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

Participants

Reaction Conditions

Reaction Steps

10 g (32 mmol) of 3-bromo-9-phenyl-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 150 mL of tetrahydrofuran (THF), and then the solution was cooled to −80° C. Into this solution, 22 mL (36 mmol) of n-butyllithium (a 1.61 mol/L hexane solution) was dropped by a syringe. After the dropping was completed, this solution was stirred at the same temperature for 1 hour. After the stirring, 4.6 mL, (40 mmol) of trimethyl borate was added to the solution, and the solution was stirred for about 15 hours while the temperature of the solution was being increased to room temperature. Thereafter, to the solution was added about 50 mL (1.0 mol/L) of dilute hydrochloric acid, and then the solution was stirred for 1 hour. After the stirring, the aqueous layer of the mixture was extracted with ether acetate. The extract was combined with the organic layer and then washed with a saturated sodium hydrogen carbonate solution. The organic layer was dried with magnesium sulfate. After the drying, this mixture was subjected to gravity filtration. The obtained filtrate was condensed to give an oily light brown substance. The obtained oily substance was recrystallized with chloroform/hexane to give 6.2 g of a light brown powder, which was the object of the synthesis, at a yield of 68%. A synthesis scheme of Step 1 is shown in (d-1) given below.

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