反应详情

1 N Aqueous solution (24 ml.) of sodium hydroxide was added to a solution of ethyl 2-(2,3-dihydro-1,4-oxathiin-6-yl)-2-methoxyiminoacetate (syn isomer, 4.6 g.) in methanol (50 ml.), and stirred at room temperature for 16 hours. After the resultant solution was concentrated in vacuo, the residue was dissolved in water. The solution was washed with ethyl acetate and adjusted to pH 1.0 with 10% hydrochloric acid. The solution was extracted with ethyl acetate, and the extract was washed with water and dried over magnesium sulfate. The solution was concentrated under reduced pressure at 40° C., and the residue was washed with diisopropyl ether and then dried to give 2-(2,3-dihydro-1,4-oxathiin-6-yl)-2-methoxyiminoacetic acid (syn isomer, 3.8 g.), white crystals, mp. 129° to 131° C. (dec.).

1. concentrationAfter the resultant solution was concentrated in vacuo
2. dissolutionthe residue was dissolved in water
3. washThe solution was washed with ethyl acetate
4. extractionThe solution was extracted with ethyl acetate
5. washthe extract was washed with water
6. dry with materialdried over magnesium sulfate
7. concentrationThe solution was concentrated under reduced pressure at 40° C.
8. washthe residue was washed with diisopropyl ether
9. customdried