Aminophosphonic Acids and Aminobis(phosphonic acids) as Potential Inhibitors of Penicillin-Binding Proteins

Abstract
Aminophosphonic acids and aminobis(phosphonic acids) have been prepared by the alkylation of Schiff bases with methyl bromoacetate or ethyl acrylate. Other pathways, like the modified Pudovik reaction and Kabachnik-Fields reaction, have been considered for the synthesis of the -phosphonic bioisoster of aminocitrate. Partial or complete deprotection of the phosphonate ester have been realised by either acidic hydrolysis or by treatment with trimethylsilyl bromide. Evaluation against penicillin-binding proteins has shown that our compounds are modest inhibitors of class A -lactamases, but have an interesting activity against R39 (D,D-peptidase/carboxypeptidase).