Reaktion #3851

Reaktionsgleichung

sodium hydroxide

toluene acetic acid

( a )

(±)-3-[[2-[(Acetylthio)methyl]-1-oxo-3-phenylpropyl]amino]propanoic acid, ethyl ester

sodium hydroxide

→

(±)-3-[[2-(Mercaptomethyl)-1-oxo-3-phenylpropyl]amino]propanoic acid

Lösungsmittel

methanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONis added in one portion
2. 2
   workup.STIRRINGAfter stirring for an additional 3 hours at room temperature
3. 3
   Einengenthe mixture is concentrated to approximately 1/2 volume in vacuo
4. 4
   Sonstigethe residue is partitioned between water (50 ml.) and ethyl acetate (30 ml.)
5. 5
   WaschenThe aqueous layer is washed with ethyl acetate (30 ml.)
6. 6
   Extraktionextracted again with ethyl acetate (3×20 ml.)
7. 7
   Waschenwashed with water and brine (30 ml
8. 8
   Trockneneach), dried (Na2SO4)
9. 9
   Einengenconcentrated in vacuo
10. 10
    Sonstigeto yield 0.71 g

Vorschrift

A solution of the product from part (a) (1.02 g., 3.02 mmole) in methanol (6 ml.) is chilled (ice/methanol) and to it, under nitrogen, is added 1N sodium hydroxide (6.35 ml.) over 15 minutes. The mixture is stirred for 3 hours while warming to room temperature (TLC indicates incomplete reaction), and additional 1N sodium hydroxide (3.0 ml.) is added in one portion. After stirring for an additional 3 hours at room temperature, the mixture is concentrated to approximately 1/2 volume in vacuo, and the residue is partitioned between water (50 ml.) and ethyl acetate (30 ml.). The aqueous layer is washed with ethyl acetate (30 ml.), adjusted to a pH of about 2 with concentrated hydrochloric acid, and extracted again with ethyl acetate (3×20 ml.). These organic layers are pooled, washed with water and brine (30 ml. each), dried (Na2SO4), and concentrated in vacuo to yield 0.71 g. of (±)-3-[[2-(mercaptomethyl)-1-oxo- -phenylpropyl]amino]propanoic acid as a white solid; m.p. 76°-82°. TLC (silica gel, toluene/acetic acid; (4:1) Rf =0.37, minor spot at 0.07.

Quelle