(4'-Pentyl[1,1'-biphenyl]-4-yl)-boronic acid

63619-59-0

121554-18-5

General procedure for the synthesis of 4-pentylbiphenylboronic acid from 4'-bromo-4-pentylbiphenyl: 4'-bromo-4-pentylbiphenyl (3 g, 9.9 mmol) was added in a single addition to magnesium shavings (0.27 g, 11.1 mmol) in an iodine-catalyzed reaction using tetrahydrofuran (40 mL) as solvent. The reaction mixture was heated at reflux for 3 h and subsequently cooled to -78 °C and trimethyl borate (2.06 g, 19.8 mmol) was added slowly and dropwise. The reaction system was gradually warmed to room temperature over 1 h, then acidified with 2 M hydrochloric acid (50 mL) and extracted with ether (3 x 50 mL). The combined ether extracts were back-extracted with 1 M sodium hydroxide solution (100 mL). The aqueous phase was acidified with concentrated hydrochloric acid and extracted again with ether (3×50 mL), the organic phase was dried with anhydrous magnesium sulfate, and the solvent was removed by concentration under reduced pressure to obtain 4-pentylbiphenylboronic acid (2.07 g, 78% yield), the product was an off-white powder.