The suspension of 5-bromo-3-fluoro-2-hydroxypyridine (10.0 g) in phosphoric acid chloride (50 mL) was heated at 150 °C for 4 hours. The mixture was poured onto ice, and the pH of the resulting mixture was adjusted to 10 by adding potassium carbonate. The mixture was then extracted with dichloromethane. The organic extract was dried over anhydrous magnesium sulfate, filtered, and then concentrated under vacuum to obtain the target product.
Figure 2: Synthetic route of 5-Bromo-2-chloro-3-fluoropyridine
