Hydrochloric Acid → 3,5-Difluorophenyl boric acid

Participants

Reaction Steps

To a mixture of 1-bromo-3,5-difluorobenzene (743 mmol) and 500 ml of THF was added dropwise 500 ml of a solution of n-butyl lithium (corresponding to 780 mmol) in hexane at −78° C. in 1.6 hours, and stirred at the same temperature for 1.5 hours. To this solution was wadded dropwise 200 ml of a solution of triisopropyl borate (1,486 mmol) in THF, the solution was gradually warmed up to room temperature, and then the solution was stirred overnight. After 750 ml of 7.3% hydrochloric acid was added and stirred for 30 min, the reaction solution was extracted twice with diethyl ether, washed thrice with water, and then dried over anhydrous magnesium sulfate. The solvent was distilled off and the residue was recrystallized from about 1,000 ml of toluene to give a white solid of 3,5-difluorophenyl boric acid (520 mmol).

Provenance & Evidence