Palladium–Carbon π-Bonded Complexes

Espinet, Pablo; Albéniz, Ana C.

doi:10.1016/b0-08-045047-4/00104-7

Cited by 10 publications

(7 citation statements)

References 685 publications

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“…[120] Another characteristic of the dialkylbiaryl phosphane ligands which is believed to promote catalyst stability and increase electron density at the metal center is the possibility of palladium-arene interactions between the metal atom and the lower ring of the ligand (see I). [121] Such interactions have been observed in the X-ray crystal structures of a number of palladiumbiaryl phosphane complexes [27][28][29][122][123][124][125] and even in an oxidative addition complex with methyl triflate. [126] Obtaining experimental information on the importance of these interactions in the catalytically active species has proven more difficult.…”

Section: Structure Of the Dialkylbiaryl Phosphane Ligandsmentioning

confidence: 86%

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

2008

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Palladium-catalyzed amination of aryl halides has undergone rapid development in the last 12 years. This has been largely driven by implementation of new classes of ligands. Biaryl phosphines have proven to provide especially active catalysts in this context. This review discusses the applications that these catalysts have found in C-N cross-coupling in heterocycle synthesis, pharmaceuticals, materials science and natural product synthesis.

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Section: Structure Of the Dialkylbiaryl Phosphane Ligandsmentioning

confidence: 86%

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

2008

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“…The potential of the ExIn approach to prepare substituted stilbenes that are of interest as scaffolds in medicinal chemistry and drug design (see, for example, resveratrol and combretastatin A-4, Scheme A) was investigated . Insertion reactions of allenes into Pd–C bonds are known, − as are the resultant η 3 -allyl complexes which have been used in organic synthesis, − so ExIn synthetic protocols could provide access to a range of alkenes, including stilbenes.…”

Section: Introductionmentioning

confidence: 99%

Palladium-Mediated CO₂ Extrusion Followed by Insertion of Allenes: Translating Mechanistic Studies to Develop a One-Pot Method for the Synthesis of Alkenes

et al. 2022

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= H) is reported. This is an isoelectronic variant of CO 2 extrusion−insertion (ExIn) reactions previously developed using heterocumulenes for the synthesis of thioamides (from isothiocyanates, RNCS), amidines (from carbodiimides, RNCNR), and amides (from isocyanates, RNCO). Evidence that the key aryl-palladium intermediate reacts to form a stable allyl-palladium product via insertion of the allene at the C2 position that enables the synthesis of alkenes was provided by a combination of gas-phase multistage mass spectrometry (MS n ) experiments and condensed-phase monitoring using 1 H NMR spectroscopy as well as theoretical computational data. Isolation and X-ray crystallographic analysis of the salt [(phen)Pd(CH 2 CH(Ar)CHPh)] + (CF 3 CO 2 − ) (where Ar = 2,6dimethoxyphenyl) confirmed insertion of the allene at the C2 position and revealed a syn relationship between the two aryl groups. A survey of different hydrogen sources to promote the removal of palladium from the alkene product revealed that NaBH 4 provides the highest yield and with the Z-alkene as the major isomer.

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“…The η 5 -pentamethylcyclopentadienyl ligandor Cp*in spite of the abundant literature is often considered as a “robust”, sterically and electronically stabilizing , ligand in its use in catalysts . If in specific cases the endo migration of a hydrido ligand to Cp* has been reported in the case of a bis-pyridine chelate of Rh(III), the literature is rather silent on occurrences of explicit reactions of the Cp* ligand with {κ N ,κ C } − heterochelating ligands in metallacycles .…”

Section: Introductionmentioning

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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Palladium–Carbon π-Bonded Complexes

Cited by 10 publications

References 685 publications

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

Palladium-Mediated CO₂ Extrusion Followed by Insertion of Allenes: Translating Mechanistic Studies to Develop a One-Pot Method for the Synthesis of Alkenes

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

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Palladium–Carbon π-Bonded Complexes

Cited by 10 publications

References 685 publications

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

Palladium-Mediated CO2 Extrusion Followed by Insertion of Allenes: Translating Mechanistic Studies to Develop a One-Pot Method for the Synthesis of Alkenes

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

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Palladium-Mediated CO₂ Extrusion Followed by Insertion of Allenes: Translating Mechanistic Studies to Develop a One-Pot Method for the Synthesis of Alkenes