反应详情

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.

1. additionis added dropwise over the course of 15 minutes at 0° C.
2. washwashed with water, with dilute hydrochloric acid and again with water
3. dry with materialdried over sodium sulphate
4. concentrationconcentrated by evaporation in vacuo
5. customThe residue is chromatographed on 10 g of acid-washed silica gel