Ethanol → 1-Benzyl 3-ethyl 4-oxopyrrolidine-1,3-dicarboxylate

To a solution of ethyl 3-[N-benzyloxycarbonyl-N-(ethoxycarbonyl methyl)amino]ethylpropionate (26.8 g, 79.5 mmol) in ethanol (200 mL), sodium ethoxide (20% solution in ethanol, 40.6 mL, 119.3 mmol) was added, and the mixture was heated under reflux for 2 hours. After concentrating the reaction mixture under reduced pressure, the residue was dissolved in water (100 mL). Concentrated hydrochloric acid was added to this solution in an ice bath for acidification, and the solution was extracted with chloroform (100 mL×3). The extract was washed with saturated aqueous solution of sodium chloride (100 mL), and dried with anhydrous sodium sulfate. After the filtration, the filtrate was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (hexane:ethyl acetate, 2:1) to obtain 16.7 g (72%) of the title compound as a pale brown oily product.

1. temperaturethe mixture was heated
2. temperatureunder reflux for 2 hours
3. concentrationAfter concentrating the reaction mixture under reduced pressure
4. dissolutionthe residue was dissolved in water (100 mL)
5. additionConcentrated hydrochloric acid was added to this solution in an ice bath for acidification
6. extractionthe solution was extracted with chloroform (100 mL×3)
7. washThe extract was washed with saturated aqueous solution of sodium chloride (100 mL)
8. dry with materialdried with anhydrous sodium sulfate
9. filtrationAfter the filtration
10. concentrationthe filtrate was concentrated under reduced pressure
11. customthe residue was purified by silica gel column chromatography (hexane:ethyl acetate, 2:1)

ORD record

ord-cd8cd79b66024d72bc513730e8fb36cd

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08211910B2