4-(TRIMETHYLSILYL)PHENYLBORONIC ACID

6999-03-7

17865-11-1

General procedure for the synthesis of 4-trimethylsilylphenylboronic acid from 1-bromo-4-trimethylsilylbenzene: 1-bromo-4-(trimethylsilyl)benzene (25 g, 0.10 mol) was placed in a 1-bulb flask and operated under argon protection. After addition of tetrahydrofuran (500 mL), the reaction mixture was cooled to -78 °C and stirred for 10 min. Slowly n-butyllithium (2.5 M hexane solution, 43.6 mL, 0.10 mol) was added dropwise and stirring was continued for 1 hour and 30 minutes at a maintained temperature of -78 °C. Subsequently, trimethyl borate (13.6 mL, 0.11 mol) was added at the same temperature. The reaction mixture was stirred at -78 °C for 30 minutes and then gradually warmed up to room temperature and continued stirring for 4 hours. After completion of the reaction, extraction was carried out with distilled water and ethyl acetate. The organic layer was dried with anhydrous magnesium sulfate and the solvent was subsequently removed by rotary evaporator. Finally, the target product 4-trimethylsilylphenylboronic acid (18 g, 85% yield) was purified by column chromatography using hexane and ethyl acetate as eluents.