| 摘要 |
NEW MATERIAL:The compound of formula [X is S, O, SO or SO2; R1 is H or lower alkoxy; R2 is H, (substituted) acyl or (substituted) silyl; R3 is (substituted) carboxyl or carboxyl saltl; R4 is H, halogen, hydroxymethyl, lower alkyl etc.]. EXAMPLE:7beta-Amino-7alpha-methoxy-3-(1H-tetrazol-5-yl)thiomethyl-3-ce phem-4-carbo xylic acid benzhydryl ester. USE:A synthetic intermediate for producing a cephalosporin antibiotic substance such as cefaclor in high yield and purity. PREPARATION:Bis(trimethylsilyl)trifluoroacetamide is added to 7-amino- cephalosporanic acid and themixture is made to react with 4-pyridylthioacetic acid chloride hydrochloride. The pH of the reaction system is adjusted with triethylamine to crystallize the objective compound. |
