A simple cobalt catalyst system for the efficient and regioselective cyclotrimerisation of alkynes

2005 ◽  
pp. 1474 ◽  
Author(s):  
Gerhard Hilt ◽  
Thomas Vogler ◽  
Wilfried Hess ◽  
Fabrizio Galbiati
Keyword(s):  
Cobalt Catalyst ◽  
Catalyst System

A Simple Cobalt Catalyst System for the Efficient and Regioselective Cyclotrimerization of Alkynes.

ChemInform ◽  
2005 ◽  
Vol 36 (32) ◽  
Author(s):  
Gerhard Hilt ◽  
Thomas Vogler ◽  
Wilfried Hess ◽  
Fabrizio Galbiati
Keyword(s):  
Cobalt Catalyst ◽  
Catalyst System

A Highly Active Cobalt Catalyst System for Kumada Biaryl Cross-Coupling

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1199-1202 ◽  
Author(s):  
Wenqin Wu ◽  
Hung Duong
Keyword(s):  
Room Temperature ◽  
Cobalt Catalyst ◽  
Cross Coupling ◽  
Catalyst System ◽  
Coupling Reactions ◽  
Short Reaction Time ◽  
Cross Coupling Reactions ◽  
Highly Active ◽  
Aryl Bromides ◽  
Wide Range

A highly active cobalt catalyst system has been developed for the cross-coupling reactions of arylmagnesium reagents and aryl bromides. In the presence of 1 mol% CoCl2, 2 mol% IPr·HCl and 2 mol% NaO t Bu, a wide range of (hetero)biaryls are prepared in 51–99% yields at room temperature within a short reaction time.

Pd/Cu-free Magnetic Cobalt Catalyst for C-N cross Coupling Reactions: Synthesis of Abemaciclib and Fedratinib

2021 ◽  
Author(s):  
Zahra Khorsandi ◽  
Abdol R. Hajipour ◽  
Mohammad R. Sarfjoua ◽  
Rajender S Varma
Keyword(s):  
Magnetic Nanoparticles ◽  
Functional Groups ◽  
Cobalt Catalyst ◽  
Cross Coupling ◽  
Catalyst System ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Nano Catalyst ◽  
Natural Ligands ◽  
Cobalt Species

Herein, the synthesis of a nano-catalyst system comprising magnetic nanoparticles as core and edible natural ligands bearings functional groups for supporting the cobalt species was accomplished. Subsequent to characterization, its...

Direct Observation of Chain Lengths and Conformations in Oligofluorene Distributions from Controlled Polymerization by Double Electron-Electron Resonance

2019 ◽  
Author(s):  
Dennis Bücker ◽  
Annika Sickinger ◽  
Julian D. Ruiz Perez ◽  
Manuel Oestringer ◽  
Stefan Mecking ◽  
...  
Keyword(s):  
Chain Length ◽  
Length Distribution ◽  
Catalyst System ◽  
Chain Conformation ◽  
Controlled Polymerization ◽  
Chain Length Distribution ◽  
Electron Resonance ◽  
Double Electron ◽  
The Individual ◽  
Double Electron Electron Resonance

Synthetic polymers are mixtures of different length chains, and their chain length and chain conformation is often experimentally characterized by ensemble averages. We demonstrate that Double-Electron-Electron-Resonance (DEER) spectroscopy can reveal the chain length distribution, and chain conformation and flexibility of the individual n-mers in oligo-(9,9-dioctylfluorene) from controlled Suzuki-Miyaura Coupling Polymerization (cSMCP). The required spin-labeled chain ends were introduced efficiently via a TEMPO-substituted initiator and chain terminating agent, respectively, with an in situ catalyst system. Individual precise chain length oligomers as reference materials were obtained by a stepwise approach. Chain length distribution, chain conformation and flexibility can also be accessed within poly(fluorene) nanoparticles.

Mechanistic Insights into Fe Catalyzed α-C-H Oxidations of Tertiary Amines

2019 ◽  
Author(s):  
Christopher J. Legacy ◽  
Frederick T. Greenaway ◽  
Marion Emmert
Keyword(s):  
Free Radical ◽  
Catalytic Mechanism ◽  
Catalyst System ◽  
Oxidation Products ◽  
Tertiary Amines ◽  
Catalyst Activation ◽  
Rate Determining Step ◽  
Fe Catalyst ◽  
Ligand Coordination ◽  
Rate Kinetics

We report detailed mechanistic investigations of an iron-based catalyst system, which allows the α-C-H oxidation of a wide variety of amines, including acyclic tertiary aliphatic amines, to afford dealkylated or amide products. In contrast to other catalysts that affect α-C-H oxidations of tertiary amines, the system under investigation employs exclusively peroxy esters as oxidants. More common oxidants (e.g. tBuOOH) previously reported to affect amine oxidations via free radical pathways do not provide amine α-C-H oxidation products in combination with the herein described catalyst system. Motivated by this difference in reactivity to more common free radical systems, the investigations described herein employ initial rate kinetics, kinetic profiling, Eyring studies, kinetic isotope effect studies, Hammett studies, ligand coordination studies, and EPR studies to shed light on the Fe catalyst system. The obtained data suggest that the catalytic mechanism proceeds through C-H abstraction at a coordinated substrate molecule. This rate-determining step occurs either at an Fe(IV) oxo pathway or a 2-electron pathway at a Fe(II) intermediate with bound oxidant. We further show via kinetic profiling and EPR studies that catalyst activation follows a radical pathway, which is initiated by hydrolysis of PhCO3 tBu to tBuOOH in the reaction mixture. Overall, the obtained mechanistic data support a non-classical, Fe catalyzed pathway that requires substrate binding, thus inducing selectivity for α-C-H functionalization.<br>

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