Tetrahydrofuran → 4-Ethoxy-3-(trifluoromethyl)benzeneboronic acid

Temperature

-78 °C

A solution of 4-bromo-1-ethoxy-3-trifluoromethyl-benzene (21.25 g, 90.8 mmol) in dry tetrahydrofuran (120 ml) was purged with nitrogen, cooled to −78° C. and BuLi (2.5 M solution in hexanes, 39.96 ml, 99.9 mmol) added dropwise maintaining a temperature below −70° C. The mixture was stirred for 5 minutes before addition of triisopropyl borate (17.9 g, 95.36 mmol) in one portion. Stirring was continued at −78° C. for 30 minutes before allowing to come to room temperature. The reaction was quenched by addition of 10 ml of acetic acid dissolved in 150 ml water before concentration under reduced pressure to remove tetrahydrofuran. The precipitate was collected by filtration, dissolved in ethyl acetate and dried over sodium sulfate. Purification was achieved by recrystalisation from ethyl acetate/hexane mixtures to afford 4-ethoxy-3-trifluoromethylphenylboronic acid (10 g). 1H NMR (DMSOd6): δ 8.08 (s, 1H) 8.01 (d, 1H) 7.2 (d, 1H) 4.18 (q, 2H) 1.34 (t, 3H).

1. temperaturemaintaining a temperature below −70° C
2. customto come to room temperature
3. customThe reaction was quenched by addition of 10 ml of acetic acid
4. dissolutiondissolved in 150 ml water before concentration under reduced pressure
5. customto remove tetrahydrofuran
6. filtrationThe precipitate was collected by filtration
7. dissolutiondissolved in ethyl acetate
8. dry with materialdried over sodium sulfate
9. customPurification
10. customwas achieved by recrystalisation from ethyl acetate/hexane

ORD record

ord-a29f4051106a44ffa3678c6695231e82

Source dataset

uspto-grants-2010_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07687515B2