The general procedure for the synthesis of 2-pyridineboronic acid from 2-bromopyridine and triisopropyl borate was as follows: 1.58 g (10 mmol) of 2-bromopyridine and 3.76 g (20 mmol) of triisopropyl borate were dissolved in a solvent mixture of 14 mL of anhydrous toluene and 7 mL of THF, stirred and cooled at -30 °C. Under nitrogen protection, 6.25 mL (10 mmol) of 1.6 M n-butyllithium hexane solution was added slowly dropwise with a syringe. After the dropwise addition, the reaction mixture was continued to be stirred at -30 °C for 3 h. Subsequently, it was brought to room temperature and stirred for another 3 h. The completion of the reaction was monitored by TLC. 1 mL of concentrated hydrochloric acid was slowly added to the reaction mixture and stirred for 1 hr at room temperature before the mixture was poured into 200 mL of ice water. The pH was adjusted to 8 with saturated sodium bicarbonate solution, stirred, and extracted three times with 50 mL of dichloromethane. The organic phases were combined, washed with 100 mL of 5% brine and dried over anhydrous sodium sulfate. The desiccant was removed by filtration, the filtrate was concentrated to dryness by rotary evaporator, and the residue was purified by silica gel column chromatography to give 1.00 g of 2-pyridineboronic acid in 81% yield.
