反应详情

A solution of (R)-1-ethyl hydrogen 3-benzyloxycarbonylamino-3-ethoxycarbonylsuccinate (1.8 g) in THF (20 mL) was added with triethylamine (0.96 mL) and isobutyl chloroformate (0.84 mL, 0.87 g) in this order at −15° C. with stirring, and the mixture was stirred for 5 minutes. A solution of 25% aqueous ammonia (0.47 mL) was dropped into the reaction mixture at the same temperature. The reaction mixture was stirred at the same temperature for 1 hour, and then poured into diluted hydrochloric acid, the mixture was extracted with ethyl acetate, and the extract was dried over anhydrous magnesium sulfate. The solvent was evaporated under reduced pressure, and the residue was subjected to silica gel column chromatography, in which elution was performed with n-hexane/ethyl acetate (1:1) for purification, and then crystallized from ethyl acetate/n-hexane to obtain the title compound (1.51 g, yield: 84%) as colorless crystals. Optical rotation [α]D25 was −5.7° (c 0.52, ethanol) and optical purity was 96.1% ee.

1. stirringthe mixture was stirred for 5 minutes
2. stirringThe reaction mixture was stirred at the same temperature for 1 hour
3. extractionthe mixture was extracted with ethyl acetate
4. dry with materialthe extract was dried over anhydrous magnesium sulfate
5. customThe solvent was evaporated under reduced pressure
6. washthe residue was subjected to silica gel column chromatography, in which elution
7. customwas performed with n-hexane/ethyl acetate (1:1) for purification
8. customcrystallized from ethyl acetate/n-hexane