Hydrochloric Acid → 4-(Di-n-propyl)amino-1,2,2a,3,4,5-hexahydrobenz[cd]indole

Participants

Reaction Steps

Four and six-tenths grams of 1-benzoyl-4-keto-1,2,2a,3,4,5-hexahydrobenz[d]indole and 12.4 g. of ammonium acetate were suspended in 400 ml. of methanol. 1.07 g. of sodium cyanoborohydride were added and the resulting mixture stirred at ambient temperature for 17 hours. The reaction mixture was then poured over a mixture of ice and 1N aqueous hydrochloric acid. This mixture was washed with ether and the resulting organic layer discarded. The aqueous layer was then made basic with 14N ammonium hydroxide and the alkaline layer extracted several times with a mixture of chloroform and isopropanol. The organic extracts were combined and the combined extracts washed with saturated aqueous sodium chloride and then dried. Evaporation of the solvent yielded 3.9 g. of a foam consisting of 1-benzoyl-4-amino-1,2,2a,3,4,5-hexahydrobenz[cd]indole. The compound was dissolved in 150 ml. of methanol and 700 mg. of sodium cyanoborohydride were added followed by 6.6 ml. of propionaldehyde. The resulting reaction mixture was stirred at ambient temperature for 22 hours and then worked up by the same procedure as for the primary amine. A residue was obtained consisting of 5.1 g. of an oil comprising 1-benzoyl-4-(di-n-propyl)amino-1,2,2a,3,4,5-hexahydrobenz[cd]indole. This compound was in turn dissolved in 120 ml. of 6N aqueous hydrochloric acid and the acidic solution refluxed under a nitrogen atmosphere for 45 minutes. The reaction mixture was poured onto ice and the acidic aqueous layer made basic with 14N ammonium hydroxide. The alkaline layer was extracted several times with a chloroform-isopropanol solvent mixture. The organic extracts were combined, the combined extracts washed with saturated aqueous sodium chloride and then dried. Evaporation of the solvent in vacuo yielded 3.6 g. of 4-(di-n-propyl)amino-1,2,2a,3,4,5-hexahydrobenz[cd]indole formed in the above reaction.

Provenance & Evidence