The general procedure for the synthesis of 2-(2-(difluoromethyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolanes from 1-bromo-2-difluoromethylbenzene (19.8 g, 95.7 mmol) and isopropanol pinacol borate was as follows: 1-bromo-2-difluoromethylbenzene was dissolved under nitrogen protection in dry tetrahydrofuran (THF, 200 mL) in tetrahydrofuran (THF, 200 mL) and cooled to -78 °C. A hexane solution (42 mL, 105 mmol) of 2.5 M n-butyllithium (n-BuLi) was slowly added. After addition, the reaction mixture was continued to stir at -78 °C for 1 hour. Subsequently, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (25 mL, 123 mmol) was added and slowly warmed to room temperature. After stirring overnight at room temperature and under nitrogen protection, the reaction mixture was poured into water (400 mL). The organic layer was separated by extraction with ethyl acetate (300 mL). The aqueous layer was extracted twice with ethyl acetate (150 mL and 50 mL). The organic layers were combined, washed with water, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated to dryness under reduced pressure. The brown oil obtained (21 g) was purified by ball-ball distillation (3 x 10^-3 mbar, 90-95 °C) to afford 2-(2-difluoromethylphenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane (14.4 g, 59% yield) as a light yellow oil.
