Hydrochloric Acid → 2-(Trifluoromethoxy)phenylboronic Acid (contains varying amounts of Anhydride)

Participants

Reaction Conditions

Reaction Steps

A solution of 2-bromo-trifluoromethoxybenzene (1.0 g, 4.15 mmol) in dry tetrahydrofuran (20 mL) was cooled to −70° C. A 2.5 M solution of n-butyllithium in hexanes (2.0 mL, 4.98 mmol) was slowly added over a 5 min period, keeping the temperature below −65° C. After stirring at −70° C. for 30 min, triisopropylborate (1.5 mL, 6.22 mmol) was added over a 5 min period. After stirring at −70° C. for 30 min, the solution was stirred at room temperature overnight. An aqueous solution of 2N HCl (10 mL) was added and the mixture stirred for 2 hr. The solution was diluted with ethyl acetate (100 mL). The layers were separated and the organic layer successively washed with 2N HCl (2×25 mL), water (1×25 mL), and saturated salt solution (1×25 mL). The solution was dried over anhydrous magnesium sulfate, filtered and concentrated by rotoevaporation to a pale crystalline solid which was triturated with a little hexanes and filtered. The filtrate was concentrated to a white solid. The two solids were combined to yield 434 mg of the title compound which was used without further purification in the subsequent reaction.

Provenance & Evidence