反应详情

N,N-Dimethylformamido (0.75 g) and phosphoryl chloride (1.57 ml) were mixed to prepare Vilsmeier reagent in a usual manner, and the resultant Vilsmeier reagent was suspended in dry ethyl acetate (22 ml). To the suspension was added 2-(2-formamidothiazol-4-yl)-2-(2-cyclopenten-1-yloxyimino) acetic acid (A isomer) (syn isomer) (2.3 g) under ice-cooling with stirring, and then the mixture was stirred for an hour to prepare an activated acid solution. To a solution of bis(trifluoroacetic acid )salts of 7β-amino-3-(2-methyl-1-pyrazolio)methyl-3-cephem-4-carboxylate (4.7 g) and N-mono(trimethylsilyl)acetamido (11.8 g) in ethyl acetate (50 ml) was added the activated acid solution prepared above at 3° C. After stirring at the same temperature for an hour, the mixture was poured into diisopropyl ether (500 ml). The precipitates were collected by filtration and successively washed with diisopropyl ether to give trifluoroacetic acid salt of 7β-[2-(2-formamidothiazol-4-yl)-2-(2-cyclopenten-1-yloxyimino)acetamido]-3-(2-methyl-1-pyrazolio)methyl- 3-cephem-4-carboxylate (A isomer) (syn isomer) (6.02 g).

1. temperaturecooling
2. stirringthe mixture was stirred for an hour
3. customto prepare an activated acid solution
4. customprepared above at 3° C
5. stirringAfter stirring at the same temperature for an hour
6. filtrationThe precipitates were collected by filtration
7. washsuccessively washed with diisopropyl ether