Hydrochloric Acid → (3,4-Dihydroxyphenyl)boronic acid

Participants

Reaction Steps

4-Bromocatechol (T-1) (18.8 g; made by Tokyo Chemical Industry Co., Ltd.) was dissolved in dry THF (200 ml), which was cooled to −70° C. n-BuLi (72 ml) was added under an atmosphere of nitrogen and the stirring was continued at −70° C. for 2 hours. Trimethyl borate (15.6 g) in a THF solution was then slowly added dropwise at −70° C., and the mixture was warmed to room temperature and stirred for 16 hours. After the completion of the reaction, 2N HCl (100 ml) was added and the mixture was extracted with toluene. The extract was washed with water and brine, and dried over anhydrous magnesium sulfate. The extract was concentrated under reduced pressure to give pale brown solids. The solids were recrystallized (heptane:toluene=4:1 by volume) to give 3,4-dihydroxyphenylboronic acid (T-2; 9.7 g; yield 63%) as colorless crystals.

Provenance & Evidence