反应详情

The crude (RS)-1-(4-hydroxyphenyl)-5-oxo-pyrrolidine-3-carboxylic acid was 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 for 2 h. The reaction solution was reduced to half of its volume by distillation, then transferred into a 20 l vessel. Under stirring at 40° C., a mixture of 2500 ml of water/ice (1:1) was added. Crystallisation started immediately, and, thereupon, the fine white crystals were collected on a filter funnel. They were washed with a total of 2000 ml of cold water until the filtrate was neutral. The product was dried under reduced pressure to yield 980 g (84% of theory, 2 steps) of (RS)-1-(4-hydroxyphenyl)-5-oxo-pyrrolidine-3-carboxylic acid methyl ester as a white solid; MS: m/e=234 (M+H)+.

1. temperatureunder reflux for 2 h
2. distillationThe reaction solution was reduced to half of its volume by distillation
3. customtransferred into a 20 l vessel
4. stirringUnder stirring at 40° C.
5. additiona mixture of 2500 ml of water/ice (1:1)
6. additionwas added
7. customCrystallisation
8. customthe fine white crystals were collected on a filter funnel
9. washThey were washed with a total of 2000 ml of cold water until the filtrate
10. customThe product was dried under reduced pressure