Synthesis
The general procedure for the synthesis of 4-biphenylboronic acid from 4-bromobiphenyl was as follows: 4-bromobiphenyl (30 g, 0.12 mol) was added to a single-neck flask and the reaction was carried out under argon protection. Tetrahydrofuran (THF) (500 mL) was added and stirred at -78 °C for 10 min. Slowly n-butyllithium (2.5 M in hexane) (77 mL, 0.19 mol) was added and the mixture was stirred at -78 °C for 1 hour. Subsequently, dimethyl borate (21.9 mL, 0.19 mol) was added at -78 °C and stirring was continued at -78 °C for 30 min, then brought to room temperature and stirred for 4 hours. After completion of the reaction, extraction was carried out with distilled water and ethyl acetate (EA) and the organic layer was dried with anhydrous magnesium sulfate (MgSO4). The solvent was removed using a rotary evaporator. Finally, pure 4-biphenylboronic acid (21 g, 84% yield) was isolated by column chromatography using hexane and ethyl acetate (EA) as eluents.
References
[1] Patent: WO2011/105700, 2011, A1. Location in patent: Page/Page column 18; 19; 21; 22
[2] Angewandte Chemie - International Edition, 2006, vol. 45, # 9, p. 1404 - 1408
[3] Tetrahedron, 2007, vol. 63, # 20, p. 4297 - 4303
[4] Journal of Organic Chemistry, 2011, vol. 76, # 4, p. 1013 - 1030
[5] Journal of the Chemical Society [Section] C: Organic, 1966, p. 566 - 571
