Tributyl borate → (1-Isopropyl-1H-pyrazol-5-yl)boronic acid

Temperatur

0 °C

To a solution of isopropylpyrazole (5.0 g, 45.5 mmol) in THF (100 mL) was added n-butyl lithium (31 mL, 50 mmol, 1.6 M in hexane) at −78° C. The mixture was kept stirring at the same temperature for 30 min. and was allowed to warm to 0° C. and stirred for another 30 min. Before adding tri-n-butyl borate (12.6 g, 55 mmol) as one portion, the reaction mixture was cooled to −78° C. After addition, the mixture was stirred at −78° C. for 1 h. and was allowed to warm to r.t. slowly and stirred overnight. The reaction mixture was quenched by saturated ammonium chloride. The organic phase was separated and the aqueous phase was extracted with ethyl ether (50 mL×2). The combined organic phase was dried over anhydrous sodium sulfate. Solvent was removed to afford 1-isopropyl-1H-pyrazole-5-boronic acid as a viscous oil (5.7 g).

1. stirringstirred for another 30 min
2. temperaturethe reaction mixture was cooled to −78° C
3. additionAfter addition
4. stirringthe mixture was stirred at −78° C. for 1 h.
5. temperatureto warm to r.t. slowly
6. stirringstirred overnight
7. customThe reaction mixture was quenched by saturated ammonium chloride
8. customThe organic phase was separated
9. extractionthe aqueous phase was extracted with ethyl ether (50 mL×2)
10. dry with materialThe combined organic phase was dried over anhydrous sodium sulfate
11. customSolvent was removed

ORD-Eintrag

ord-29eb2be031974ebba7ced0d553b133cc

Quelldatensatz

uspto-grants-2013_05

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08440673B2