Phosphorus oxychloride → Chloro-N,N-dimethylformiminium chloride

Participants

Reaction Steps

The solution of Vilsmeier reagent was prepared from dry N,N-dimethylformamido (0.475 g) and phosphoryl chloride (0.997 g) in dry tetrahydrofuran (1 ml) in a usual manner. A solution of 2-(2-cyclopenten-1-yl)oxyimino-2-(2-formamidothiazol-4-yl)acetic acid (syn isomer) (1.91 g) in dry tetrahydrofuran (12 ml) was added to the stirred suspension of the solution of Vilsmeier reagent at 0° to 5° C. and the mixture was stirred for 20 minutes. The resulting mixture was added to a solution of 7-amino-3-(4-carboxypyridin-2-yl)thiomethyl-3-cephem-4-carboxylic acid (1.84 g) and sodium bicarbonate (0.84 g) in a mixture of acetone (12 ml) and water (12 ml) at -3° to 0° C. and the mixture was stirred at the same temperature for 40 minutes. The reaction mixture was evaporated under reduced pressure. The residue was adjusted to pH 6.5 with 10% hydrochloric acid, washed with ethyl acetate, concentrated to a small volume and then adjusted to pH 2.9 with 10% hydrochloric acid. The precipitates were collected by filtration, washed with water and dried over phosphorus pentoxide to give 7-[2-(2-cyclopenten-1-yl)oxyimino-2-(2-formamidothiazol-4-yl)acetamido]-3-(4-carboxypyridin-2-yl)thiomethyl-3-cephem-4-carboxylic acid (syn isomer) (2.74 g).

Provenance & Evidence