanolic solution of 28% sodium methanol (2.0 mL) was added slowly and dropwise to this solution. The reaction mixture was stirred at room temperature for 1.5 hours. Upon completion of the reaction, the mixture was extracted by adding saturated aqueous ammonium chloride solution and ethyl acetate to the mixture. After separation of the organic phase, it was washed with saturated brine and dried with anhydrous magnesium sulfate. After filtration to remove the desiccant, the solvent was removed by concentration under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: hexane-ethyl acetate gradient) to afford 2-chloro-5-methoxypyridine (1.40 g, 98% yield) as a white solid. The product was confirmed by 1H-NMR (400 MHz, CDCl3): δ 3.85 (3H, s), 7.17-7.25 (2H, m), 8.05 (1H, d, J = 2.9 Hz). LC-MS analysis showed m/z: 144 ([M+H]+).
References
[1] Patent: EP1698626, 2006, A1. Location in patent: Page/Page column 24
[2] Patent: US2010/240634, 2010, A1. Location in patent: Page/Page column 74
[3] European Journal of Inorganic Chemistry, 2015, vol. 2015, # 28, p. 4666 - 4677
[4] Journal of Medicinal Chemistry, 2014, vol. 57, # 6, p. 2462 - 2471
[5] Chemische Berichte, 1992, vol. 125, # 5, p. 1131 - 1140
