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

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Reaction Steps

To benzofuran-5-carbonitrile (500 mg, 3.49 mmol) in THF (9.98 mL) at −78° C. was added n-BuLi 1.6M in hexanes (2.401 mL, 3.84 mmol) dropwise. The mixture was stirred for 30 min at this temperature, and then trimethyl borate (0.858 mL, 7.68 mmol) was added dropwise. The mixture was stirred for 20 min, and then HCl (2M, 11.52 mL, 23.05 mmol) was added. The bath was removed, and then stirred for 30 min. To the mixture was added more water and extracted with EtOAc three times, dried over magnesium sulfate, filtered, concentrated. crude 7a (623 mg, 87%) was then dried and used as is for next step.

Provenance & Evidence