Reaktion #94922

Reaktionsgleichung

trimethylchlorosilane

sodium cephalothin

monosilyltrifluoroacetamide

2-thienylacetyl chloride

→

7-(di-2-thienylacetyl)amino-3-acetoxymethyl-3-cephem-4-carboxylic acid

Lösungsmittel

chloroform

—

alcohol

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITto remain at this temperature for two days
2. 2
   Sonstigeevaporated in vacuo to a residue which
3. 3
   workup.DISSOLUTIONis dissolved in ethyl acetate (50 ml.)
4. 4
   Waschenwashed three times with water
5. 5
   TrocknenThe ethyl acetate layer is dried over magnesium sulfate
6. 6
   Filtrationfiltered
7. 7
   Sonstigethe filtrate evaporated in vacuo
8. 8
   Sonstigeto obtained a residue
9. 9
   Sonstigeprecipitated with hexane three times

Vorschrift

A suspension of sodium cephalothin (1.18 g.) in anhydrous alcohol-free chloroform (10 ml.) is silylated by the addition of trimethylchlorosilane (1.1 ml.). After stirring for 30 minutes, monosilyltrifluoroacetamide (2.5 ml.) and 2-thienylacetyl chloride (2.0 ml.) are added to the suspension which is then heated to 45° C. The mixture is allowed to remain at this temperature for two days and then evaporated in vacuo to a residue which is dissolved in ethyl acetate (50 ml.) and washed three times with water. The ethyl acetate layer is dried over magnesium sulfate, filtered and the filtrate evaporated in vacuo to obtained a residue. The residue is dissolved in chloroform and precipitated with hexane three times, each time discarding the supernatent liquid. The 7-(di-2-thienylacetyl)amino-3-acetoxymethyl-3-cephem-4-carboxylic acid is obtained in a solvent-free form by freeze-drying from a solution in benzene.

Quelle