Mechanistic insights into Smiles rearrangement. Focus on π–π stacking interactions along the radical cascade

Khartabil, Hassan; Doudet, Ludovic; Allart‐Simon, Ingrid; Ponce-Vargas, Miguel; Gérard, Stéphane; Hénon, Éric

doi:10.1039/d0ob01511c

Cited by 14 publications

(12 citation statements)

References 40 publications

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“…Like many QTAIM 16 -based analytical methods the Δg inter score and IBSI are exempt of issues related to basis set superposition error. Both Δg inter score and IBSI have previously been successfully applied in mechanistic studies for the rationalization of the discrimination between competing reaction pathways 52 and are particularly useful in assessing reactional predispositions in so-called reactant complexes. Like shown below, oxidized cobaltacycles can be considered as typical reactant complexes at a mechanistic crossroad that are capable of either evolving by reductive elimination by the coupling of ligand X with the phpy, which corresponds to observation reported by Perez-Temprano et al 13 for the thiolated complex [Cp*Co(SCF 3 )(phpy)] or by cyclocondensation of phpy with the Cp* ligand (this report).…”

Section: Dft Evaluation Of the Mechanism Of Formation Of [2a] + Nci Plots And Ibsi Suggest A Predisposition To Cyclocondensationmentioning

confidence: 99%

Fate of Cobaltacycles in Cp*Co-Mediated C–H Bond Functionalization Catalysis: Cobaltacycles May Collapse upon Oxidation via Co(IV) Species

Deraedt

Cornaton

et al. 2021

Organometallics

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Recent reports have identified Cp*Co-based complexes as powerful catalysts for aromatic C-H bond activation under oxidative conditions. However, little is known about the speciation of Cp*Co species during catalysis. We now show that key intermediates, Cp*Co(III) metallacycles derived from 2-phenylpyridine (phpy-H), react swiftly in solution with one-electron oxidants to irreversibly collapse by a cyclocondensation of the organic ligands to afford cationic alkaloids in yields of >70 %. Low temperature EPR analysis of a mixture of cobaltacycle with the tritylium cation reveals the signatures of trityl and Co(IV)-centred radicals. Electrochemical analyses show that the oxidation of these cobaltacycles is irreversible and gives rise to several products in various amounts, among which the most salient ones are a cationic alkaloid resulting from the cyclocondensation of the phpy and Cp* ligands, and the dimeric cation {[Cp*Co] 2 (-I) 3 } + . DFT investigations of relevant noncovalent interactions using QTAIMbased NCI plots and Intrinsic Bond Strength Index suggest a ligand-dependent predisposition by "NCI-coding" for the Co(IV)templated cyclocondensation, the computed reaction network energy profile for which supports the key roles of a short lived Co(IV) metallacycle and of a range of triplet state organocobalt intermediates. These data are provided free of charge by the joint Cambridge Crystallographic Data Centre and Fachinformationszentrum Karlsruhe Access Structures service www.ccdc.cam.ac.uk/structures. Full experimental procedures and details, voltammograms, EPR, Mass and NMR spectra, energies and Cartesian coordinates, high resolution NCI figures. This material is available free of charge via the Internet at http://pubs.acs.org.

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Section: Dft Evaluation Of the Mechanism Of Formation Of [2a] + Nci Plots And Ibsi Suggest A Predisposition To Cyclocondensationmentioning

confidence: 99%

Fate of Cobaltacycles in Cp*Co-Mediated C–H Bond Functionalization Catalysis: Cobaltacycles May Collapse upon Oxidation via Co(IV) Species

Deraedt

Cornaton

et al. 2021

Organometallics

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“…Actually, the π‐stacking interaction is a key notion to a large part of chemist's qualitative understanding of NCIs. In intramolecular situation, this interaction is expected to play a relevant role in stabilizing certain conformations, and can even be partly responsible of specific channels within an overall reaction mechanism [38] . From this perspective, prior to any calculation, the two conformers exhibit a clear difference since only the boat conformation can significantly bring the two phenyl rings close to each other.…”

Section: Resultsmentioning

confidence: 99%

“…In intramolecular situation, this interaction is expected to play a relevant role in stabilizing certain conformations, and can even be partly responsible of specific channels within an overall reaction mechanism. [38] From this perspective, prior to any calculation, the two conformers exhibit a clear difference since only the boat conformation can significantly bring the two phenyl rings close to each other. An IGMdg analysis was performed in an attempt to clarify and quantify this point.…”

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confidence: 99%

Deciphering the Role of Noncovalent Interactions in the Conformations of Dibenzo‐1,5‐dichalcogenocines

et al. 2022

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This work reports a combined experimental and theoretical study on the new dibenzo‐1,5‐ditellurocine 2‐Te in order to get an overview on the parameters controlling conformational change and to explain the differences with sulfur and selenium analogues. The preference of the boat conformer over the chair one is revealed by DFT calculations. For 2‐Te, a ΔG value of about 3 kJ/mol was calculated, close to the value measured by NMR (5 kJ/mol). However, DFT calculations with implicit solvation effects could not clearly establish the presence of an intramolecular Te…HC noncovalent interaction (NCI), as observed in the solid state. The Independent Gradient Model (IGM) methodology discloses an existent but probably not sufficiently discriminating Te…HC NCI. It also confirms that van der Waals interactions between phenyl rings is a source of stabilization of the boat conformer. Furthermore, electrostatic potential analysis suggests that chalcogen bonds between Te σ‐holes and solvent might play an important role.

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“…As part of our ongoing program dealing with the synthesis of complex indole-heterocycles by tandem reactions, we previously investigated whether a 5-exo-trig cyclisation could be innovatively combined to a radical promoted Smiles rearrangement [19]. A recent study established and validated a computational tool to develop mechanistic investigations enabling the synthesis of new scaffolds of therapeutic interest by this approach [20]. Because of the interest of indoloquinoline scaffold for drug discovery [21], we studied the preparation of indolo [2,3-b]quinoline derivatives by a domino process including radical Smiles rearrangement [22][23][24].…”

Section: Preparation Of Indoloquinoline Derivativesmentioning

confidence: 99%

Synergy between Indoloquinolines and Ciprofloxacin: An Antibiofilm Strategy against Pseudomonas aeruginosa

et al. 2021

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Antibiotic treatments can participate in the formation of bacterial biofilm in case of under dosage. The interest of indoloquinoline scaffold for drug discovery incited us to study the preparation of new indolo [2,3-b]quinoline derivatives by a domino radical process. We tested the effect of two different “indoloquinoline” molecules (Indol-1 and Indol-2) without antimicrobial activity, in addition to ciprofloxacin, on biofilm formation thanks to crystal violet staining and enumeration of adhered bacteria. This association of ciprofloxacin and Indol-1 or Indol-2 attenuated the formation of biofilm up to almost 80% compared to ciprofloxacin alone, or even prevented the presence of adhered bacteria. In conclusion, these data prove that the association of non-antimicrobial molecules with an antibiotic can be a solution to fight against biofilm and antibiotic resistance emergence.

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Mechanistic insights into Smiles rearrangement. Focus on π–π stacking interactions along the radical cascade

Abstract: The synthesis of new arene and heteroarene scaffolds of therapeutic interest has generated a renewed interest in the domino radical cyclisation–Smiles. In this work we present a detailed mechanistic investigation...

Cited by 14 publications

References 40 publications

Fate of Cobaltacycles in Cp*Co-Mediated C–H Bond Functionalization Catalysis: Cobaltacycles May Collapse upon Oxidation via Co(IV) Species

Fate of Cobaltacycles in Cp*Co-Mediated C–H Bond Functionalization Catalysis: Cobaltacycles May Collapse upon Oxidation via Co(IV) Species

Deciphering the Role of Noncovalent Interactions in the Conformations of Dibenzo‐1,5‐dichalcogenocines

Synergy between Indoloquinolines and Ciprofloxacin: An Antibiofilm Strategy against Pseudomonas aeruginosa

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