Isolation and structure elucidation of the major degradation products of cefaclor formed under aqueous acidic conditions

J Pharm Sci. 1997 May;86(5):526-39. doi: 10.1021/js960427x.

Abstract

The aqueous acidic degradation of the oral cephalosporin cefaclor was investigated. A number of degradation products were isolated and characterized. The degradation products can be loosely classified into three categories: thiazole derivatives, pyrazine derivatives, and simple hydrolysis or rearrangement products. Degradation pathways are proposed that involve (1) hydrolysis of the beta-lactam carbonyl with subsequent rearrangement, (2) ring contraction of the six-membered cephem nucleus to five-membered thiazole derivatives through an episulfonium ion intermediate, and (3) attack of the primary amine of the phenylglycyl side chain on the "masked aldehyde" at carbon-6 to form fluorescent substituted pyrazines.

MeSH terms

  • Cefaclor / chemistry*
  • Cephalosporins / chemistry*
  • Chromatography, High Pressure Liquid
  • Fluorescence
  • Hydrogen-Ion Concentration
  • Molecular Structure
  • Spectrum Analysis
  • Thiazoles / chemistry
  • Water / chemistry

Substances

  • Cephalosporins
  • Thiazoles
  • Water
  • Cefaclor