Synthesis
Sodium hydride (60% dispersed in mineral oil, 0.644 g, 16.09 mmol) was added batchwise to a solution of N,N-dimethylformamide (DMF, 20 mL) of 6-bromopyridin-3-ol (2.0 g, 11.49 mmol) at room temperature and the reaction mixture was stirred for 30 min at 0 °C. Subsequently, iodoethane (1.858 mL, 22.99 mmol) was slowly added dropwise and the reaction mixture was continued to be stirred at room temperature for 3.5 hours. Upon completion of the reaction, the reaction was quenched by adding water to the mixture and the organic phase was extracted with ethyl acetate. The combined organic layers were washed sequentially with water and saturated saline, dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography (eluent: hexane-ethyl acetate gradient elution) to afford 2-bromo-5-ethoxypyridine (2.32 g, 100% yield). The product was characterized by 1H-NMR (CDCl3): δ 8.03 (1H, d, J = 2.75 Hz), 7.35 (1H, d, J = 8.69 Hz), 7.07 (1H, dd, J = 8.62, 2.97 Hz), 4.05 (2H, q, J = 6.91 Hz), 1.43 (3H, t, J = 6.94 Hz).
References
[1] Patent: EP2752410, 2014, A1. Location in patent: Paragraph 0441-0443
[2] Patent: WO2012/74126, 2012, A1. Location in patent: Page/Page column 335; 336
