Sulfuric Acid → 3-Cyanophenylboronic acid

Participants

Reaction Conditions

Reaction Steps

In 100 ml of anhydrous tetrahydrofuran, was dissolved 20 g of 3-bromobenzonitrile. To the resulting solution, was added 37.6 ml of triisopropoxyborane under a nitrogen atmosphere. The formed solution was cooled to −78° C., and 98.3 ml of a 1.6 M solution of n-butyllithium in hexane was dropped thereinto under stirring for about 30 minutes. After stirring the resulting mixture at room temperature for 30 minutes, the mixture was then cooled to 0° C., and 220 ml of a 4 M sulfuric acid was added. The prepared solution was refluxed overnight and subsequently recooled to 0C. To the cooled solution, was added 340 ml of a 5 M aqueous solution of sodium hydroxide. The resulting solution was extracted with 200 ml of diethyl ether, and an aqueous layer was separated. To the aqueous layer, was added a 6 M hydrochloric acid until pH attained 2. The resulting mixture was extracted with 300 ml of ethyl acetate twice. The extract was dried over magnesium sulfate, and the solvent was then evaporated. The resulting crude product was recrystallized from dimethylformamide-water to provide 11.6 g (72%) of the title compound as a needlelike light-yellow crystal.

Provenance & Evidence