Pyridine → 5-Chloro-2-(4-piperidinyl)-1H-indole

Participants

Reaction Conditions

Reaction Steps

A mixture of 0.60 gm (3.4 mMol) 4-chlorophenylhydrazine hydrochloride and 0.54 mL (6.7 mMol) pyridine in 20 mL ethanol were stirred at 60° C. for 15 minutes. To this mixture was then added 4-acetylpiperidine hydrochloride and the reaction mixture was stirred for 2 hours at 70° C. The reaction mixture was concentrated under reduced pressure and the residue was treated with polyphosphoric acid. This mixture was heated at 90-100° C. for 48 hours. The reaction mixture was quenched with a slurry of ice in 5N sodium hydroxide. The aqueous mixture was extracted well with ethyl acetate. The organic phases were combined, washed with saturated aqueous sodium chloride, dried over sodium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel chromatography, eluting with a dichloromethane gradient containing 4-20% methanol. Fractions containing product were combined and concentrated under reduced pressure to provide 0.26 gm (36%) of the title compound as a tan solid.

Provenance & Evidence