反应详情

Zinc powder (0.9 g) was added under ice-cooling to a solution of 2,2,2-trichloroethyl 2-methyl-7-(2-phenylacetamido)-3-cephem-4-carboxylate (0.69 g), mp 120° to 130° C., in a mixture of dimethylformamide (5 ml) and acetic acid (1 ml), and the mixture was stirred for 1.5 hours, followed by filtration of the reaction mixture, after which the filtered zinc was washed with a small amount of dimethylformamide. The filtrate and the washings were combined and the combined solution was poured into a mixture of ethyl acetate (30 ml), water (30 ml) and 10% hydrochloric acid (2 ml), after which the ethyl acetate layer was separated. The aqueous layer was further extracted with ethyl acetate (10 ml). The ethyl acetate layer was combined, and the combined solution was in turn washed with water, a saturated sodium chloride aqueous solution, dried over magnesium sulfate, after which the solvent was distilled off. The residue was crystallized by adding a small quantity of acetonitrile, and the precipitated crystals were collected by filtration and dried to give 2-methyl-7-(2-phenylacetamido)-3-cephem-4-carboxylic acid (0.34 g), mp 121° C., which is an isomer at 2 position of 2-methyl-7-(2-phenylacetamido)-3-cephem-4-carboxylic acid, mp 109° C. (dec.), which was obtained in Example 19.

1. filtrationfollowed by filtration of the reaction mixture
2. washafter which the filtered zinc was washed with a small amount of dimethylformamide
3. additionthe combined solution was poured into a mixture of ethyl acetate (30 ml), water (30 ml) and 10% hydrochloric acid (2 ml)
4. customafter which the ethyl acetate layer was separated
5. extractionThe aqueous layer was further extracted with ethyl acetate (10 ml)
6. washwashed with water
7. dry with materiala saturated sodium chloride aqueous solution, dried over magnesium sulfate
8. distillationafter which the solvent was distilled off
9. customThe residue was crystallized
10. additionby adding a small quantity of acetonitrile
11. filtrationthe precipitated crystals were collected by filtration
12. customdried