反应详情

Cis-2-methyl-N-phenyl-1,3-oxathiolane-2-acetamide-3-oxide, prepared from 0.1 moles of 2-methyl-N-phenyl-1,3-oxathiolane-2-acetamide as prepared in Example 1, was placed with toluene (100 g), tetrabutylammonium bromide (a phase transfer catalyst) (0.32 g, 0.001 g mole) and malonic acid (pKa =2.83, 0.41 g, 0.004 g mole) in a 1 L three-necked round bottom flask equipped with a mechanical stirrer, a thermometer and a Dean-Stark trap for the efficient removal of evolved water of reaction. The reaction mixture so prepared was placed under a vacuum equivalent of 300 mm of Hg and heated at 72°-75° C. for 1 hour. Methanesulfonic acid (0.19 g, 0.002 g mole) was then added to the reaction mixture, the vacuum was increased to 200 mm Hg and heating was continued at 72°-75° C. for an additional hour. The reaction mixture was then cooled to 55°-60° C. and washed successively with 100 mL portions of 5% aqueous sodium hydroxide solution and water. The resulting organic layer was then decanted and concentrated, and after isolation and drying, yielded a total of 17.3 g of 5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide.

1. customas prepared in Example 1
2. customequipped with a mechanical stirrer
3. customa thermometer and a Dean-Stark trap for the efficient removal of evolved water of reaction
4. customThe reaction mixture so prepared
5. temperatureheated at 72°-75° C. for 1 hour
6. temperaturethe vacuum was increased to 200 mm Hg
7. temperatureheating
8. waitwas continued at 72°-75° C. for an additional hour
9. temperatureThe reaction mixture was then cooled to 55°-60° C.
10. washwashed successively with 100 mL portions of 5% aqueous sodium hydroxide solution and water
11. customThe resulting organic layer was then decanted
12. concentrationconcentrated
13. customafter isolation and drying