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

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Reaction Steps

Then, 21.8 g (67.5 mmol) of 9-(4-bromophenyl)carbazole was put into a 500 mL three-necked flask, and the air in the flask was replaced with nitrogen. Then, 200 mL of tetrahydrofuran (THF) was added thereto. The temperature in the flask was set to be −78° C. and then, 48.9 mL (74.3 mmol) of n-butyllithium (1.52 mol/L, hexane solution) was dropped to the mixture and was stirred for 2 hours at the same temperature. Then, 17.4 mL (155 mmol) of trimethyl borate was added thereto. The mixture was stirred for one hour at the same temperature, then, was stirred for 24 hours while raising the temperature to room temperature. After the reaction, 200 mL of hydrochloric acid (1.0 mol/L) was added to the reaction mixture, and then stirred for one hour at room temperature. After that, the organic layer in the reaction mixture was washed with water and the product was extracted with ethyl acetate from the water which was used for the washing. The obtained extraction solution and the organic layer, which was washed with water, were mixed. The mixture was further washed with a saturated aqueous solution of sodium chloride, and then dried with magnesium sulfate. After the drying, the mixture was suction filtrated, and the filtrate was concentrated. The obtained residue was recrystallized with a mixed solvent of chloroform and hexane to give 12.8 g of a white powdered solid of 4-(carbazol-9-yl)phenylboronic acid (yield: 65.9%). A synthesis scheme (f-3) of 4-(carbazol-9-yl)phenylboronic acid is shown below.

Provenance & Evidence