反应详情

To a solution of tert-butyl (3R)-4-hydroxy-3-methyl-5-oxo-1-[(1R)-1-phenylethyl]pyrrolidine-3-carboxylate (9.35 g, 29.3 mmol) in tetrahydrofuran (150 mL), a solution of borane in tetrahydrofuran (82.6 mL, 96.6 mmol, 1.17M solution in tetrahydrofuran) was added in an ice bath, and the mixture was stirred room temperature for 14 hours. Water (20 mL), ethanol (80 mL), and triethylamine (20 mL) were added to the reaction mixture in an ice bath, and the mixture was heated under reflux in an oil bath at 88° C. for 2 hours. After concentrating the reaction mixture under reduced pressure, water (200 mL) was added and the mixture was extracted with ethyl acetate (200 mL×2). The organic layer was washed with saturated aqueous solution of sodium chloride (200 mL), and dried with anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure, and the residue was purified by silica gel column chromatography (hexane:ethyl acetate=3:1→1:2) to obtain 4.75 g (53.1%) of the title compound as a colorless oily substance.

1. temperaturethe mixture was heated
2. temperatureunder reflux in an oil bath at 88° C. for 2 hours
3. concentrationAfter concentrating the reaction mixture under reduced pressure, water (200 mL)
4. additionwas added
5. extractionthe mixture was extracted with ethyl acetate (200 mL×2)
6. washThe organic layer was washed with saturated aqueous solution of sodium chloride (200 mL)
7. dry with materialdried with anhydrous sodium sulfate
8. customThe solvent was removed by distillation under reduced pressure
9. customthe residue was purified by silica gel column chromatography (hexane:ethyl acetate=3:1→1:2)