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) solution 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 recrystallization 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 recrystallization with CH2Cl2 and hexane

ORD record

ord-1c7c4d7d136f48508fe24f7ec962d548

Source dataset

uspto-grants-2014_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08921359B2