3-(2-(4-Pyridyl)ethyl)indole → 1-butyl-N,N-dimethyl-4,4-bis(3-(2-(pyridin-4-yl)ethyl)-1H-indol-2-yl)cyclohexanamine

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Reaction Steps

3-(2-pyridin-4-ylethyl)-1H-indole (667 mg, 3 mmol, synthesis cf. WO2008009415, indole unit Ind-14) together with 4-butyl-4-(dimethylamino)cyclohexanone (592 mg, 3 mmol, synthesis cf. WO2008009415, ketone unit Ket-4) was dissolved in dichloromethane (45 ml) and mixed with trifluoromethane sulphonic acid (0.553 ml, 6.3 mmol). The batch was stirred for 67 h at RT, and a brown oil separated out. For work up the reaction solution was mixed with 1N NaOH (10 ml) and THF (10 ml). The mixture was stirred a further 60 min. After separation of the phases the aqueous phase was extracted with dichloromethane (3×10 ml). The combined organic extracts were dried over Na2SO4 and then concentrated to low volume. The raw product obtained (1.24 g) was purified by column chromatography [silica gel 60 (100 g); ethyl acetate/methanol (10:1, 1200 ml), ethyl acetate/methanol (5:1, 600 ml) ethyl acetate/methanol (2:1, 700 ml), ethyl acetate/methanol (1:2, 750 ml), methanol (800 ml)].

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