Bio-inspired Herringbone Foldamers: Strategy for Changing the Structure of Helices

Adam, Abdulselam; Haberhauer, Gebhard; Wölper, Christoph

doi:10.1021/acs.joc.7b00185

Cited by 6 publications

(5 citation statements)

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“…This is an already described effect whereby the extent of the bending increases with increasing size of the substituents attached to the α-carbon atoms. [34] In all studied N-aryl imidazole platforms the dihedral angles between the aryl rings and the imidazole rings deviate only slightly from 90°. As a result, the bromine substituents in platforms m-23 and o-23 are oriented almost perpendicular to the plane formed by the three imidazole rings.…”

Section: C) Structural Investigations In Solid State and Gas Phase Camentioning

confidence: 92%

N‐Aryl Imidazole Platforms – Synthesis and Structural Investigation

et al. 2018

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Cyclic oligomers of azole peptides were isolated from a multitude of marine organisms and were used for a variety of applications in supramolecular chemistry. Up to now the use of imidazole‐containing platforms based on Lissoclinum cyclopeptides were limited to N‐alkyl imidazole scaffolds. Here we present the synthesis of chiral N‐aryl imidazole amino acids by starting from the corresponding amidoketones and aniline derivatives. By using the optimized reaction conditions even chiral imidazoles with large substituents at the α‐carbon atom and at ortho position of the aryl ring were obtained without racemization at the stereogenic center. Subsequent one‐pot cyclotrimerization of the N‐aryl imidazole amino acids leads to the desired C3‐symmetric platforms in rather good yields. The investigation of the structures of the platforms with bromine atoms in ortho, meta and para position relative to the imidazole unit were conducted by NMR spectroscopy, X‐ray crystallography, and quantum chemical calculations. The experimental data reveals that the ortho isomer is present in a single conformer in which all bromine atoms are oriented in the same direction. The rotation around the aryl‐imidazole axis in this isomer is completely prevented in the measured temperature range.

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Section: C) Structural Investigations In Solid State and Gas Phase Camentioning

confidence: 92%

N‐Aryl Imidazole Platforms – Synthesis and Structural Investigation

et al. 2018

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“…Satisfyingly 490 can be obtained following simpler protocols in milder conditions (Scheme B). Recent works report the synthesis of 490 in two steps, starting with heating 397 in the presence of K 2 CO 3 or NaH and acetamide. The intermediate 480 was identified and resulted from the aromatic nucleophilic substitution of Cl by acetamide, assisted by the base.…”

Section: Divergent Synthesis Pathwaysmentioning

confidence: 99%

“…462 The best optimized conditions (Pd(OAc) 2 , dppf, highly polar DMF and K 2 CO 3 ) afforded several phosphine bearing phen (2,9)sub (477-482, Scheme 81B). Interestingly, it is possible to avoid the use of costly palladium catalysts as demonstrated by Wei and Liu et al using 406 and HP(O)Ph 2 (471) in the presence of NiCl 2 (dppp) to reach 483 in a very satisfactory yield (Scheme 81C). 463 Reactivity of Halogenated phen (2,9)sub and phen (2)sub : Nucleophilic Substitutions.…”

Section: Synthesis and Exploitation Of The Reactivity Of Phenanthroli...mentioning

confidence: 99%

“…Satisfyingly 490 can be obtained following simpler protocols in milder conditions (Scheme 82B). Recent works report the synthesis of 490 in two steps, starting with heating 397 in the presence of K 2 CO 3 471 or NaH 93 397 by sodium azide yields 493, which is then reduced into 490 by NaBH 4 (Scheme 82C). 472 The overall yield (51%) is, however, lower than that with the above strategies.…”

Section: Synthesis and Exploitation Of The Reactivity Of Phenanthroli...mentioning

confidence: 99%

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Fifty Shades of Phenanthroline: Synthesis Strategies to Functionalize 1,10-Phenanthroline in All Positions

Queffélec,

Pati,

Pellegrin

2024

Chem. Rev.

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1,10-Phenanthroline (phen) is one of the most popular ligands ever used in coordination chemistry due to its strong affinity for a wide range of metals with various oxidation states. Its polyaromatic structure provides robustness and rigidity, leading to intriguing features in numerous fields (luminescent coordination scaffolds, catalysis, supramolecular chemistry, sensors, theranostics, etc.). Importantly, phen offers eight distinct positions for functional groups to be attached, showcasing remarkable versatility for such a simple ligand. As a result, phen has become a landmark molecule for coordination chemists, serving as a must-use ligand and a versatile platform for designing polyfunctional arrays. The extensive use of substituted phenanthroline ligands with different metal ions has resulted in a diverse array of complexes tailored for numerous applications. For instance, these complexes have been utilized as sensitizers in dye-sensitized solar cells, as luminescent probes modified with antibodies for biomaterials, and in the creation of elegant supramolecular architectures like rotaxanes and catenanes, exemplified by Sauvage’s Nobel Prize-winning work in 2016. In summary, phen has found applications in almost every facet of chemistry. An intriguing aspect of phen is the specific reactivity of each pair of carbon atoms ([2,9], [3,8], [4,7], and [5,6]), enabling the functionalization of each pair with different groups and leading to polyfunctional arrays. Furthermore, it is possible to differentiate each position in these pairs, resulting in non-symmetrical systems with tremendous versatility. In this Review, the authors aim to compile and categorize existing synthetic strategies for the stepwise polyfunctionalization of phen in various positions. This comprehensive toolbox will aid coordination chemists in designing virtually any polyfunctional ligand. The survey will encompass seminal work from the 1950s to the present day. The scope of the Review will be limited to 1,10-phenanthroline, excluding ligands with more intracyclic heteroatoms or fused aromatic cycles. Overall, the primary goal of this Review is to highlight both old and recent synthetic strategies that find applicability in the mentioned applications. By doing so, the authors hope to establish a first reference for phenanthroline synthesis, covering all possible positions on the backbone, and hope to inspire all concerned chemists to devise new strategies that have not yet been explored.

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“…Recently, Haberhauer et al. showed a significant conversion from a canonical helix [14a] into a noncanonical helix with a herringbone form [14b] by introduction of a single methyl group to an aliphatic carbon in the imidazole containing δ ‐amino acid oligomers. Here we reported a new type of herringbone helical foldamers solely based on aromatic backbones, in which relatively flexible diaryl ether structural motifs were fused into an ϵ ‐amino acid to serve as turn motifs for herringbone formation.…”

Section: Introductionmentioning

confidence: 99%

Herringbone Helical Foldamers from Aromatic Ether Derived ϵ‐Amino Acid Peptides

Yang,

Xue

2023

Chemistry A European J

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Oligomers based on an aromatic ether derived ϵ‐amino acid peptides folded into herringbone helical structures, induced by successive NH−O−NH & O−NH−O bifurcated hydrogen bonding interactions and reinforced by π‐π stacking between aryls from adjacent layers. The diaryl ether bonds −O− worked both as structural units to provide turn motifs for changing the amplitude of the slope along the axis of helix for herringbone formation, and also as acceptors for hydrogen bonding. Attachment of a single chiral carbon to the C‐termini of the peptides induced excess of single‐handed screw sense and amplification through the chain propagation as exemplified by chain length dependent circular dichroism (CD) investigations.

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Bio-inspired Herringbone Foldamers: Strategy for Changing the Structure of Helices

Cited by 6 publications

References 61 publications

N‐Aryl Imidazole Platforms – Synthesis and Structural Investigation

N‐Aryl Imidazole Platforms – Synthesis and Structural Investigation

Fifty Shades of Phenanthroline: Synthesis Strategies to Functionalize 1,10-Phenanthroline in All Positions

Herringbone Helical Foldamers from Aromatic Ether Derived ϵ‐Amino Acid Peptides

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