Reaktion #54382

Reaktionsgleichung

2-[4-(benzthiazol-2-yldithio)-3-phenoxyacetamido-2-oxoazetidin-1-yl ]-3-methoxy-crotonic acid chloride

triethylamine

tert.-butanol

2-[4-(benzthiazol-2-yldithio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-methoxy-isocrotonic acid chloride

→

7β-Phenoxyacetamido-3-methoxy-ceph-2-em-4-carboxylic acid tert.butyl ester

Lösungsmittel

methylene chloride

methylene chloride

methylene chloride

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONis added dropwise over the course of 15 minutes at 0° C.
2. 2
   Waschenwashed with water, with dilute hydrochloric acid and again with water
3. 3
   Trocknendried over sodium sulphate
4. 4
   Einengenconcentrated by evaporation in vacuo
5. 5
   SonstigeThe residue is chromatographed on 10 g of acid-washed silica gel

Vorschrift

A solution of 266 mg (0.5 mM) of a crude mixture consisting of 2-[4-(benzthiazol-2-yldithio)-3-phenoxyacetamido-2-oxoazetidin-1-yl ]-3-methoxy-crotonic acid chloride and 2-[4-(benzthiazol-2-yldithio)-3-phenoxyacetamido-2-oxoazetidin-1-yl]-3-methoxy-isocrotonic acid chloride in 5 ml of dry methylene chloride is added dropwise over the course of 15 minutes at 0° C., whilst stirring, to a solution of 0.10 ml of triethylamine in 0.5 ml of dry tert.-butanol and 3 ml of methylene chloride. After a further 15 minutes stirring, the reaction mixture is diluted with methylene chloride, washed with water, with dilute hydrochloric acid and again with water, dried over sodium sulphate and concentrated by evaporation in vacuo. The residue is chromatographed on 10 g of acid-washed silica gel, using toluene/ethyl acetate (4:1) as the running agent. 7β-Phenoxyacetamido-3-methoxy-ceph-2-em-4-carboxylic acid tert.butyl ester is obtained. IR spectrum (in CH2CL2): characteristic bands at 5.60, 5.77, 5.90 and 8.29 μ.

Quelle