摘要:
A series of specific alpha -ketoheterocycles (benzoxazole, thiazole, imidazole, tetrazole, and thiazole-4-carboxylate) has been synthesized in order to assess their potential as beta -lactamase inhibitors. The syntheses were achieved either by construction of the heterocycle (benzoxazole) from an appropriate alpha -hydroxyimidate, followed by oxidation of the alcohol, or by direct reaction of methyl phenaceturate with a lithiated heterocycle. The properties of these compounds in aqueous solution are described and their inhibitory activity against beta -lactamases assessed. They did inhibit the class C beta -lactamase of Enterobacter cloacae P99 but not the TEM beta -lactamase. The most effective inhibitor of the former enzyme (K-i = 0.11 mM) was 5-(phenylacetylglycyl) tetrazole, probably because it is an anion at neutral pH, Interpretation of the results was aided by computational models of the tetrahedral adducts. Most of the compounds also inhibited a-chymotrypsin but not porcine pancreatic elastase. (C) 2001 Elsevier Science Ltd. All rights reserved.