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

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence