The Degradation Mechanism of an Oral Cephalosporin: Cefaclor
- 25 October 1996
- journal article
- research article
- Published by Wiley in Helvetica Chimica Acta
- Vol. 79 (7) , 1793-1802
- https://doi.org/10.1002/hlca.19960790705
Abstract
The degradation of cefaclor (1), an oral cephalosporin antibiotic, was studied at 37° in a neutral aqueous medium by HPLC and 1H‐NMR. Under these conditions, 1 underwent intramolecular aminolysis by the 7‐side‐chain NH2 group on the β‐lactam moiety to give a piperazine‐2,5‐dione. The most prominent peak in the HPLC profile of a degradation solution from 1 was isolated by prep. HPLC. Mechanistically, the formation of this degradation product cis‐11 from 1 involves the contraction from a six‐membered cephem ring to a five‐membered ring, which presumably takes place via a common episulfonium ion intermediate 9 (see Scheme). Loss of the Cl‐atom from 3‐chloro‐3‐cephem is a general reaction subsequent to β‐lactam ring opening.Keywords
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