Aminocitrate (and homolog) derivatives have been prepared by bis-alkylation of glycinate Schiff bases with bromoacetates (and ethyl acrylate), followed by N-acylation and esters (partial or complete) deprotection. Aminoisocitrate was similarly obtained by mono-alkylation with diethyl fumarate. Evaluation against representative β-lactamases revealed that the free acid derivatives are modest inhibitors
The complexation of calcium and zinc cations by pyrroglutamate analogs has been studied in the gas phase by means of electrospray ionization mass spectrometry (ESI-MS). Complexes were obtained from the solutions of calcium perchlorate and zinc perchlorate in acetonitrile. The complexes with calcium are singly and doubly charged with various stoichiometries while zinc complexes are singly charged except for one ligand. Solvation with acetonitrile and presence of perchlorate counter-ions are observed when the complexes are in the gas phase. The complexes formed with both metals are mainly L2M and LM species. All tested compounds are better complexing agents for calcium than for zinc.