Hydrochloric Acid → 4-(9H-Carbazol-9-yl)phenylboronic Acid

Participants

Reaction Steps

In a 500 mL three-neck flask was put 21.8 g (67.5 mmol) of 9-(4-bromophenyl)-9H-carbazole. The atmosphere in the flask was replaced with nitrogen. To the mixture was added 200 mL of tetrahydrofuran (THF). The temperature of this solution was set to −78° C., and then 48.9 mL (74.3 mmol) of n-butyllithium (a 1.52 mol/L hexane solution) was dripped to the solution. The mixture was stirred at the same temperature for 2 hours. After that, 17.4 mL (155 mmol) of trimethyl borate was added to the mixture, followed by stirring for 1 hour at the same temperature. Then, the mixture was stirred for 24 hours while the temperature thereof is returned to room temperature. After that, 200 mL of 1.0 mol/L hydrochloric acid was added to this solution, followed by stirring for 1 hour at room temperature. The organic layer of the mixture was washed with water, and the aqueous layer was extracted with ethyl acetate. The extract and the organic layer were combined, washed with saturated brine, and then dried with magnesium sulfate. After that, this mixture was suction filtered. The resulting filtrate was concentrated to give a residue. This residue was recrystallized with a mixed solvent of chloroform and hexane to give 4-(9H-carbazol-9-yl)phenylboronic acid which was the desired substance as 13 g of a white powdered solid in a yield of 66%.

Provenance & Evidence