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

Beteiligte Stoffe

Reaktionsschritte

2-(2-Formamidothiazol-4-yl)-2-propargyloxyiminoacetic acid (syn isomer, 1.27 g.), N,N-dimethylformamide (400 mg.), phosphoryl chloride (850 mg.) and ethyl acetate (11.2 ml.) were treated in a conventional manner to give the activated acid solution. The activated acid solution was added to a solution of 7-amino-3-chloro-3-cephem-4-carboxylic acid hydrochloride (2 g.), trimethylsilylacetamide (6 g.) and bis(trimethylsilyl)acetamide (3 ml.) in ethyl acetate (40 ml.) at -15° C. all at once, and stirred at -5° to -10° C. for 1.5 hours. After adding water (30 ml.) to the resultant solution, the ethyl acetate layer was separated and extracted with a saturated aqueous solution of sodium bicarbonate. Ethyl acetate was added to the aqueous extract, adjusted to pH 2.0 with 10% hydrochloric acid. The ethyl acetate layer was separated, washed with water, dried over magnesium sulfate and filtered. The filtrate was concentrated in vacuo, and the residue was crystallized with a mixture of ethyl acetate and diisopropyl ether. The precipitates were collected by filtration and dried to give 7-[2-(2-formamidothiazol-4-yl)-2-propargyloxyiminoacetamido]-3-chloro-3-cephem-4-carboxylic acid (syn isomer, 1.5 g.), yellow powder.

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