Hydrochloric Acid → (1-phenyl-1H-pyrazol-5-yl)boronic acid

Temperature

-78 °C

To a solution of 1-phenyl-1H-pyrazole (12.8 g, 88.9 mmol) in THF (355 mL) was dropwise added n-BuLi (1.63 M solution in hexane, 57.2 mL, 93.3 mmol) at −78° C. under N2. The mixture was stirred at −78° C. for 1 h. To the mixture was added B(Oi-Pr)3 (82.0 mL, 355 mmol) at −78° C. The mixture was stirred at −78° C. for 1 h, gradually warmed to room temperature and stirred at room temperature overnight. The pH of the mixture was adjusted to 5 with 1 M HCl aqueous solution. The mixture was concentrated in vacuo, extracted with EtOAc, washed with brine, dried over Na2SO4, filtered, concentrated in vacuo and crystallized with MeOH/EtOAc/hexane to yield the title compound (12.6 g, 76% yield) as a pale yellow solid: 1H NMR (DMSO-d6, 300 MHz): δ ppm 6.73 (1H, brs), 7.28-7.39 (1H, m), 7.39-7.54 (4H, m), 7.66 (1H, s).

1. customat −78° C.
2. stirringThe mixture was stirred at −78° C. for 1 h
3. temperaturegradually warmed to room temperature
4. stirringstirred at room temperature overnight
5. concentrationThe mixture was concentrated in vacuo
6. extractionextracted with EtOAc
7. washwashed with brine
8. dry with materialdried over Na2SO4
9. filtrationfiltered
10. concentrationconcentrated in vacuo
11. customcrystallized with MeOH/EtOAc/hexane

ORD record

ord-e646437fd42e4d84a29f896ede87edd9

Source dataset

uspto-grants-2013_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08513251B2