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

Participants

Reaction Steps

The polar diastereoisomer of 3-(1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide (214 mg, 0.467 mmole) was dissolved in abs. ethanol (3 ml). Citric acid (90.6 mg, 0.471 mmole) was added in one portion at ca. 40° C. while stirring. The reaction mixture was stirred for 2 hours at RT. During this time no precipitate formed. Ethanol was distilled off down to a volume of 1 ml. Diethyl ether (10 ml) was added to the residue. The suspension was stirred for 20 hours at RT. The precipitate was filtered off, washed with diethyl ether (3×1.5 ml) and dried in vacuo. The polar diastereoisomer of 3-(1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide citrate (297 mg, m.p. 116°-120° C., 98%, Example 48) was a cream-coloured solid.

Provenance & Evidence