Hydrochloric Acid → 9-Ethyl-6,7,8,9-tetrahydro-5H-carbazole-3-carboxylic acid

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Reaction Steps

Then, 480 mg of the N-ethyl-1,2,3,4-tetrahydrocarbazole-6-carboxylic acid methyl ester was dissolved in 5 mL of methanol, added with 4 mL of 4 N aqueous sodium hydroxide, and stirred at room temperature for 2 hours. Subsequently, the reaction mixture was cooled and then neutralized with hydrochloric acid, and the deposited precipitates were collected to obtain 400 mg of N-ethyl-1,2,3,4-tetrahydrocarbazole-6-carboxylic acid. The obtained N-ethyl-1,2,3,4-tetrahydrocarbazole-6-carboxylic acid (73 mg), 6-(1-naphthalenesulfonyl)-aminopentylamine (100 mg) obtained in Example 36 and WSC (68 mg) were dissolved in 2 mL of DMF and the mixture was stirred at room temperature for 4 hours. The reaction mixture was added with water and extracted with ethyl acetate. Then, the organic layer was washed with water and dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The residue was purified by silica gel chromatography (eluent: chloroform/ethyl acetate=95/5) to obtain 50 mg of Compound 1-45.

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