Citric Acid → 4-(5-chloro-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide citrate

Participants

Reaction Steps

The polar diastereoisomer of 4-(5-chloro-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide (267 mg, 0.54 mmole) was dissolved in abs. ethanol (7 ml). Citric acid (105.1 mg, 0.55 mmole) was added in one portion at ca. 35° C. while stirring. After stirring for several hours at RT no precipitate was visible. The reaction mixture was reduced to ca. 1 ml of solution and diethyl ether (25 ml) was added in portions. The precipitate formed was filtered off after 18 hours, washed with Et2O (3×2 ml) and dried in vacuo. The polar citrate of 4-(5-chloro-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide (324 mg, m.p. 125°-130° C., 88%, Example 19) was a colourless solid.

Provenance & Evidence