Reacción #94922

Ecuación de reacción

trimethylchlorosilane

sodium cephalothin

monosilyltrifluoroacetamide

2-thienylacetyl chloride

→

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

Disolventes

chloroform

—

alcohol

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.WAITto remain at this temperature for two days
2. 2
   Otroevaporated in vacuo to a residue which
3. 3
   workup.DISSOLUTIONis dissolved in ethyl acetate (50 ml.)
4. 4
   Lavadowashed three times with water
5. 5
   SecadoThe ethyl acetate layer is dried over magnesium sulfate
6. 6
   Filtraciónfiltered
7. 7
   Otrothe filtrate evaporated in vacuo
8. 8
   Otroto obtained a residue
9. 9
   Otroprecipitated with hexane three times

Procedimiento

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.

Fuente