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

Participants

Reaction Conditions

Reaction Steps

21.8 g (67.5 mmol) of 9-(4-bromophenyl)-9H-carbazole was put into a 500 mL three-neck flask. The air in the flask was replaced with nitrogen. To the mixture were added 200 mL of tetrahydrofuran (THF), and then the solution was cooled to −78° C. Into this solution, 48.9 mL (74.3 mmol) of n-butyllithium (a 1.52 mol/L hexane solution) was dropped, and the solution was stirred at the same temperature for 2 hours. After the stirring, 17.4 mL (155 mmol) of trimethyl borate was added to the solution, and the solution was stirred for about 1 hour at the same temperature. Then, the mixture was stirred for 24 hours while the temperature of the solution was being increased to room temperature. Thereafter, to the solution was added about 200 mL (1.0 mol/L) of hydrochloric acid, and then the solution was stirred at room temperature for 1 hour. The organic layer of the mixture was washed with water, and then the aqueous layer was extracted with acetate ether. The extract was combined with the organic layer and then washed with a saturated saline solution. The organic layer was dried with magnesium sulfate. After the drying, the mixture was subjected to suction filtration, and then the obtained filtrate was condensed. The obtained residue was recrystallized with chloroform/hexane to give 12.8 g of a white powdered solid, which was the object of the synthesis, at a yield of 65.9%. A synthesis scheme of Step 2 is shown in (f-2) given below.

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