Synthesis
Step 1: Synthesis of 5-bromo-4-(trifluoromethyl)pyridin-2-amine
To a stirred solution of 4-(trifluoromethyl)pyridin-2-amine (2.5 g, 15.42 mmol) in dichloromethane (250 mL) was added N-bromosuccinimide (2.74 g, 15.42 mmol) in batches. The reaction was carried out at room temperature and under light protection with continuous stirring for 6 hours. After completion of the reaction, the reaction mixture was diluted with 1N NaOH solution (20 mL) and extracted with dichloromethane (2 x 100 mL). The organic layers were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give the title compound (3.2 g, 86% yield).
1H NMR (400 MHz, CDCl3): δ 8.28 (s, 1H), 6.77 (s, 1H), 4.73 (brs, 2H).
ESI-MS: Calculated: 239.95; Measured: 239.10 [M-H]
References
[1] Patent: WO2017/219800, 2017, A1. Location in patent: Paragraph 00209; 00210
[2] Patent: CN105461714, 2016, A. Location in patent: Paragraph 0367; 0368; 0369
[3] Patent: CN103483345, 2016, B. Location in patent: Paragraph 0131-0134
[4] Patent: CN103694218, 2016, B. Location in patent: Paragraph 0093-0096
[5] Patent: WO2014/169167, 2014, A1. Location in patent: Page/Page column 56
