Synthesis
4.1.7 Synthesis of 5-bromopyridine-2-carboxylic acid (11): In a 250 mL three-necked flask assembled with a stirrer, thermometer, and condenser tube, add 150 mL of water and 5-bromo-2-methylpyridine (10) (6.0 g, 35 mmol). After turning on the stirring and heating to 80 °C, potassium permanganate (KMnO4) (24.8 g, 157 mmol) was added in three batches at 1 h intervals. The reaction temperature was maintained at 80 °C and stirring was continued for 3-4 hours. Upon completion of the reaction, filtration was carried out to obtain a clarified filtrate. The pH of the filtrate was adjusted to 4-5 with concentrated hydrochloric acid, at which point a white solid precipitated. The filtrate was filtered to collect a small amount of product (11). The filtrate was concentrated under vacuum and an appropriate amount of ethanol was added to the residue to dissolve compound (11), at which time a large amount of white solid precipitated, the filtrate was again withdrawn and the solid discarded. Finally, the filtrate was concentrated under vacuum to give a light yellow solid product (11) (3.0 g, 39% yield).
References
[1] Bioorganic and Medicinal Chemistry, 2015, vol. 23, # 13, p. 3228 - 3236
[2] Journal fuer Praktische Chemie (Leipzig), 1932, vol. <2> 133, p. 36,49
[3] Heterocycles, 1981, vol. 15, # 1, p. 213 - 223
[4] Synthesis, 2003, # 4, p. 551 - 554
[5] Patent: US2005/113374, 2005, A1. Location in patent: Page/Page column 8
