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

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Reaction Steps

Phosphoryl chloride (1.4 g.) was added dropwise to a suspension of 2-(2-aminothiazol-4-yl)-2-propargyloxyiminoacetic acid (syn isomer, 1.7 g.) in tetrahydrofuran (15 ml.) below 7° C., and stirred at the same temperature for 10 minutes. Phosphoryl chloride (1.4 g.), trimethylsilylacetamide (1.3 g.) and N,N-dimethylformamide (0.76 g.) were added to a solution, and stirred for 20 minutes to prepare the activated acids solution. On the other hand, trimethylsilylacetamide (7.8 g.) was added to a suspension of 7-amino-3-cephem-4-carboxylic acid (1.5 g.) in tetrahydrofuran (20 ml.), and stirred at 40° C. for 30 minutes. To the solution was added all at once the activated acid solution obtained above at -20° C., and stirred for 30 minutes at 0° C. After adding water (20 ml.) to the resultant solution at -20° C., the solution was adjusted to pH 7.5 with an aqueous solution of sodium bicarbonate. The aqueous layer was separated, washed with ethyl acetate and diisopropyl ether in turn, and treated with activated charcoal at pH 5.5. The solution was adjusted to pH 3.0, and the precipitates were collected by filtration and dried over phosphorus pentoxide under reduced pressure to give 7-[2-(2-aminothiazol-4-yl)-2-propargyloxyiminoacetamido]-3-cephem-4-carboxylic acid, (syn isomer, 1.47 g.).

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