β-Lactam Derivatives as Enzyme Inhibitors: Carboxy Peptidyl Derivatives of (S)-4-Oxoazetidine-2-carboxylate as Peptidomimetics

4‐Oxoazetidine‐2‐carboxylic acid, protected at the nitrogen by silyl groups, was coupled with amino acid and oligopeptide esters. Desilylation and deprotection of the amino acid residues yielded the free β‐lactam peptides. Structure and properties were elucidated by spectroscopic methods and discussed. Some selected compounds were tested as fibrinogen inhibitors and for thrombocyte aggregation. None of the compounds showed any activity up to a concentration of 10—5 Mol/l. Some other compounds exhibited a weak inhibitory activity against elastase (PPE).