Hydrochloric Acid → (5-Fluoro-1-benzofuran-2-yl)boronic acid

Participants

Reaction Conditions

Reaction Steps

In a nitrogen atmosphere, to a solution of 2.0 g of 5-fluorobenzofuran in 150 ml tetrahydrofuran was added 18.5 ml of a 1.59 M solution of n-butyllithium in n-hexane at −78° C., and the mixture was stirred at the same temperature for 10 minutes and at 0° C. for further 10 minutes. At −78° C., 3.7 ml of triethoxyborane was added, and the mixture was stirred for 2 hours while elevating to 0° C. 30 ml of 1 N hydrochloric acid was added, stirred at room temperature for 1 hour, and then the mixture was extracted with ethyl acetate. The extract was washed with brine, dried over anhydrous magnesium sulfate and the solvent was evaporated. The crude product was purified and separated by silica gel column chromatography (ethyl acetate:n-hexane=1:3 to 1:1), to give 525 mg of the title compound as colorless crystals.

Provenance & Evidence