Hydrochloric Acid → 9-Phenyl-9H-carbazole-3-boronic acid

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Reaction Steps

In a 500 mL three-neck flask were stirred 29 g (90 mmol) of 3-bromo-9-phenylcarbazole obtained by the above Step 3 described in Synthesis Example 1 and 200 mL of tetrahydrofuran (abbreviation: THF) at −78° C. to provide a solution. Then, 110 mL (69 mmol) of n-butyllithium (1.6 mol/L hexane solution) was dropped therein, and the mixture was stirred for 2 hours at the same temperature. Furthermore, 13 mL (140 mmol) of trimethyl borate was added therein, and the mixture was stirred for 24 hours at room temperature. After the reaction, 200 mL of 1.0 mol/L hydrochloric acid was added therein, and the mixture was stirred for 1 hour at room temperature. This mixture was washed with water, aqueous sodium hydroxide, and water in this order, and magnesium sulfate was added so that the moisture was removed. This suspending solution was filtered and the obtained filtrate was concentrated. Then, chloroform and hexane were added therein, ultrasonic waves were applied thereto, and then recrystallization thereof was performed. Accordingly, 21 g of a powdery white solid of 9-phenyl-9H-carbazol-3-boronic acid, which was the object of the synthesis, was obtained in a yield of 80% (synthesis scheme (b-1)).

Provenance & Evidence