Triisopropyl borate → 5-Ethoxymethoxy-benzofuran-2-boronic acid

Participants

Reaction Steps

To a stirred solution of 5-ethoxymethoxy-benzofuran (3) (265 mg, 1.38 mmol) in THF (5 mL) at −78° C., n-butyllithium (2.5M solution in hexane, 0.56 mL, 1.44 mmol) was added drop wise. After the reaction mixture was stirred for 1 hour, triisopropylborate (0.635 mL, 2.76 mmol) was added slowly and the stirring was continued for additional 20 minutes at −78° C. The reaction mixture was quenched with saturated ammonium chloride solution (10 mL) and was allowed to warm to room temperature. Water (10 mL) was added and the resulting mixture was extracted in diethyl ether (2×50 mL). The combined extracts were washed with brine, dried over MgSO4, and concentrated under reduced pressure. Purification of the crude product by recrystallization from ethyl acetate and hexane afforded the desired compound (4) (170 mg) as a white solid.

Provenance & Evidence