Synthesis
The general procedure for the synthesis of 5-bromo-3-fluoro-2-pyridinecarboxylic acid from 5-bromo-3-fluoro-2-pyridinecarbonitrile was as follows: 5-bromo-3-fluoro-2-pyridinecarbonitrile (21.0 g, 100 mmol) was mixed with concentrated hydrochloric acid (200 mL), and the reaction was carried out at reflux for 4 hours at 140 °C. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently poured into ice water. The precipitated solid was collected by vacuum filtration and dried to afford the target product 5-bromo-3-fluoropyridine-2-carboxylic acid (18.3 g). The structure of the product was confirmed by nuclear magnetic resonance hydrogen spectroscopy (1H NMR, d6-DMSO, 400 MHz) and nuclear magnetic resonance fluorine spectroscopy (19F NMR, d6-DMSO, 300 MHz) with the following data: 1H NMR δ 13.76 (s, 1H), 8.64 (s, 1H), 8.33-8.36 (dd, 1H); 19F NMR δ - 113.70 (d, 1F).
References
[1] Patent: WO2009/36996, 2009, A2. Location in patent: Page/Page column 105
[2] Patent: WO2017/174449, 2017, A1. Location in patent: Page/Page column 89; 90
