Reaktion #214636

Reaktionsgleichung

2-[4-(p-toluenesulphonylthio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-methylene-butyric acid p-nitrobenzyl ester

sodium bisulphite

→

2-[4-(p-toluenesulphonylthio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-hydroxy-crotonic acid p-nitrobenzyl ester

Lösungsmittel

ethyl acetate

methyl acetate

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeozonised at -70° C.
2. 2
   Temperaturthe latter is warmed to 0°-5° C
3. 3
   Sonstigethe aqueous phase is separated off
4. 4
   Waschenthe organic phase is washed with water
5. 5
   Trocknendried over magnesium sulphate
6. 6
   workup.DISSOLUTIONThe crude product is dissolved in 3 ml of methylene chloride
7. 7
   workup.ADDITION15 ml of toluene are added
8. 8
   FiltrationThe precipitate is filtered off
9. 9
   Einengenthe filtrate is concentrated by evaporation in vacuo
10. 10
    SonstigeThe residue is recrystallised from methanol

Vorschrift

(di) The crude 2-[4-(p-toluenesulphonylthio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-methylene-butyric acid p-nitrobenzyl ester obtained according to Example (1.cvii) is dissolved in 20 ml of methyl acetate and ozonised at -70° C. until starting material is no longer present, according to a thin layer chromatogram. A stream of nitrogen is then passed through the solution and the latter is warmed to 0°-5° C. A solution of 300 mg of sodium bisulphite in 5 ml of water is added and the mixture is stirred for about 5 minutes until no further ozonide is detectable by means of potassium iodide/starch paper. The mixture is diluted with ethyl acetate, the aqueous phase is separated off and the organic phase is washed with water, dried over magnesium sulphate and freed from the solvent in vacuo. The crude product is dissolved in 3 ml of methylene chloride and 15 ml of toluene are added. The precipitate is filtered off and the filtrate is concentrated by evaporation in vacuo. The residue is recrystallised from methanol and gives 2-[4-(p-toluenesulphonylthio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-hydroxy-crotonic acid p-nitrobenzyl ester of melting point 159°-160° C.

Quelle