Synthesis
2-Methoxypyridin-3-amine (39.4 g) was dissolved in N,N-dimethylformamide (200 mL) and the solution was cooled to -30 °C. A solution of N,N-dimethylformamide (100 mL) of N-bromosuccinimide (62.1 g) was slowly added dropwise with stirring. After the dropwise addition, the reaction was continued with stirring for 30 minutes. Subsequently, the reaction mixture was poured into water and extracted with chloroform. The organic layers were combined and washed sequentially with saturated sodium sulfite solution, water and brine. The organic layer was dried with anhydrous sodium sulfate, filtered and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent ratio: hexane:ethyl acetate=9:1→4:1) to afford 6-bromo-2-methoxypyridin-3-amine as a yellow powder (51.9 g, 80% yield). The structure of the product was confirmed by 1H NMR (300 MHz, CDCl3) and mass spectrometry: 1H NMR δppm 3.64-3.84 (m, 2H), 3.98 (s, 3H), 6.78 (dd, J=7.9,1.0 Hz, 1H), 6.87 (d, J=7.9 Hz, 1H); MS (+): 203 [M+H]+.
References
[1] Patent: US2011/237791, 2011, A1. Location in patent: Page/Page column 64
[2] Patent: WO2018/30550, 2018, A1. Location in patent: Paragraph 0648
