Triisopropyl borate → 3,5-Dimethylisoxazole-4-boronic acid

Temperature

-78 °C

To a 500 mL three RB flask fitted with magnetic stirrer was charged 4-bromo-3,5-dimethyl-1,2-oxazole (4.0 g, 22.7 mmol) in THF (40 mL), cooled −78° C. To the stirred solvent was added n-butyl lithium (28.4 mL, 1.6M solution, 45.0 mmol) drop wise and stirred at −65° C. about 30 minutes. The RM was brought to −78° C., was added tri-isopropyl borate (12.81 g, 68.0 mmol), once the temperature to reached room temperature and stirred about 16 h. Then removed the solvent under reduced pressure and quenched with saturated NH4Cl solution and extracted with ethyl acetate. The organic layer was washed with water, dried over anhydrous Na2SO4 and removed the solvent under reduced pressure. The obtained crude material was purified by silica gel column chromatography to obtain white solid. (0.4 g, yield: 12.5%).

1. customwas brought to −78° C.
2. customto reached room temperature
3. stirringstirred about 16 h
4. customThen removed the solvent under reduced pressure
5. customquenched with saturated NH4Cl solution
6. extractionextracted with ethyl acetate
7. washThe organic layer was washed with water
8. dry with materialdried over anhydrous Na2SO4
9. customremoved the solvent under reduced pressure
10. customThe obtained crude material
11. customwas purified by silica gel column chromatography
12. customto obtain white solid

ORD record

ord-efdcd2fa9b954c05b0076458ad826a1c

Source dataset

uspto-grants-2016_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09278915B2