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Abstract Synthetic chiral platforms can be a powerful platform for enantioselective interactions, especially when coupled with redox‐mediated electrochemical processes. While metallopolymers are versatile platforms for molecularly selective binding, their application for chiral applications is limited. In particular, the recognition and separation of biologically relevant chiral molecules can be key for biomanufacturing and diagnostics. Here, the design of chiral redox‐polymers enables electrochemically‐controlled enantioselective interactions, and supramolecular chirality is leveraged for enhancing recognition towards target enantiomers. Chiral redox‐metallopolymers are synthesized based on Ugi's amine‐inspired chiral monomers, and their enantioselective recognition toward ionic enantiomers such as tryptophan and naproxen is demonstrated, with higher enanhcement provided by the chiral redox‐polymer over the single‐site, chiral building bloack itelf. 2D nuclear magnetic resonance spectroscopy and solid‐state circular dichroism support the emergence of supramolecular chirality resulting from the intramolecular interaction between the ferrocene and the alkyl group in the backbone. The half potential shift of the redox‐polymers behaves linearly from 0% to 100%eel‐tryptophan to enable enantiomer quantification. Investigation on solvent polarity and pH effect reveal that the enantioselective mechanism is attributed to the subtle balance between hydrogen bonding and π–π interaction. This study highlights the potential of chiral redox‐metallopolymers as platforms for electrochemically‐modulated enantioselective interactions towards a range of amino acids and pharmaceutical carboxylates.
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Anion-binding catalyst designs for enantioselective synthesis
Select hydrogen bond donors can catalyze reactions of ion pairs through the recognition of anions. This mode of action can be exploited in enantioselective catalysis if a suitable chiral hydrogen bond donor is applied. Beyond just anionic recognition, an enantioselective anion-binding catalyst often must host numerous non-covalent interactions, including hydrogen bonding, general base, π-π, and π-cation, to achieve high levels of enantiocontrol. Anion-binding catalysts can be strategically designed to support those non-covalent interactions required to render a process highly stereoselective. Tactics applied in anion-binding catalyst development include enhancing arene substituents for improved π-stacking, linking two anion-binding units together on a single scaffold, expanding types of functional groups for anion recognition, and building frameworks with bifunctional modes of action. The intent of this digest is to highlight observations that suggest as anion-binding catalyst designs advance, their associated synthetic methodologies for complex molecule construction become increasingly impressive.
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- Award ID(s):
- 1362030
- PAR ID:
- 10054917
- Date Published:
- Journal Name:
- Tetrahedron letters
- Volume:
- 58
- Issue:
- 27
- ISSN:
- 0040-4039
- Page Range / eLocation ID:
- 2623-2628
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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