Hydrochloric Acid → 4-(Trifluoromethyl)phenylboronic acid

An oven dried Schlenk tube was charged with magnesium turnings (766 mg, 31.5 mmol), evacuated, and backfilled with argon. To the reaction vessel was added 10 mL of ether followed by 4-(trifluoromethyl)phenyl bromide (4.20 mL, 30.0 mmol). The reaction mixture was stirred without external heating for 1 hour, during which time an exotherm occurred and then subsided. The solution was diluted with ether (10 mL) and transferred via cannula to a flask containing triisopropylborate (13.8 mL, 60.0 mmol) in 1:1 THF/ether (20 mL) at −78° C. The resulting reaction mixture was kept at −78° C. for 15 minutes and then was allowed to warm to room temperature. After stirring at room temperature for 15 minutes, the reaction mixture was poured onto 2.0 M HCl (60 mL). The mixture was transferred to a separatory funnel, extracted with ethyl acetate (60 mL), washed with water (60 mL), and brine (60 mL). The organic solution was dried over anhydrous sodium sulfate and concentrated in vacuo. The crude material was dissolved in 2:1 hexane/ethyl acetate (90 ml,) and activated charcoal was added. The mixture was filtered and the product crystallized upon cooling. The crystals were collected by filtration to afford 1.98 g (35%) of pale yellow needles.

1. customAn oven dried Schlenk tube
2. customevacuated
3. additionTo the reaction vessel was added 10 mL of ether
4. temperaturewithout external heating for 1 hour, during which time an exotherm
5. customtransferred via cannula to a flask
6. customThe resulting reaction mixture
7. stirringAfter stirring at room temperature for 15 minutes
8. customThe mixture was transferred to a separatory funnel
9. extractionextracted with ethyl acetate (60 mL)
10. washwashed with water (60 mL), and brine (60 mL)
11. dry with materialThe organic solution was dried over anhydrous sodium sulfate
12. concentrationconcentrated in vacuo
13. dissolutionThe crude material was dissolved in 2:1 hexane/ethyl acetate (90 ml,) and activated charcoal
14. additionwas added
15. filtrationThe mixture was filtered
16. customthe product crystallized
17. temperatureupon cooling
18. filtrationThe crystals were collected by filtration

ORD record

ord-f388e93d7d6f448d9c7144ffd4df968c

Source dataset

uspto-grants-2001_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06307087B1