The general procedure for the synthesis of 2-methoxypyridine-3-boronic acid from 2-methoxypyridine was as follows: 2-methoxypyridine (23.2 g) and diisopropylamine (1.35 mL) were dissolved in tetrahydrofuran (THF, 223 mL) at -20 °C, and lithium (trimethylsilylmethyl) was slowly added (218 mL, 13.8 wt% hexane solution). After 7 hours of reaction, the lithiation was 84% complete. Maintaining a temperature of -20 °C, triisopropyl borate (40.8 g) was added dropwise over 40 min. Subsequently, the reaction mixture was stirred at room temperature overnight. Upon completion of the reaction, 5% aqueous sodium hydroxide solution (225 mL) was added for hydrolysis. After separation of the aqueous layer, the pH was adjusted with 10% aqueous hydrochloric acid solution to 5. The resulting white precipitate was collected by filtration. After drying, 22.23 g of 2-methoxypyridine-3-boronic acid was obtained in 68% yield.
