Process for preparing cephalosporins
AssigneeLilly Industries Limited
InventorsMichael Davison, David Binfield Frankham, Thomas William Matches Spence
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Abstract
An improved process for preparing antibacterially active 7-.alpha.-aminoacetamido cephalosporin-4-carboxylic acids in which a 7-aminocephalosporin-4-carboxylic acid ester is reacted with an activated form of an .alpha.-aminoacetic acid, the amino group of which is protected by a .beta.-dicarbonyl group, this amino group being removed after the acylation in the presence of a sufficient amount of a hydrazine derivative to prevent re-reaction of the .beta.-dicarbonyl protecting agent with the cephalosporin.
Claims5
In a process for preparing a 7-.alpha.-aminoacetamido cephalosporin in which (a) a 7-aminocephalosporin-4-carboxylic acid ester is reacted with an activated form of an .alpha.-aminoacetic acid, the amino group of which is protected by reaction with a .beta.-dicarbonyl compound of the formula ##EQU5## in which R.sup.7 is C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy, to form an enamine;
- and (b) the amino protecting group is removed from the resulting protected 7-.alpha.-aminoacetamido cephalosporin compound;
- the step which comprises adding to the reaction mixture from step (b) an amount of a hydrazine or a semicarbazide sufficient to prevent re-reaction of the .beta.-dicarbonyl compound with the produced 7-.alpha.-aminoacetamido cephalosporin.
Dependencies are inferred from the claim text.