Trimethyl borate → (4,5-Difluorobenzofuran-7-yl)boronic acid

Temperature

-5 °C

A mixture of 2.0 gm (8.58mMol) 4,5-difluoro-7-bromobenzofuran and 0.202 gm (8.58 mMol) magnesium in 10 mL tetrahydrofuran was heated at reflux for 50 minutes. The resulting mixture was then cooled to −5° C. and treated dropwise with 1.01 mL (8.93 mMol) trimethylborate over 20 minutes. The reaction mixture was stirred at room temperature for 1.5 hours and was then concentrated under reduced pressure. The residue was partitioned between 50 mL deionized water and 50 mL ethyl acetate. The mixture was treated with 0.3 mL acetic acid to adjust to a neutral pH. The phases were separated and the aqueous phase was extracted well with ethyl acetate. The organic phases were combined, dried over magnesium sulfate, and concentrated under reduced pressure to provide 2.1 gm of the title compound.

1. temperaturewas heated
2. temperatureat reflux for 50 minutes
3. concentrationwas then concentrated under reduced pressure
4. customThe residue was partitioned between 50 mL
5. additionThe mixture was treated with 0.3 mL acetic acid
6. customThe phases were separated
7. extractionthe aqueous phase was extracted well with ethyl acetate
8. dry with materialdried over magnesium sulfate
9. concentrationconcentrated under reduced pressure

ORD record

ord-58a866e078714fc9b144d3a8df6cd6e9

Source dataset

uspto-grants-2005_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06881733B1