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

Participants

Reaction Conditions

Reaction Steps

Into a 500 mL three-neck flask were put 10 g (31 mmol) of 3-bromo-9-phenyl-9H-carbazole. The air in the flask was replaced with nitrogen. 150 mL of tetrahydrofuran (THF) were put into the flask, and 3-bromo-9-phenyl-9H-carbazole was dissolved therein. This solution was cooled to −80° C. Into this solution were dripped 20 mL (32 mmol) of n-butyllithium (a 1.58 mol/L hexane solution) with the use of a syringe. After the dripping was completed, this solution was stirred at the same temperature for 1 hour. After the stirring, 3.8 mL (34 mmol) of trimethyl borate were added to the solution, and the solution was stirred for about 15 hours while the temperature of the solution was being brought back to room temperature. Thereafter, about 150 mL (1.0 mol/L) of dilute hydrochloric acid were added to the solution, and then the solution was stirred for 1 hour. After the stirring, an aqueous layer of the mixture was extracted with ethyl acetate. The extract was combined with an organic layer and then washed with a saturated sodium hydrogen carbonate solution. The organic layer was dried with magnesium sulfate. After the drying, the mixture was subjected to gravity filtration. The obtained filtrate was condensed to give an oily light brown substance. The obtained oily substance was dried under reduced pressure to give 7.5 g of a light brown solid, which was the object of the synthesis, at a yield of 86%. A synthesis scheme of Step 1 is shown in (b-1) given below.

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