Phosphorus oxychloride → Chloro-N,N-dimethylformiminium chloride

Participants

Reaction Steps

Vilsmeier reagent was prepared from phosphorus oxychloride (1.29 g) and dimethylformamido (0.62 g) in ethyl acetate (30 ml) in a usual manner. 2-(2-Formamidothiazol-4-yl)-2-methoxyiminoacetic acid (syn isomer) (1.6 g) was added to the stirred suspension of the Vilsmeier reagent in ethyl acetate (2 ml) and tetrahydrofuran (10 ml) under ice-cooling and stirred at the same temperature for 0.5 hours to produce an activated acid solution. N-(Trimethylsilyl)acetamide (5.0 g) was added to the stirred suspension of benzhydryl 7-amino-3-[2-(2-pyridyl)vinyl]-3-cephem-4-carboxylate (trans isomer) (3 g) in ethyl acetate (30 ml) and stirred at 40° to 43° C. for 30 minutes. To the clear solution was added the activated acid solution prepared above at -20° C. and stirred at the same temperature for 30 minutes. Water (30 ml) was added to the resulting solution, and separated organic layer was washed with 5% aqueous sodium bicarbonate and brine, dried over magnesium sulfate and evaporated to give benzhydryl 7-[2-methoxyimino-2-(2-formamidothiazol-4-yl)acetamido]-3-[2-(2-pyridyl)vinyl]-3-cephem-4-carboxylate (syn isomer) (trans isomer) (4.1 g).

Provenance & Evidence