反应详情

温度

-20 °C

A solution of 2,2,6,6-tetramethylpiperidine (3.10 ml, 18.4 mmol) in THF (80 ml) was cooled to −20° C., then treated with a 2.5 M solution of butyllithium in hexanes (7.03 ml, 17.6 mmol). After stirring at −20° C. for 10 min, the mixture was cooled to −78° C. and treated with a solution of 4-(2,6-difluorophenyl)pyridine (3.20 g, 16.7 mmol) in THF (20 ml). The mixture was stirred at −78° C. for 1.5 h before adding trimethyl borate (3.78 ml, 33.5 mmol). The mixture was allowed to warm to room temperature before adding 5 N aqueous HCl (20 ml). After stirring for 12 h, the solvent was removed in vacuo and the residue was partitioned between 1 N aqueous HCl (100 ml) and diethyl ether (100 ml). The organic layer was then extracted with 1 N aqueous NaOH and the aqueous layer was acidified to pH 8 with 5 N aqueous HCl. The resulting solid was collected by filtration, washed with water and dried to afford 3.20 g (81%) of 2,4-difluoro-3-(pyridin-4-yl)benzeneboronic acid as a white solid: MS (ES+) m/z 235 [M+H]+.

1. temperaturethe mixture was cooled to −78° C.
2. stirringThe mixture was stirred at −78° C. for 1.5 h
3. temperatureto warm to room temperature
4. stirringAfter stirring for 12 h
5. customthe solvent was removed in vacuo
6. customthe residue was partitioned between 1 N aqueous HCl (100 ml) and diethyl ether (100 ml)
7. extractionThe organic layer was then extracted with 1 N aqueous NaOH
8. filtrationThe resulting solid was collected by filtration
9. washwashed with water
10. customdried