Formation of a tris(catecholato) iron(iii) complex with a nature-inspired cyclic peptoid ligand

Abstract

Siderophore-mimicking macrocyclic peptoids were synthesized. Peptoid 3 with intramolecular hydrogen bonds showed an optimally arranged primary coordination sphere leading to a stable catecholate-iron complex. The tris(catecholato) structure of 3-Fe(III) was...

Advances in the Synthesis of Enterobactin, Artificial Analogues, and Enterobactin-Derived Antimicrobial Drug Conjugates and Imaging Tools for Infection Diagnosis

“…In 2021, Seo and co-workers described the synthesis of the triscatecholate enterobactin mimics 277 and 278 (Scheme 19) based on a ferrichrome-type cyclic hexapeptidic backbone. 239 Following the same synthesis approach as D'Amato and co-workers, 238 they assembled the linear alternating N-alkylated glycine hexamers 273 and 274 on 2-Cl-Trt resin via a sequence of coupling of 2-bromoacetic acid (266) to a growing chain and subsequent nucleophilic substitution of the bromine with the primary amines 265a and 271 bearing different catecholate units.…”

“…Scheme19 Triscatecholate enterobactin mimic based on a ferrichrome-type cyclic hexapeptidic backbone by Seo and co-workers 239. …”

Structure – Bioactivity Relationship in Cyclic Peptoids: An Overview

“…The increasing interest in the control of iron(III) concentration in the human body led to the design of novel molecular architectures capable to remove ferrous and ferric ions, which produce reactive oxygen species under aerobic conditions. Inspired by natural occurring enterobactin and related species, both De Riccardis [48] and Seo [49] groups recently proposed cyclotrimeric‐ and hexameric peptoids decorated with catechol pending moieties. Similar convergent syntheses exploited protected catechol‐containing submonomers, subsequently deprotected after the cyclization step to afford the final products (yield over two steps, cyclization and side‐chains deprotection: 6 , 24 %; 7 , not reported).…”

“…The increase of the ring size resulted in an overall decrease of the binding affinity. The nature of the catechol unit, incorporated as dopamine or as an amido(catechol) group ( 7 ‐Fe(III), Figure 7), influences both stoichiometry (1 : 1 rather than 2 : 1) and the affinity towards ferric ion, as demonstrated by spectrophotometric titrations [49] …”

Hydroxypyridinone-Based Metal Chelators towards Ecotoxicity: Remediation and Biological Mechanisms

“…A cyclic hexapeptoid scaffold inspired by ferrichrome A and containing a tris-(catecholate)-binding system, was also quite recently used in the design of hexadentate compounds in order to associate good iron chelation with resistance to degradation by hydrolytic enzymes. It was found that the introduction of amide groups next to catechol moieties in R 1 substituents, as well as the orientation of the two hydroxyl groups towards the center of the macrocycle, was important in the stabilization of the Fe 3+ - L20 complex, through the establishment of intramolecular hydrogen bonds between amide protons and catechol oxygen atoms [ 59 ]. L20 is able to form an iron complex more stable than Fe 3+ -DFO, but the lability of the peptoid skeleton and the low solubility in aqueous media, prevents eventual environment applications.…”