反应详情

Vilsmeir reagent prepared from N,N-dimethylformamide (3.76 ml) and phosphorus oxychloride (4.46 ml) was suspended in dry tetrahydrofuran (50 ml). To the suspension was added 4-chloro-2-methoxycarbonylmethoxyimino-3-oxobutyric acid (syn isomer) (10.5 g), and the mixture was stirred under ice-cooling to prepare the activated acid solution. This solution was added at a time to a solution of 7-amino-3-vinyl-3-cephem-4-carboxylic acid (10 g) and trimethylsilylacetamide (35 g) in ethyl acetate (110 ml) at -30° C. After the reaction mixture was stirred at -15° C. for an hour, the resultant solution was poured into water (100 ml) and then extracted with ethyl acetate (200 ml). The extract was washed with a saturated aqueous sodium chloride and dried over magnesium sulfate. The solvent was evaporated under reduced pressure and the residue was triturated with diisopropyl ether to give 7-(4-chloro-2-methoxycarbonylmethoxyimino-3-oxobutyramido)-3-vinyl-3-cephem-4-carboxylic acid (syn isomer) (16.75 g).

1. temperaturecooling
2. customto prepare the activated acid solution
3. stirringAfter the reaction mixture was stirred at -15° C. for an hour
4. extractionextracted with ethyl acetate (200 ml)
5. washThe extract was washed with a saturated aqueous sodium chloride
6. dry with materialdried over magnesium sulfate
7. customThe solvent was evaporated under reduced pressure
8. customthe residue was triturated with diisopropyl ether