Phosphorus oxychloride → 7-[2-(2-Aminothiazol-4-yl)-2-allyloxyiminoacetamido]-3-cephem-4-carboxylic acid

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Reaction Steps

Phosphoryl chloride (0.84 g.) was added dropwise to a stirred suspension of 2-(2-aminothiazol-4-yl)-2-allyloxyiminoacetic acid (syn isomer, 1.0 g.), tetrahydrofuran (10 ml.) and water (0.05 ml.) at 5° C., and stirred at the same temperature for 20 minutes. Trimethylsilylacetamide (0.66 g.), phosphoryl chloride (0.84 g.) and N,N-dimethylformamide (0.45 g.) were added to a solution, and stirred at 5° C. for an hour to prepare the activated acid solution. On the other hand, trimethylsilylacetamide (4.0 g.) was added to a suspension of 7-amino-3-cephem-4-carboxylic acid (0.88 g.) in tetrahydrofuran (10 ml.) at 40° C., and stirred for 30 minutes. To the solution was added all at once the activated acid solution obtained above at -20` C., and stirred at 0° C. for an hour. After water (20 ml.) was added to the resultant solution at -20° C., the solution was adjusted to pH 7.5 with an aqueous solution of sodium bicarbonate. Ethyl acetate was added to the solution, and the aqueous layer was separated. The solution was washed with ethyl acetate and diisopropyl ether in turn, adjusted to pH 5.0 and treated with activated charcoal. After the solution was adjusted to pH 3.0, the precipitates were collected by filtration, washed with water and dried over phosphorus pentoxide to give 7-[2-(2-aminothiazol-4-yl)-2-allyloxyiminoacetamido]-3-cephem-4-carboxylic acid (syn isomer, 0.8 g.).

Provenance & Evidence