To obtain the subject reaction reagent from which a cephalosporin- based antibiotic is synthesized with a simple operation in high yield by essential including a cephalosporin derivative capable of being easily obtained.
This reaction reagent consists essentially of a cephalosporin derivative of formula I (R is a lower alkyl; R1 is H or methoxy). The derivative of formula I is obtained by suspending 7-aminosepham(3)-4-carboxylic acid (preferably 7-aminocephalosporanic acid) of formula H (R2 is methyl or amino) in an inert solvent under a reaction condition, heating and refluxing the obtained suspension in the presence of an excess amount of a sililating agent to provide a compound of formula III, and substituting the compound of formula III with a iodizing reagent. Further, without isolating the derivative, a cephalosporin- based antibiotic can be obtained by subjecting the derivative to a nucleophilic substitution reaction at 3-position of the derivative to provide 3-substituted-7- aminocepham(3)-4-carboxylic acid, and carrying out an acylating reaction or the like of the 3 substituted-7-aminocepham(3)-4-carboxylic acid.
THALER HEINRICH (AT)
LUDESCHER JOHANNES (AT)
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