Triisopropyl borate → 3,4-Difluorobenzeneboronic acid

Participants

Reaction Steps

To a stirred solution of 4-bromo-1,2-difluorobenzene (3.5 g, 17.86 mmol) in dry THF was cooled to −78° C., was added a n-BuLi (10.71 mL) slution dropwise. After completion of the addition, the mixture was stirred for 15 min., and triisopropyl borate (6.71 g, 35.71 mmol) was added in one portion. The reaction flask was kept in a cooling bath for 30 min., and warmed to room temperature for 3 hours. The solvent was removed, the residue was dissolved in ether, washed with 1N HCl and water, dried over Na2SO4, filtered, and concentrated in vacuo, the residue was purified by recrystallyzation with CH2Cl2 and hexane to give the pure 3,4-difluorophenylboronic acid (800 mg, 20%).

Provenance & Evidence