Trimethyl borate → 4-Ethoxy-3-fluoro-2-formylphenylboronic acid

Participants

Reaction Conditions

Reaction Steps

Under a nitrogen atmosphere, n-BuLi (43.3 mL, 71.42 mmol) was slowly added dropwise, at −70° C. or lower, to a THF (200 mL) solution of compound (54) (19.8 g, 68.02 mmol). The reaction mixture was agitated at −70° C. or lower for 1 hour, and then trimethyl borate (10.6 g, 102.0 mmol) was slowly added dropwise thereto. The reaction mixture was returned to room temperature, and then quenched with 200 mL of 2N hydrochloric acid aqueous solution, and extracted with 100 mL of toluene three times. Combined organic layers were washed with a saturated aqueous solution of sodium hydrogencarbonate, water and saturated brine, and then dried over magnesium sulfate, and a solvent was distilled off by an evaporator. The residue was washed with heptane, and thus (4-ethoxy-3-fluoro-2-formylphenyl)boronic acid (55) (9.85 g, yield 68.3%) was obtained.

Provenance & Evidence