Hydrochloric Acid → Chloro-N,N-dimethylformiminium chloride

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Reaction Steps

Vilsmeier reagent was prepared from N,N-dimethylformamide (0.4 g) and phosphoryl chloride (0.8 g) in a conventional manner. 2-Ethoxyimino-2-(2formamidothiazol-4-yl)acetic acid (syn isomer) (1.1 g) was added to the stirred suspension of Vilsmeier reagent in dry tetrahydrofuran (15 ml) under ice cooling and stirred for 30 minutes at same temperature [Solution A]. Trimethylsilylacetamide (4.5 g) was added to the stirred suspension of 7-amino-3-[1-(2-propynyl)-1H-tetrazol-5-yl]thiomethyl-3-cephem-4-carboxylic acid (1.5 g) in dry ethyl acetate (30 ml). To the solution obtained was dropwise added the Solution A at -10° C. and the resulting solution was stirred at same temperature for 0.5 hours. Water (40 ml) was added to the resulting solution, and the separated organic layer was added to water, and the mixture was adjusted to pH 7.5 with a saturated aqueous solution of sodium bicarbonate. The separated aqueous layer was adjusted to pH 2.0 with 10% hydrochloric acid and extracted with ethyl acetate. The extract was washed with a saturated aqueous solution of sodium chloride, dried over magnesium sulfate and then evaporated to give 7-[2-ethoxyimino-2-(2-formamidothiazol-4-yl)acetamido]-3-[1-(2-propynyl)-1H-tetrazol-5-yl]thiomethyl-3-cephem-4-carboxylic acid (syn isomer) (1.72 g).

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