5-fluoro-3-(piperidin-3-yl)-1H-indole → 3-(5-fluoro-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide

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Reaction Steps

The diastereoisomer mixture of (4-dimethylamino-4-phenylcyclohexylmethyl)-carbamic acid 4-nitrophenyl ester (400 mg, 1 mmole) was added to a solution of 5-fluoro-3-piperidine-3-yl-1H-indole (220 mg, 1 mmole) in dioxane (8 ml). The reaction mixture was then boiled under reflux for 8 hours. The reaction mixture was worked up by distilling off the solvent. The residue contained, apart from nitrophenol, also the two diastereoisomers of 3-(5-fluoro-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide. The diastereoisomers were separated and purified by flash chromatography on silica gel (30 g). Methanol/EE (1:1; 850 ml) was used as eluent. The non-polar diastereoisomer of 3-(5-fluoro-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide (143 mg, m.p. 110°-115° C., 30%) and the polar diastereoisomer of 3-(5-fluoro-1H-indol-3-yl)piperidine-1-carboxylic acid-(4-dimethylamino-4-phenylcyclohexylmethyl)-amide (118 mg, m.p. 98°-101° C., 25%) were thereby obtained in pure form.

Provenance & Evidence