反应详情

To an ice-cooled mixture of 7-ADCA (10.0 g, 0.4667 mol), ethanol (270 ml), water (83 ml) and hydrobromic acid (48%, 56.7 ml), sodium nitrite (4.67 g, 0.6769 mol) was added in small portions over 25 minutes and the mixture was stirred for 2.5 hours at ice-temperature. Ethanol was removed under reduced pressure and the residual mass was diluted with methylene chloride, washed with water. The aqueous washings were saturated with brine and re-extracted with methylene chloride. The combined organic layer was washed with brine, dried over anhydrous sodium sulfate and concentrated to give 9.8 g (75.5%) of 7α-bromo-3-methyl-3-cephem-4-carboxylic acid. This crude acid was directly used for the next step without further purification.

1. additionwas added in small portions over 25 minutes
2. customEthanol was removed under reduced pressure
3. additionthe residual mass was diluted with methylene chloride
4. washwashed with water
5. extractionre-extracted with methylene chloride
6. washThe combined organic layer was washed with brine
7. dry with materialdried over anhydrous sodium sulfate
8. concentrationconcentrated