反应详情

A mixture of ethyl 2-(2-bromoethoxyimino)-3-oxobutyrate (syn isomer)(218.9 g), ethylene glycol (156 ml), and benzene (400 ml) was refluxed in the presence of p-toluenesulfonic acid monohydrate under an azeotropic dehydration condition for 3 days. The mixture was poured into a mixture of ethyl acetate and saturated aqueous solution of sodium bicarbonate under ice-cooling. The organic layer was separated, washed with water, dried over magnesium sulfate and concentrated in vacuo to give a residue. The resiue was distilled at 2 mmHg at 144° to 149° C. to give ethyl 2-(2-bromoethoxyimino)3,3-ethylenedioxybutyrate (syn isomer)(333.3 g) as an oil.

1. temperaturecooling
2. customThe organic layer was separated
3. washwashed with water
4. dry with materialdried over magnesium sulfate
5. concentrationconcentrated in vacuo
6. customto give a residue
7. distillationThe resiue was distilled at 2 mmHg at 144° to 149° C.