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

Participants

Reaction Conditions

Reaction Steps

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).

Provenance & Evidence