反应详情

In a 10 1 4-necked flask equipped with a reflux condenser, a thermometer, and a mechanical stirrer, the crude (RS)-1-(4-hydroxyoxy-phenyl)-5-oxo-pyrrolidine-3-carboxylic acid is dissolved in a mixture of 5000 ml of methanol, 24 ml of concentrated sulfuric acid and 400 ml of 2,2-dimethoxypropane and stirred under reflux during 2 h. For the working-up, the reaction solution is reduced to half of its volume by distillation, then transferred into a 20 1 vessel. Under stirring at 40° C., a mixture of 2500 ml of water/ice (1:1) is added. Crystallisation started immediately, and, thereupon, the fine white crystals are collected on a filter funnel. They are washed with total 2000 ml of cold water until the filtrate, at the beginning brownish-rose, becomes colorless and neutral. The well pressed and pre-dried product from the filter funnel is dried under reduced pressure to yield 980 g (84% of theory, 2 steps) of the (RS)-1-(4-hydroxyoxy-phenyl)-5-oxo-pyrrolidine-3-carboxylic acid methyl ester as a white solid; MS: m/e=234 (M+H)+.

1. customIn a 10 1 4-necked flask equipped with a reflux condenser
2. temperatureunder reflux during 2 h
3. distillationthe reaction solution is reduced to half of its volume by distillation
4. stirringUnder stirring at 40° C.
5. additiona mixture of 2500 ml of water/ice (1:1)
6. additionis added
7. customCrystallisation
8. customthe fine white crystals are collected on a filter funnel
9. washThey are washed with total 2000 ml of cold water until the filtrate
10. custompre-dried product from the filter funnel is dried under reduced pressure