Phosphorus oxychloride → Chloro-N,N-dimethylformiminium chloride

Participants

Reaction Steps

Vilsmeier reagent was prepared from phosphorus oxychloride (1.1 g) and N,N-dimethylformamide (0.5 g) in ethyl acetate (2.0 ml) in a conventional manner. 2-[2-(2,2,2-Trifluoroacetamido)-5-chlorothiazol-4-yl]-2-propargyloxyiminoacetic acid (syn isomer, 2.2 g) was added to the stirred suspension of Vilsmeier reagent in tetrahydrofuran (22 ml) under ice cooling and stirred for 20 minutes at same temperature [Solution A]. Trimethylsilylacetamide (5.1 g) was added to the stirred suspension of 7-aminocephalosporanic acid (1.5 g) in tetrahydrofuran (30 ml); and the mixture was stirred for 30 minutes at 35° to 40° C. To the solution was added the solution [Solution A] at -10° C., and the resulting solution was stirred at the same temperature for 30 minutes. Water and ethyl acetate were added to the reaction mixture at -10° C. The organic layer was separated and added to water. The mixture was adjusted to pH 7.5 with a saturated aqueous solution of sodium bicarbonate. The aqueous layer was separated and adjusted to pH 2.0 with 10% hydrochloric acid, and then extracted with ethyl acetate. The extract was washed with a saturated aqueous solution of sodium chloride, dried over magnesium sulfate and evaporated under reduced pressure to give 7-[2-(2,2,2-trifluoroacetamido)-5-chlorothiazol-4-yl]-2-propargyloxyiminoacetamido]cephalosporanic acid (syn isomer, 2.51 g).

Provenance & Evidence