Acetic Acid → Ethyl 2-(1-benzylpiperidin-4-ylidene)-2-cyanoacetate

Participants

Reaction Steps

N-Benzylpiperidin-4-one (25 g), ethyl cyanoacetate (16.4 g), glacial acetic acid (6 ml) and ammonium acetate (2.54 g) were heated together in toluene (200 ml), with removal of water using a Dean and Stark apparatus, for 90 minutes. The mixture was cooled, a further amount of toluene (100 ml) added and the solution washed sequentially with water (100 ml) and brine (100 ml) at which point a red oily product precipitated. The phases were separated and the oily product dissolved in dichloromethane. The toluene and dichloromethane solutions were combined and the solvents removed under reduced pressure to give a residue. The residue was dissolved in dichloromethane and washed sequentially with water and saturated aqueous sodium hydrogen carbonate solution before removal of the solvent under reduced pressure. The crude product was chromatographed on silica gel eluting with 98:2, by volume, dichloromethane:methanol to give the title compound (30.8 g) as an oil.

Provenance & Evidence