反应详情

The procedure found in J. Am. Chem. Soc. 75, 2377-9 (1953) was generally followed. Ethyl isodehydroacetate (100 g, 0.51 mol) was added to a warm solution of sodium hydroxide (68.5 g., 0.71 mol) in water (500 mL) and stirred for an hour until the mixture became clear. The solution was acidified with concentrated hydrochloric acid (200 mL) and was extracted with ethyl acetate. The extract was dried over magnesium sulfate and concentrated by evaporation under reduced pressure. The residue was mixed with acetic anhydride (250 mL) and the resulting mixture was heated at reflux for 20-30 min. The solvent was removed by evaporation under reduced pressure and the residue obtained was crystallized from ether to obtain 60.8 g (94 percent of theory) of the title compound as a tan powder melting at 70°-72° C.

1. extractionwas extracted with ethyl acetate
2. dry with materialThe extract was dried over magnesium sulfate
3. concentrationconcentrated by evaporation under reduced pressure
4. additionThe residue was mixed with acetic anhydride (250 mL)
5. temperaturethe resulting mixture was heated
6. temperatureat reflux for 20-30 min
7. customThe solvent was removed by evaporation under reduced pressure
8. customthe residue obtained
9. customwas crystallized from ether