反应详情

A mixture of 0.178 g. of 7-acetoacetamido-3-acetoxymethyl-3-cephem-4-carboxylic acid, 0.42 g. of sodium hydrogen carbonate, 0.64 g. of 5-methyl-1,3,4-oxadiazole-2-thiol and 10 ml. of a phosphate buffer of pH 6.4 is heated at 55°-60° C for 16 hours. After cooling, the reaction mixture is shaken with ethyl acetate and the water layer is taken, adjusted to pH 2 with 50 % phosphoric acid and extracted three times with ethyl acetate. The extracts are pooled, washed with water and dehydrated over sodium sulfate. Then, the solvent is distilled off and ether is added to the residue, whereupon 0.10 g. (48 %) of 7-acetoacetamido-3-(5-methyl-1,3,4-oxadiazol-2-yl)thiomethyl-3-cephem-4-carboxylic acid is obtained as crystals melting at 80°-85° C(decomp.).

1. additionA mixture of 0.178 g
2. temperatureAfter cooling
3. extractionextracted three times with ethyl acetate
4. washwashed with water
5. distillationThen, the solvent is distilled off
6. additionether is added to the residue, whereupon 0.10 g