The reaction was carried out in anhydrous toluene (25 mL) with 3-bromo-5-methoxypyridine (2 g, 10.63 mmol), bis(pinacolato)diboron (4.05 g, 15.98 mmol) and potassium acetate (4.78 g, 42.55 mmol). The reaction system was first degassed with nitrogen. Under nitrogen protection, Pd(dppf)Cl2-DCM (0.87 g, 0.10 mmol) was added to the reaction system and the reaction mixture was subsequently heated to reflux for 2 hours. The reaction process was monitored by thin layer chromatography (TLC). After completion of the reaction, the mixture was cooled to room temperature (25 °C) and filtered through a Celite pad. The filtrate was diluted with ethyl acetate (100 mL), washed sequentially with water and brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give the crude product. The crude product was purified by column chromatography on silica gel (100-200 mesh), and the eluent was a hexane solution of 10% ethyl acetate, and 2.6 g of the target product, 5-methoxy-3-pyridinopinacol borate, was finally obtained. The product was analyzed by LC-MS and the molecular weight was 236 (M+H).
