Hexane → [5-(Trifluoromethyl)pyridin-3-yl]boronic acid

Temperature

-78 °C

To a solution of 3-bromo-5-(trifluoromethyl)pyridine (2.5 g, 11.06 mmol) and triisopropylborate (3.06 mL, 13.27 mmol) in anhydrous tetrahydrofuran (20 mL) at −78° C. under nitrogen was added dropwise a solution of n-butyl lithium in hexane (2.5 M, 4.9 mL, 12.17 mmol) The reaction was stirred at −78° C. for 3 hours then allowed to warm slowly to −10° C. The reaction mixture was then quenched by the addition of water (20 mL) and the tetrahydrofuran removed under reduced pressure. The resulting aqueous phase was diluted with water (40 mL) and washed with ether (2×40 mL). The aqueous phase was then acidified to pH 5 by the addition of acetic acid and the resulting suspension extracted with ethyl acetate (80 mL). The organic phase was separated, dried (MgSO4), filtered and concentrated under reduced pressure to give 3-(trifluoromethyl)pyridine-5-boronic acid (2.022 g, 96% yield) as a tan solid.

1. temperatureto warm slowly to −10° C
2. customThe reaction mixture was then quenched by the addition of water (20 mL)
3. customthe tetrahydrofuran removed under reduced pressure
4. additionThe resulting aqueous phase was diluted with water (40 mL)
5. washwashed with ether (2×40 mL)
6. additionThe aqueous phase was then acidified to pH 5 by the addition of acetic acid
7. extractionthe resulting suspension extracted with ethyl acetate (80 mL)
8. customThe organic phase was separated
9. dry with materialdried (MgSO4)
10. filtrationfiltered
11. concentrationconcentrated under reduced pressure

ORD record

ord-da827d2819b6448c8318b48664dee89c

Source dataset

uspto-grants-2016_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09409893B2