3.6 g of diphenyl ether and 70 mg of 10% palladium-carbon were added to 180 mg of N-(2-dimethylaminoethyl)-5,6,7,8-tetrahydrocarbazole-3,4dicarboximide. The mixture was refluxed in a nitrogen stream for 15 minutes, and then cooled to room temperature. Thereto was added 40 ml of chloroform. The resulting insoluble material was removed by filtration. The filtrate was mixed with 25 ml of water. The mixture was adjusted to pH 1.0 with 6N hydrochloric acid. The aqueous layer was separated, washed with 10 ml of chloroform, and mixed with 20 ml of chloroform. The mixture was adjusted to pH 7.5 with an aqueous saturated sodium hydrogencarbonate solution. The organic layer was separated, washed with an aqueous saturated sodium chloride solution, and dried over anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure. The residue was recrystallized from ethanol to obtain 100 mg (yield: 56%) of N-(2-dimethylaminoethyl)-carbazole-3,4-dicarboximide as yellow needles.
