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

Temperatur

-78 °C

To a solution of 1-methyl-1H-pyrazole (110 g, 1.34 mol) in anhydrous tetrahydrofuran (2 L), with stirring, was added drop-wise n-butyllithium (2.5 M, 590 mL, 1.47 mol) at −78° C. After completion of the addition, the mixture was stirred for 1.5 hours at −78° C. Then triisopropyl borate (277 g, 1.47 mol) was added and the mixture was gradually warmed to room temperature and stirred overnight. Saturated aqueous ammonium chloride solution (1 L) was added drop-wise, while keeping the temperature of the reaction mixture below 10° C. The resulting mixture was acidified to a pH of approximately 6 with 1 N aqueous hydrochloric acid. The organic phase was separated and the aqueous phase was extracted with ethyl acetate (3×1 L). The combined organic layers were washed with saturated aqueous sodium chloride solution, dried over sodium sulfate, and filtered; and the solvent was removed under reduced pressure. The residue was washed with petroleum ether (3×300 mL) and the resulting solid was dried under vacuum to afford the product as a white solid. Yield: 157 g, 1.25 mol, 93%. 1H NMR (400 MHz, DMSO-d6) δ 3.97 (s, 3H), 6.72-6.74 (m, 1H), 7.34-7.36 (m, 1H), 8.35 (br s, 2H).

1. additionAfter completion of the addition
2. temperaturethe mixture was gradually warmed to room temperature
3. stirringstirred overnight
4. customthe temperature of the reaction mixture below 10° C
5. customThe organic phase was separated
6. extractionthe aqueous phase was extracted with ethyl acetate (3×1 L)
7. washThe combined organic layers were washed with saturated aqueous sodium chloride solution
8. dry with materialdried over sodium sulfate
9. filtrationfiltered
10. customand the solvent was removed under reduced pressure
11. washThe residue was washed with petroleum ether (3×300 mL)
12. customthe resulting solid was dried under vacuum

ORD-Eintrag

ord-56fae7c279d749159493ca883e106b31

Quelldatensatz

uspto-grants-2014_09

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08829010B2