Intramolecular general acid catalysis in the aminolysis of β-lactam antibiotics

Antonio Llinás, Michael I. Page

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


The rate of aminolysis of benzylpenicillin and cephaloridine by hydroxylamine, unlike other amines, shows only a first order dependence on amine concentration. The rate enhancement compared with that predicted from a Bronsted plot for other primary amines with benzylpenicillin is greater than 106. This is much more than an α-effect and is compatible with rate-limiting formation of the tetrahedral intermediate due to a rapid intramolecular general acid catalysed breakdown of the intermediate. For cephaloridine, the rate enhancement is greater than 104 which demonstrates that β-lactam C-N bond fission and expulsion of the leaving group at C3′ are not concerted.

Original languageEnglish
Pages (from-to)651-654
Number of pages4
JournalOrganic and Biomolecular Chemistry
Issue number5
Early online date9 Feb 2004
Publication statusPublished - 7 Mar 2004


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