25813-25-6

Step 36-1: 4-Hydroxypyridine (T96-1, 7.0 g, 74 mmol) was dissolved in carbon tetrachloride (360 mL) at room temperature. Subsequently, N-bromosuccinimide (NBS, 26.2 g, 0.147 mol) was added to this solution. The reaction mixture was to be covered with aluminum foil to avoid light and stirred continuously for 24 h in a dark environment. After completion of the reaction, the reaction mixture was concentrated by distillation under reduced pressure. The resulting residue was sequentially purified by grinding with methanol and acetone to give 4-hydroxy-3,5-dibromopyridine (T96-2, 18.9 g, 100% yield).

[1] Patent: US2010/93720, 2010, A1. Location in patent: Page/Page column 58
[2] Synthesis, 2001, # 14, p. 2175 - 2179
[3] Patent: WO2018/92047, 2018, A1. Location in patent: Page/Page column 94
[4] Patent: EP3351533, 2018, A1. Location in patent: Paragraph 0676; 0677
[5] Patent: JP2018/145180, 2018, A. Location in patent: Paragraph 0633; 0634; 635