Hexane → (1-Benzofuran-5-yl)boronic acid

A solution of n-butyl lithium in hexane (1.5M; 3.72 ml, 5.6 mmol) was added dropwise to a solution of 5-bromobenzo[b]furan (1.0 g, 5.0 mmol) in tetrahydrofuran (10 ml) under argon atmosphere at −60° C. and the mixture was stirred at the same temperature for 30 min. To the mixture was added trimethyl borate (0.69 ml, 6.0 mmol) and temperature of the mixture was raised to room temperature in 4 hrs. Water (5 ml) was added to the reaction mixture at 5° C. and tetrahydrofuran was distilled off under reduced pressure. To the residue was added 1N hydrochloric acid (pH 1) and the mixture was extracted with ethyl acetate. The organic layer was washed with brine and dried. The solvent was distilled off and the residue was triturated with a mixture of n-hexane/diethyl ether, filtered and dried to give 5-benzo[b]furan boronic acid (551 mg) as a pale brown solid.

1. distillationtetrahydrofuran was distilled off under reduced pressure
2. additionTo the residue was added 1N hydrochloric acid (pH 1)
3. extractionthe mixture was extracted with ethyl acetate
4. washThe organic layer was washed with brine
5. customdried
6. distillationThe solvent was distilled off
7. customthe residue was triturated with a mixture of n-hexane/diethyl ether
8. filtrationfiltered
9. customdried

ORD record

ord-d3ede265d8044d7eba5844980b6936c0

Source dataset

uspto-grants-2008_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07345068B2