反应详情

Sodium borohydride (465 mg) was added to a solution of (3S)-5-oxo-3-(2-oxoethyl)-1-[(1R)-1-phenylethyl]pyrrolidine-3-carboxylic acid tert-butyl ester (2.71 g, 8.19 mmol) in methanol at −40° C. After heating to room temperature, a 10% citric acid solution was added to the reaction solution, and the mixture was stirred. The reaction solution was poured into a mixture of ethyl acetate (50 mL) and a 10% citric acid solution (10 mL), followed by extraction with ethyl acetate (100 mL). The aqueous layer was extracted with ethyl acetate (100 mL), and then the organic layers were combined and washed with brine (50 mL×2). The resulting organic layer was dried over anhydrous sodium sulfate and filtered, and then the filtrate was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (hexane:ethyl acetate=2:1→1:1→0:1→ethyl acetate-methanol=10:1) to give 2.20 g (81%) of the title compound as a white solid.

1. extractiona 10% citric acid solution (10 mL), followed by extraction with ethyl acetate (100 mL)
2. extractionThe aqueous layer was extracted with ethyl acetate (100 mL)
3. washwashed with brine (50 mL×2)
4. dry with materialThe resulting organic layer was dried over anhydrous sodium sulfate
5. filtrationfiltered
6. concentrationthe filtrate was concentrated under reduced pressure
7. customThe resulting residue was purified by silica gel column chromatography (hexane:ethyl acetate=2:1→1:1→0:1→ethyl acetate-methanol=10:1)