Phosphorus oxychloride → Chloro-N,N-dimethylformiminium chloride

Participants

Reaction Conditions

Reaction Steps

The Vilsmeier reagent was prepared from dry dimethylformamide (0.26 ml), phosphorus oxychloride (0.31 ml) and dry ethyl acetate (1 ml) according to a conventional method. Dry methylene chloride (40 ml) and 2-trityloxyimino-2-(2-tritylamino-1,3-thiazol-4-yl)acetic acid (syn isomer) (2.1 g) were added thereto at -3° C., and the resulting mixture was stirred for 30 minuts at the same temperature. The resulting solution was added at -10° C. to a suspension, which was prepared by stirring and warming at 40° C. a mixture of 7-amino-3-(1-carboxymethyl-1H-tetrazol-5-yl)thiomethyl-3-cephem-4-carboxylic acid (1.0 g), dry ethyl acetate (40 ml), trimethylsilylacetamide (2.9 g) and bis(trimethylsilyl)acetamide (1.7 g), and the resulting mixture was stirred for 2 hours at -10° to -5° C. Water (30 ml) was added to the reaction mixture and the mixture was filtered. To the filtrate was added methylene chloride (20 ml) and the organic layer was separated. To the organic layer was added water (30 ml) and the mixture was adjusted to pH 7.0 with sodium bicarbonate. The aqueous layer was separated, washed with ethyl acetate and, after addition of ethyl acetate (100 ml), adjusted to pH 3.0 under stirring with conc. hydrochloric acid. The ethyl acetate layer was separated, washed with water, dried over magnesium sulfate and concentrated to dryness to give 7-[2-trityloxyimino-2-(2-tritylamino-1,3-thiazol-4-yl)acetamido]-3-(1-carboxymethyl-1H-tetrazol-5-yl)thiomethyl-3-cephem-4-carboxylic acid (syn isomer) (0.48 g).

Provenance & Evidence