L-Proline → 4-[1,8]Naphthyridin-2-yl-piperidine-1-carboxylic acid benzyl ester

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Reaction Steps

100 mg (0.383 mmol) ketone (21), 47 mg (0.383 mmol) 2-aminopyridine-3-carbaldehyde and 22 mg (0.192 mmol) proline were refluxed in ethanol for 3 days. The solvent was removed under reduced pressure. The crude product was purified by chromatography on silica gel (ethyl acetate/hexane) to yield 4-[1,8]naphthyridin-2-yl-piperidine-1-carboxylic acid benzyl ester as an oil. 210 mg (0,605 mmol) of this intermediate were dissolved together with 50 mg 10% Pd/C in 50 ml methanol and stirred under an atmosphere of hydrogen for 18 h. Removal of the catalyst by filtration through a pad of Celite followed by evaporation of the solvent under reduced pressure gave the desired amine (22).

Provenance & Evidence