反应详情

A benzene solution (90 mL) of ethyl-3-methyl-2-oxobutanoate (4.03 g, 28.0 mmol), methyl carbamate (2.098 g, 28.0 mmol) and pyridine 4-methylbenzenesulfonate (0.70 g, 2.80 mmol) was heated to reflux in a round bottom flask equipped with a Dean-Stark trap and reflux condenser. After 44 hours of heating the mixture was cooled and then partitioned between ethyl acetate (50 mL) and brine (50 mL). The organic phase was washed with brine (2×50 mL) then dried (MgSO4) and concentrated in vacuo. The crude product was purified by chromatography on silica gel (ethyl acetate-hexanes) to provide the title compound as an off white crystalline solid (1.487 g, 26%).

1. temperatureto reflux in a round bottom flask
2. customequipped with a Dean-Stark trap
3. temperaturereflux condenser
4. temperatureAfter 44 hours of heating the mixture
5. temperaturewas cooled
6. custompartitioned between ethyl acetate (50 mL) and brine (50 mL)
7. washThe organic phase was washed with brine (2×50 mL)
8. dry with materialthen dried (MgSO4)
9. concentrationconcentrated in vacuo
10. customThe crude product was purified by chromatography on silica gel (ethyl acetate-hexanes)