反应详情

A mixture of 2,4-dioxopiperidine (15.1 g), methyl orthoformate (30 ml) and p-toluenesulfonic acid (3.0 g) in methanol (300 ml) is refluxed for 1 hour. After evaporating the solvent, the residue is dissolved in benzene and refluxed for 5 hours. To the solution is added potassium carbonate (9.0 g), and the mixture is stirred overnight at room temperature and then filtered. The filtrate is distilled to remove the solvent. The residue is recrystallized from ethyl acetate-isopropyl alcohol to give 4-methoxy-5,6-dihydro-2(1H)-pyridone (12.3 g, 72.5%) as colorless prisms. m.p. 115°-117° C.

1. temperatureis refluxed for 1 hour
2. customAfter evaporating the solvent
3. dissolutionthe residue is dissolved in benzene
4. temperaturerefluxed for 5 hours
5. additionTo the solution is added potassium carbonate (9.0 g)
6. filtrationfiltered
7. distillationThe filtrate is distilled
8. customto remove the solvent
9. customThe residue is recrystallized from ethyl acetate-isopropyl alcohol