4-[3-(1H-indol-3-yl)propylidene]-1-butyl-N,N-dimethylcyclohexanamine → N,N-dimethyl-N-(4-butyl-2',3',4',9'-tetrahydro-1H-spiro[cyclohexane-1,1'-carbazole]-4-yl)amine

Participants

Reaction Conditions

Reaction Steps

p-toluol sulphonic acid (323 mg, 1.7 mmol) was added to a solution 4-[3-(1H-indol-3-yl)propylidene]-1-butyl-N,N-dimethylcyclohexanamine (289 mg, 0.85 mmol) in absolute toluol (10 mL) and stirred for 18 h at 100° C. The reaction solution was then diluted with dichloromethane (30 mL) and washed with 1 N sodium carbonate solution (2×30 mL), water and saturated sodium chloride solution (30 mL each) one after the other, dried with sodium sulphate and concentrated to low volume in a vacuum. The raw product (272 mg) was mixed with methanol (100 mL) and stirred overnight at room temperature, during which very little precipitate was formed (light-coloured solid). The 1H-NMR spectrum and the LC-MS data showed that this concerned two isomers, and the 1H-NMR spectrum revealed that these were present in a ratio of approx. 1:1 and olefin side-products were present at most in very small quantity. The reaction solution was concentrated to low volume in a vacuum (259 mg, 90%). The diastereomer mixture was separated by preparative HPLC.

Provenance & Evidence