PREPARATION OF CEPHAMYCIN DERIVATIVE

PURPOSE:To prepare the titled compound useful as an intermediate of antibacterial agent, easily, economically, in an idustrial scale, in high yield, by reacting a specific cephamycin C with a carboxylic acid halide in a halogenated hydrocarbon solvent, thereby carrying out the acyl exchange reaction continuously. CONSTITUTION:The compound of formulaI{R is amino protected with electrophilic group; R is H or halogen; R is hetero-ring group[hetero-ring is (substituted) 1H-tetrazol-5-yl, (substituted) 1,3,4-thiadiazol-2-yl, etc.]}is made to react with the compound of formula R -X (R is acyl; X is halogen) is a halogenated hydrocarbon solvent to obtain the cephamycin derivative of formula II. The solvent is preferably dichloromethane, chloroform, or especially, 1,2-dichloroethane.