Indole → 3-(1,2,3,6-Tetrahydropyridin-4-yl)-1H-indole

Participants

Reaction Conditions

Reaction Steps

50 ml of N aqueous phosphoric acid and 39.3 g of 4-piperidine-monohydrate hydrochloride were added with stirring under nitrogen to a solution of 10 g of indole in 200 ml of acetic acid heated at 95°-100° C and the mixture was heated for an hour at 100° C and then allowed to cool. The mixture was poured into 350 ml of concentrated ammonium hydroxide containing ice and the mixture was extracted with ethyl acetate. The organic extracts were washed with water and water containing sodium chloride, were dried over magnesium sulfate and evaporated to dryness to obtain 14.7 g of raw product. The latter was crystallized from 75 ml of methanol and the mixture was filtered under reduced pressure. The product was washed with methanol and ether to obtain 1.42 g of 4-([1H]-indol-3-yl)-1,2,3,6-tetrahydro-pyridine melting at 185°-186° C.

Provenance & Evidence