Citric Acid → 1-(6-Chloro-2,3,4,9-tetrahydro-1H-beta-carbolin-1-yl)cyclobutanecarboxamide Hydrochloride

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Reaction Conditions

Reaction Steps

0.8 g of tert-butyl pyrocarbonate is added at 0° C. to a solution of 1 g of the compound of Example 1 in 20 ml of dioxane, 20 ml of water and 10 ml of 1M sodium hydroxide solution. After reaction for 4 hours, the reaction mixture is diluted by the addition of water and acidified with a 5% citric acid solution. After extraction with ethyl acetate, drying the organic phases, and concentration under reduced pressure, the residue obtained is diluted with 50 ml of tetrahydrofuran and 0.5 ml of N-methylmorpholine. After cooling the mixture to −10° C., 0.3 ml of ethyl chloroformate are added, followed by 0.2 ml of a 28% ammonium hydroxide solution. After reaction for 12 hours, the solvent is distilled off. The residue is then taken up in a water/dichloromethane mixture. After decanting, drying and concentrating under reduced pressure, the residue is treated with a solution of ethanol and ethereal hydrogen chloride, enabling the desired product to be obtained in the form of the hydrochloride.

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