Hydrochloric Acid → (S)-tert-butyl 2-((tert-butoxycarbonyl)amino)-5-hydroxypentanoate

Temperature

-10 °C

To a solution of N-(t-butoxycarbonyl)-L-glutamic acid t-butyl ester (6.0 g, 19.78 mmol) and triethylamine (2.83 mL, 20.27 mmol) in THF at −10° C. is added ethyl chloroformate (1.94 mL, 20.27 mmol) dropwise, via syringe, and the solution is stirred at −10° C. for 30 minutes. The solution is filtered to remove precipitate, and the filtrate is added into a solution of NaBH4 (2.3 g, 60.86 mmol) in THF (40 mL) and water (50 mL). This solution is then stirred for 4 hours, after which time the solution is acidified with 1 N HCl to pH=5, and THF is evaporated. The aqueous residue is extracted with EtOAc (3×200 mL), and the organic layers is then washed with 1 N NaOH (2×300 mL), water (300 mL) and brine (300 mL), dried over MgSO4, and evaporated. Chromatography (silica, 20% EtOAc/hexane) yields t-butyl (S)-5-hydroxy-2-(t-butoxycarbonylamino)-pentanoate as a thick oil.

1. filtrationThe solution is filtered
2. customto remove precipitate
3. stirringThis solution is then stirred for 4 hours
4. customis evaporated
5. extractionThe aqueous residue is extracted with EtOAc (3×200 mL)
6. washthe organic layers is then washed with 1 N NaOH (2×300 mL), water (300 mL) and brine (300 mL)
7. dry with materialdried over MgSO4
8. customevaporated

ORD record

ord-a129c80edc2347bd87316c59ef04d80c

Source dataset

uspto-grants-2002_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06353017B1