Reaktion #1770526

Reaktionsgleichung

hydrochloric acid

3-(3-Thienyl)-L-alanine

Sodium carbonate

N-Carbethoxyphthalimide

→

title compound

N-Phthalimido-3-(3-thienyl)-L-alanine

Lösungsmittel

water p-dioxane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGthe resulting mixture was stirred for 3.0 hours
2. 2
   Extraktionthe mixture was extracted with ethyl acetate
3. 3
   WaschenThe organic layer was washed successively with 10% potassium bisulfate and brine
4. 4
   Trocknendried (sodium sulfate)
5. 5
   Filtrationfiltered
6. 6
   Einengenconcentrated
7. 7
   Sonstigechromatographed (Merck silica gel)
8. 8
   Wascheneluting with 1:1 ethyl acetate/hexane/1% acetic acid
9. 9
   workup.ADDITIONThe fractions containing clean desired product
10. 10
    Einengenconcentrated
11. 11
    Sonstigeazeotroped with ethyl acetate
12. 12
    Waschenwashed with water
13. 13
    Sonstigeto remove the acetic acid
14. 14
    TrocknenThe organic layer was dried (sodium sulfate)
15. 15
    Filtrationfiltered
16. 16
    Einengenconcentrated
17. 17
    Sonstigeto give 3.22 g

Vorschrift

3-(3-Thienyl)-L-alanine (2.45 g., 14.3 mmol.) was suspended in water/p-dioxane (22 ml/11 ml.) at room temperature under argon. Sodium carbonate (1.52 g.) was added and the mixture was stirred until homogeneous. N-Carbethoxyphthalimide (3.14 g.) was added, and the resulting mixture was stirred for 3.0 hours and then cooled to 0° C. The pH was adjusted to 1.5 with 6 N hydrochloric acid and the mixture was extracted with ethyl acetate. The organic layer was washed successively with 10% potassium bisulfate and brine, dried (sodium sulfate), filtered, and concentrated. The crude product was flash chromatographed (Merck silica gel) eluting with 1:1 ethyl acetate/hexane/1% acetic acid. The fractions containing clean desired product were combined, concentrated, azeotroped with ethyl acetate, and washed with water to remove the acetic acid. The organic layer was dried (sodium sulfate), filtered, and concentrated to give 3.22 g. of title compound as a white crystalline product; m.p. 166°-168° C.; [α]D =-146.8° (c=0.46, methylene chloride). TLC (1% acetic acid in 1:1 ethyl acetate/hexane) Rf =0.31.

Quelle