Hydrochloric Acid → 3-Chloro-2-fluorophenylboronic Acid

Participants

Reaction Conditions

Reaction Steps

In a 500-mL three-neck flask was put 16 g (72 mmol) of 1-bromo-3-chloro-2-fluorobenzene, and the air in the flask was replaced with nitrogen; then, 200 mL of tetrahydrofuran was added and the solution was cooled down to −80° C. under a nitrogen stream. To this solution, 48 mL (76 mmol) of n-butyl lithium (a 1.6 mol/L hexane solution) was added dropwise with a syringe, and then the mixture was stirred for 1.5 hours at the same temperature. After stirring, 9.0 mL (80 mmol) of trimethyl borate was added to this mixture. While the temperature was raised to room temperature, the mixture was stirred for about 19 hours. After stirring, about 100 mL of a 1 mol/L hydrochloric acid was added to the resulting solution and the mixture was stirred. The organic layer of this mixture was washed with water and the aqueous layer was subjected to extraction with toluene twice. The solution of the extract and the organic layer were combined and washed with a saturated aqueous solution of sodium chloride. The resulting organic layer was dried over magnesium sulfate, and this mixture was gravity-filtered. The resulting filtrate was concentrated to give 4.5 g of a pale yellow solid of a target substance, in a yield of 35%.

Provenance & Evidence