Synthesis
In a dry reaction vessel, (3-bromophenyl)trimethylsilane (9.65 g, 42 mmol) was dissolved in ether (200 cm3) and cooled in a dry ice/acetone bath to -78°C. Under stirring, tert-butyllithium (28 cm3, 1.7 M in pentane) was slowly added, keeping the reaction temperature below -70°C. After addition, the reaction was continued with stirring for 30 min. Subsequently, trimethyl borate (20 cm3, 170 mmol) was slowly added and gradually warmed to room temperature and the reaction was stirred for 16 hours. After completion of the reaction, 3M aqueous hydrochloric acid solution (20 cm3) was added and stirring was continued for 2 hours. Water (200 cm3) was added to dilute the reaction mixture and the organic and aqueous layers were separated. The aqueous layer was extracted with ether (3 x 30 cm3) and all organic phases were combined. The organic phase was washed with brine (300 cm3) and dried over anhydrous magnesium sulfate. After filtration, the solvent was removed by concentration under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography using petroleum ether and ethyl ether sequentially as eluents. The fraction containing the target product was collected and concentrated under reduced pressure to give 3-(trimethylsilyl)phenylboronic acid (7.04 g, 86% yield) as a brown solid.
