Piperidine → 4-[(1Z)-3-[(2S)-1-(tert-Butoxycarbonyl)pyrrolidinyl]-2-(ethoxycarbonyl)-3-oxo-1-propenyl]benzoic acid

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Reaction Steps

To a solution of tert-butyl (2S)-2-(3-ethoxy-3-oxopropanoyl)-1-pyrrolidinecarboxylate (5.0 g, 17.5 mmol) in benzene (50 ml) and piperidine (0.3 ml, 3 mmol) was added 4-carboxybenzaldehyde (2.63 g, 17.5 mmol), and the mixture was refluxed for 3 h. The cooled solution was washed with 0.1 N HCl twice. The aqueous layer was extracted three times with ether. The combined organic phases were dried (Na2SO4) and concentrated to give C as a tan solid (5.54 g, 76% yield). LCMS m/z 416 (M−H), 833 (2M−H).

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