反应详情

A mixture of ethyl 2-(2,3-dihydro-1,4-oxathiin-6-yl)-2-methoxyiminoacetate (16 g.), methanol (160 ml.) and a 1 N aqueous solution (85 ml.) of sodium hydroxide was stirred at room temperature for 25 minutes. The resultant solution was adjusted to pH 4.5 with 10% hydrochloric acid and concentrated at 40° C. in vacuo. To the residue was added ethyl acetate, and the solution was adjusted to pH 7.5 with a saturated aqueous solution of sodium bicarbonate, and then shaken sufficiently. The organic layer was separated and extracted with a saturated aqueous solution of sodium bicarbonate. The extract and the aqueous layer were combined together 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 then dried over magnesium sulfate. After the solution was concentrated in vacuo, the residue was washed with diisopropyl ether to give 2-(2,3-dihydro-1,4-oxathiin-6-yl)-2-methoxyiminoacetic acid (anti isomer, 3.5 g.), yellow crystals, mp. 108° to 110° C. (dec.).

1. concentrationconcentrated at 40° C. in vacuo
2. additionTo the residue was added ethyl acetate
3. customThe organic layer was separated
4. extractionextracted with a saturated aqueous solution of sodium bicarbonate
5. extractionThe extract
6. extractionThe solution was extracted with ethyl acetate
7. washthe extract was washed with water
8. dry with materialdried over magnesium sulfate
9. concentrationAfter the solution was concentrated in vacuo
10. washthe residue was washed with diisopropyl ether