Hydrochloric Acid → 6-(Piperidin-4-ylidenemethyl)-1,3-dihydroindol-2-one

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Reaction Steps

Dimethyl 2-[4-(1-tert-butoxycarbonylpiperidin-4-ylidenemethyl)-2-nitrophenyl]malonate (1.65 g; 3.7 mmol) was dissolved in ethanol (50 ml), tin powder (1.31 g; 11 g atom) was added followed by conc. hydrochloric acid (10 ml) and the mixture heated at reflux for 3 h before being left to stand at ambient temperature for 18 h. Evaporated to dryness under reduced pressure, water added to the residue and the insoluble material removed by filtration. The filtrate and washings were combined and evaporated to dryness under reduced pressure and this residue extracted with hot methanol. The insoluble materials were further extracted with hot ethanol, the extracts combined and evaporated to dryness under reduced pressure to give the title compound (680 mg; 81%) as a brown foam.

Provenance & Evidence