Triisopropyl borate → 3,4-Difluorobenzeneboronic acid

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%).

1. additionAfter completion of the addition
2. waitThe reaction flask was kept in a cooling bath for 30 min.
3. customThe solvent was removed
4. dissolutionthe residue was dissolved in ether
5. washwashed with 1N HCl and water
6. dry with materialdried over Na2SO4
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customthe residue was purified by recrystallyzation with CH2Cl2 and hexane

ORD record

ord-3c3de9ee85db42a18bae6de92c23c757

Source dataset

uspto-grants-2013_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08450308B2