Synthesis
Under nitrogen protection, 2,6-dimethoxypyridine (10 g, 71.84 mmol) and N,N-diisopropylethylamine (0.50 mL, 3.59 mmol) were dissolved in dry tetrahydrofuran (200 mL), and cooled to -40°C. The solution of n-butyl lithium (43.10 mL, 86.21 mmol) was added to the solution. At this temperature, n-butyllithium solution (43.10 mL, 86.21 mmol) was added slowly and dropwise. The reaction solution was stirred at -40 °C for 5 min and then slowly warmed to 0 °C and continued to be stirred at this temperature for 3 hours. Subsequently, the reaction solution was cooled again to -40 °C and triisopropyl borate (24.87 mL, 107.76 mmol) was slowly added. After addition, the reaction mixture was brought to room temperature and stirred for 1 hour. Upon completion of the reaction, the reaction was terminated by the addition of water (50 mL), followed by concentration under reduced pressure to remove the organic solvent. To the residue was added 1 M sodium hydroxide solution (100 mL) and the aqueous phase was washed with ethyl acetate (2 x 100 mL). The aqueous phase was adjusted to pH 3 with hydrochloric acid and a solid was precipitated. The solid was collected by filtration and dried to give 2,6-dimethoxypyridine-3-boronic acid (8.10 g, 61% yield). The product was characterized by 1H NMR (DMSO-d6): δ 7.87 (1H, d, J = 7.9 Hz), 6.36 (1H, d, J = 7.9 Hz), 3.90 (3H, s), 3.87 (3H, s).
