反应详情

To a solution of acetyl chloride (8 ml.) in methylene chloride (8 ml.) was added 3-acetoxymethyl-7β-(2-hydroxyimino-2-phenylacetamido)-ceph-3-em-4-carboxylic acid (syn-isomer) (500 mg.) in portions over ten minutes with vigorous stirring at room temperature. A gem formed, and ethyl acetate (8 ml.) was added to achieve solution. After stirring for two hours at room temperature, the mixture was added slowly to petroleum spirit (300 ml.) with vigorous stirring. The precipitate was filtered off, washed thoroughly with petroleum spirit, dissolved in chloroform (10 ml.) stirred with activated charcoal and filtered. The filtrate was added dropwise to petroleum spirit (250 ml.) with stirring. The precipitate was filtered off and dried giving the title acid, (350 mg; 62%), τ (DMSO-d6) values include -0.11 (doublet, J 8 Hz; NH), 2.2-2.6 (multiplet; aromatic protons), 7.76 (singlet; CH3. CO2N=), 7.94 (singlet; Ch3C0). Signals at τ 0.05 (doublet, J 9 Hz; NH) and 7.78 (singlet; CH3CO2 =) indicated the presence of about 30% of the anti-isomer.

1. customA gem formed
2. stirringAfter stirring for two hours at room temperature
3. filtrationThe precipitate was filtered off
4. washwashed thoroughly with petroleum spirit
5. dissolutiondissolved in chloroform (10 ml.)
6. stirringstirred with activated charcoal
7. filtrationfiltered
8. additionThe filtrate was added dropwise to petroleum spirit (250 ml.)
9. stirringwith stirring
10. filtrationThe precipitate was filtered off
11. customdried