反应详情

A solution of potassium hydroxide (85% assay, 2.69 g, 0.041 mol) and sodium hydroxide (1.94 g, 0.048 mol) in demineralized water (8 mL) is added to a solution of 4-isobutylpiperidine-1,4-dicarboxylic acid-1-tertbutyl ester-4-ethyl ester (0.95 g, 0.003 mol) in ethanol (15 mL). The reaction mixture is refluxed for 48 hrs. It is cooled to room temperature, concentrated under reduced pressure, and then treated with demineralized water (10 mL). The pH is adjusted to ˜3-4 using 2N HCl (10 mL) and the aqueous layer is extracted with ethyl acetate (2×15 mL). The combined extract is dried over sodium sulfate. Removal of solvent gives a crude residue which is purified by column chromatography (230-400 mesh, ethyl acetate:n-hexane 1:3) to furnish 4-isobutylpiperidine-1,4-dicarboxylic acid monotertbutyl ester.

1. temperatureThe reaction mixture is refluxed for 48 hrs
2. concentrationconcentrated under reduced pressure
3. additiontreated with demineralized water (10 mL)
4. extractionthe aqueous layer is extracted with ethyl acetate (2×15 mL)
5. extractionThe combined extract
6. dry with materialis dried over sodium sulfate
7. customRemoval of solvent
8. customgives a crude residue which
9. customis purified by column chromatography (230-400 mesh, ethyl acetate:n-hexane 1:3)