7-Aminocephalosporanic acid → 3-[(2-Methyl-1,3,4-thiadiazol-5-yl-thio)methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid

Participants

Reaction Steps

α-Carboxy-p-chloromethylphenylacetylnitrophenyl polymer, prepared according to the procedure described in Canadian Pat. No. 892,580, carrying 4m. mole of p-chloromethylphenylmalonic acid is suspended for about 8 hours in 20 ml of dry methylene chloride solution containing 1 m. mole of 3-[(2-methyl-1,3,4-thiadiazol-5-ylthio)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid triethylammonium salt, which is prepared from the 7-aminocephalosporanic acid derivative and triethylamineat room temperature. After only traces of 3-[(2-methyl-1,3,4-thiadiazol-5-ylthio)methyl]-7-amino-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid remain in solution, which is determined by thin layer chromatography on cellulose in 70% aqueous propanol, the polymer is filtered off and washed with three portions of 50ml each of methylene chloride. The combined filtrates are evaporated and the residue is dissolved in 20 ml of distilled water. This solution is acidified to pH 2 by adding 0.2 N hydrochloric acid and extracted twice with ethylacetate. The organic solution is dried over sodium sulfate and evaporated to room temperature. The remaining solid is dried overnight over phosphorus pentoxide under vacuum to give 7-[[2-[4-chloromethyl)phenyl]-2-carboxyacetyl]amino]-3-[(2-methyl-1,3,4-thiadiazol-5-yl-thio)methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid.

Provenance & Evidence