Hydrochloric Acid → 3-(1,2,5,6-Tetrahydropyridyl)pyrrolopyridine

Participants

Reaction Steps

To a stirred solution of Na (2.53 g, 110 mmol, 11 eq) in absolute methanol (50 ml) at room temperature was added the appropriate pyrrolopyridine (10.00 mmol) and piperidone monohydrate hydrochloride (4.60 g, 30.0 mmol, 3.0 eq). The resultant mixture was then heated at reflux under nitrogen for 2-24 hours depending on the substrate. The resultant reaction mixture was cooled, and concentrated hydrochloric acid (37%, 9.0 ml, 110 mmol) was added dropwise with vigorous stirring. The resultant mixture was then evaporated under reduced pressure, and the residual slurry placed in water (50 ml). This aqueous mixture was extracted with ethyl acetate (5×50 ml), and these extracts were combined, dried (Na2SO4), and evaporated under reduced pressure. The residue was either triturated directly or column chromatographed using silica gel (approximately 100 g) and elution with the appropriate solvent system yielding the desired 3-(1,2,5,6-tetrahydropyridyl)pyrrolopyridine, one of Compounds 1a-1m or compound 2, 3a, 3b, 3c or 4.

Provenance & Evidence