L-Alanine → N-carbobenzyloxyalanine

HRID 568989Notes

Reaction equation

HRID 568989 reaction equation
[C:1](Cl)([O:3][CH2:4][C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1)=[O:2].[NH2:12][C@H:13]([C:15]([OH:17])=[O:16])[CH3:14]>[OH-].[Na+]>[CH2:4]([O:3][C:1]([NH:12][C@H:13]([C:15]([OH:17])=[O:16])[CH3:14])=[O:2])[C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1

Participants

4

Reactant 2

HCID 5950L-AlanineHCID 10387Benzyl chloroformate

Product 1

HCID 736104N-carbobenzyloxyalanineYield 73%

Reagents, catalysts & solvents 1

HCID 14798Sodium HydroxideSolvent2×

Conditions

Temperature
0 °C

Procedure

In a 2 L three-necked flask, L-alanine (54.0 g) is dissolved in 2N NaOH (305 mL) and cooled to 0° C. in an ice-bath. To this solution, carbobenzoxychloride (90 mL) and 2N NaOH (305 mL) are simultaneously added dropwise so that the reaction temperature does not exceed 5° C. After complete addition, the ice-bath is removed and the reaction mixture stirred for 2 hours at room temperature. Diethylether is added (100 mL) and the organic phase is separated. The aqueous phase is washed once more with Et2O (100 mL), and acidified to pH 1 with HCl (2N). Ethylacetate (150 mL) is added, and the organic phase is separated. The aqueous phase is extracted with AcOEt (3×150 mL), and the combined organic phases are washed with H2O (3×100 mL). After drying (MgSO4), the solvent is removed (20 Torr/30° C.) to leave a colorless oil, which crystallizes upon standing (110 g). Recrystallization (AcOEt/hexane) affords 100 mg (73%) of benzyloxycarbonyl-L-alanine, m.p. 85° C.; [α]23 =-14.3 (c=2 in AcOH).

Workup

  1. customdoes not exceed 5° C
  2. additionAfter complete addition
  3. customthe ice-bath is removed
  4. additionDiethylether is added (100 mL)
  5. customthe organic phase is separated
  6. washThe aqueous phase is washed once more with Et2O (100 mL)
  7. additionEthylacetate (150 mL) is added
  8. customthe organic phase is separated
  9. extractionThe aqueous phase is extracted with AcOEt (3×150 mL)
  10. washthe combined organic phases are washed with H2O (3×100 mL)
  11. dry with materialAfter drying (MgSO4)
  12. customthe solvent is removed (20 Torr/30° C.)
  13. customto leave a colorless oil, which
  14. customcrystallizes
  15. customRecrystallization (AcOEt/hexane)

Sources & evidence

ORD record
ord-df9c48d6d226404e98643b882136516e
Source dataset
uspto-grants-1988_03
Patent number
US04730006

Reaction notes

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