Potassium Hydroxide → 5-chloro-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole

Participants

Reaction Steps

A mixture of 15.1 g of 5-chloro-1H-indole, 30.7 g of the hydrate of 4-piperidone hydrochloride and 150 ml of 2 N methanolic potassium hydroxide solution was refluxed under an inert atmosphere for 71/2 hours and was allowed to stand overnight at room temperature. The mixture was poured into 1.5 liters of water and the mixture was extracted with ethyl acetate. The organic phase was washed with water, aqueous sodium chloride solution, was dried over magnesium sulfate and evaporated to dryness. The 20.5 g of residue were dissolved in 1 liter of refluxing benzene and the solution was filtered hot. The solution was cooled to induce crystallization and after 3 hours, the mixture was vacuum filtered. The recovered product was rinsed with benzene to obtain 10.2 g of 5-chloro-3-(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole melting at 177° C. The mother liquors were concentrated and crystallization induced to obtain 2.49 g of the said product melting at 175°-177° C. for a total yield of 12.69 g. For analysis, the product was purified by salification with an acid and then return to the basis.

Provenance & Evidence