Synthesis
Under nitrogen protection, 2-chloro-4-aminopyridine (15 g, 0.116 mol, 1.0 equiv) was dissolved in acetonitrile (200 mL) and heated to 70 °C in an oil bath. N-iodosuccinimide (NIS, 33 g, 0.139 mol, 1.2 equiv) was slowly added and the reaction mixture was stirred at 70 °C for 16 hours. After completion of the reaction, the reaction was cooled to room temperature and the pH of the reaction system was adjusted to 9-10 by addition of saturated aqueous sodium carbonate. the reaction mixture was extracted with ethyl acetate (500 mL) and the organic phase was separated. The organic phase was washed twice with saturated saline (100 mL) and dried with anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure to give 2-chloro-5-iodo-4-pyridinamine (23 g, 78.1% yield).
References
[1] Patent: CN105622638, 2016, A. Location in patent: Paragraph 0194
[2] Patent: WO2015/38417, 2015, A1. Location in patent: Page/Page column 73; 74
[3] Journal of Medicinal Chemistry, 2012, vol. 55, # 22, p. 10229 - 10240
[4] Journal of Medicinal Chemistry, 2016, vol. 59, # 11, p. 5221 - 5237
[5] Patent: WO2014/207260, 2014, A1. Location in patent: Page/Page column 77
