Triisopropyl borate → (4-Fluoro-3-methylphenyl)boronic acid

Temperatur

-78 °C

5-Bromo-2-fluorotoluene (6 g, 31.7 mmol) was dissolved in dry THF (50 mL) and cooled to −78° C. under N2. n-BuLi (14 mL, 2.5M solution in THF) was added slowly using a dry syringe. Cloudiness appeared. The reaction was stirred for 40 minutes at −78° C. Triisopropyl borate (22 mL, 95 mmol) was slowly added while stirring. The reaction was allowed to warm to room temperature. Stirring continued for an additional 2 hours. A pale yellow, cloudy solution formed. (TLC (1:2 ethyl acetate/hexanes)) indicated disappearance of the starting material. The reaction was quenched by adding 10% aqueous NaOH (200 mL). After stirring for 45 minutes, 10% citric acid solution (300 mL) was added until, pH ˜5.0. The product was extracted with ethyl acetate (500 mL). The organic phase was washed with brine and dried over MgSO4, and filtered. The filtrate was concentrated under reduced pressure to provide an off white solid (yield: 4.1 g, 84%).

1. stirringwhile stirring
2. temperatureto warm to room temperature
3. stirringStirring
4. waitcontinued for an additional 2 hours
5. customA pale yellow, cloudy solution formed
6. customThe reaction was quenched
7. additionby adding 10% aqueous NaOH (200 mL)
8. stirringAfter stirring for 45 minutes
9. addition10% citric acid solution (300 mL) was added until, pH ˜5.0
10. extractionThe product was extracted with ethyl acetate (500 mL)
11. washThe organic phase was washed with brine
12. dry with materialdried over MgSO4
13. filtrationfiltered
14. concentrationThe filtrate was concentrated under reduced pressure

ORD-Eintrag

ord-c2237f2bc76c4eabbb4c0f5d3d4bdc30

Quelldatensatz

uspto-grants-2001_10

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06307047B1