Using 2-hydroxy-5-bromopyridine (SM1, 0.1 g, 0.57 mmol) and pinacol ester of bisboronic acid (SM2, 0.88 g, 3.45 mmol) as raw materials, under argon protection, SM1, SM2, tricyclohexylphosphine (0.032 g, 0.114 mmol), Pd2(dba)3 (0.052 g, 0.057 mmol) and KOAc (0.17 g, 1.71 mmol) were dissolved in dioxane (10 mL). The reaction mixture was transferred to a sealed tube and the reaction was stirred at 110 °C overnight. The progress of the reaction was monitored by LC-MS and after confirming complete consumption of the feedstock, the solvent was removed under reduced pressure. The residue was diluted with brine and extracted with EtOAc. The organic phases were combined, dried over anhydrous Na2SO4 and concentrated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography (eluent: 50% EA/PE) to afford the target compound 2-hydroxypyridine-5-boronic acid pinacol ester (Compound 3, 0.08 g, 64%) as a black liquid.
