N,N-Dimethylaniline → 7-Aminocephalosporanic acid

Participants

Reaction Conditions

Reaction Steps

3.07 g of the sodium salt of toluene-p-sulphonamide of cephalosporin C having a titre of 83.8% were suspended in 30 ml of methylene chloride. 1.4 ml of triethylamine and 1.9 ml of N,N-dimethylaniline were then added and then 2.4 ml of dimethyldichlorosilane were added over 5 minutes with stirring. Stirring was maintained for 1 hour at 28° C. The solution was then cooled to a temperature of -60° C., after which a solution of 3.13 g of PCl5 in 30 ml of methylene chloride was slowly added, followed by 2.5 ml of N,N-dimethylaniline. After 2 hours of agitation at -40° C. the temperature was reduced again to -60° C. and 0.34 of N,N-dimethylaniline in 9 ml of methanol were added. After two hours at -40° C., 10 ml of water at 90° C. were added and agitation was continued for 5 minutes at 4° C. The aqueous phase was then recovered and the organic phase was extracted with 10 ml of cool water. The combined aqueous extracts were washed with 10 ml of methylene chloride and the pH was adjusted to 3.6-3.7 by addition of concentrated aqueous ammonia solution, with stirring. After allowing the mixture to rest overnight at a low temperature, the precipitate which formed was filtered, washed with methylene chloride, water, acetone and ether, to give 0.80 g (65%) of 7-aminocephalosporanic acid with a spectrophotometric titre of 94.4%.

Provenance & Evidence