2-Hydroxypyridine-5-boronic acid pinacol ester (300 mg, 1.357 mmol), sodium difluorochloroacetate (320 mg, 2.036 mmol), and acetonitrile (5 mL) were sequentially added to a sealed reaction tube to form a suspension. The reaction mixture was heated to 80 °C and continuously stirred overnight. After completion of the reaction, the mixture was cooled to room temperature, diluted with ethyl acetate and washed sequentially with saturated aqueous sodium bicarbonate and brine. The organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated. The target compound 2-(difluoromethoxy)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (197 mg, 53% yield) was purified by rapid chromatography on silica gel column (eluent: dichloromethane/methanol, 95/5). Mass spectrometry result: m/z 272.8 [M + H]+, retention time (Method 6): 3.12 min.
