Ammonia → (R)-diethyl 2-t-butyloxycarbonylamino-2-carbamoylsuccinate

A solution of (R)-1-ethyl hydrogen 3-t-butyloxycarbonylamino-3-ethoxycarbonylsuccinate (1.0 g) obtained in Example 14 in THF (20 mL) was added with triethylamine (0.62 mL) and isobutyl chloroformate (0.55 mL, 0.57 g) in this order at −15° C. with stirring, and the mixture was stirred for 30 minutes. A solution of 25% aqueous ammonia (0.30 mL) was dropped into the reaction mixture at the same temperature. The reaction mixture was stirred at the same temperature for 30 minutes, and then poured into diluted hydrochloric acid, the mixture was extracted with ethyl acetate, and then 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 (0.67 g, yield: 73%) as colorless crystals. Optical rotation [α]D22 was +2.74° (c 0.50, ethanol).

1. stirringthe mixture was stirred for 30 minutes
2. stirringThe reaction mixture was stirred at the same temperature for 30 minutes
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

ORD record

ord-40ba259b1ed04ca7a56d61998e2d3d39

Source dataset

uspto-grants-2016_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09434737B2