General procedure for the synthesis of (2-fluoro-6-methylphenyl)boronic acid from 2-bromo-1-fluoro-3-methylbenzene: 2-bromo-1-fluoro-3-methylbenzene (300 mg, 1.59 mmol) was dissolved in anhydrous ether (3 mL), and triisopropyl borate (6.2 mL, 26.7 mmol) was added. The reaction mixture was cooled to -78 °C under argon protection. A tert-butyl lithium solution (1.7 M in pentane, 2.2 mL, 3.74 mmol) was added slowly and dropwise. The reaction system was then warmed to -10 °C and stirred at this temperature for 30 min. Upon completion of the reaction, 5N hydrochloric acid (2 mL) was added and stirring was continued for 30 minutes at room temperature. The reaction mixture was extracted twice with diisopropyl ether and the organic layers were combined and alkalized with 2N sodium hydroxide solution. The aqueous phase was adjusted to pH 1 with hydrochloric acid and extracted twice with ether. The organic layers were combined, washed with saturated brine and dried over anhydrous sodium sulfate. The organic layer was concentrated under reduced pressure to give (2-fluoro-6-methylphenyl)boronic acid (117 mg, 43% yield) as a white solid. lRMS (m/z): 155 (M + 1)+.
