514797-96-7

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514797-96-7

Example 6 (a) Synthesis of 5-chloro-3-fluoro-2-hydroxypyridine: Sodium hydroxide (101 g, 2.5 mol) was dissolved in water (500 mL) and liquid 5-chloro-2,3-difluoropyridine (101 g, 0.68 mol) was slowly added to this solution. The reaction mixture was heated to reflux and held overnight. After completion of the reaction, it was cooled to room temperature and the mixture was filtered through a diatomaceous earth pad. Subsequently, the pH of the filtrate was adjusted with concentrated hydrochloric acid to 1. The precipitated solid was collected by filtration and dissolved in ethyl acetate. The combined organic phases were dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. 2-Hydroxy-3-fluoro-5-chloropyridine was obtained as a white solid (78 g, 78% yield), and the product could be used in subsequent reactions without further purification. The structure of the product was confirmed by 1H NMR.