scholarly journals Bifunctional Ligand-Assisted Cu-Catalyzed Intermolecular Cyclo-hexenone γ‑C(sp3)-H Amination: Controlled Synthesis of p-Aminophenols

2021 ◽  
Author(s):  
Xin Zhao ◽  
Fang Yang ◽  
Qian-Qian Zhou ◽  
Zou Shaoyu ◽  
Zi-Sheng Chen ◽  
...  
Keyword(s):  
Catalytic System ◽  
Amide Group ◽  
Practical Approach ◽  
Controlled Synthesis ◽  
Bifunctional Ligand ◽  
Environmental Friendly ◽  
Bifunctional Ligands ◽  
Site Selective

Abstract A 1,10-phenanthroline-type bifunctional ligand has been developed for Cu catalyzed direct γ-C(sp3)-H amination with intermolecular anilines. Stabilizing N-centered radicals via amide group installed on the bifunctional ligands, a new catalytic system for site-selective γ-C(sp3)-H amination to synthesize p-aminophenols was established. The economical and practical approach by using oxygen as the terminal oxidant was mild and environmental friendly.

scholarly journals Site-selective Amide Functionalization by Catalytic Azoline Engrafting

2021 ◽  
Author(s):  
Wyatt Powell ◽  
Garrett Evenson ◽  
Maciej Walczak
Keyword(s):  
Natural Products ◽  
Catalytic System ◽  
High Selectivity ◽  
High Efficiency ◽  
Unmet Need ◽  
Direct Conversion ◽  
Amide Group ◽  
Site Selective ◽  
Selection Of ◽  
General Method

Amide activation is a challenging transformation due to the stabilizing effect of the amide group. While enzymes can be considered as prototypical systems that have evolved to achieve high selectivity and specificity, small-molecule catalysts that functionalize the amide group may accommodate a much larger selection of substrates but currently re-main scarce. Here, by combining the desired features from both catalytic regimes we designed an artificial cyclodehy-dratase, a catalytic system for site-selective modification of peptides and natural products by engrafting heterocyclic into their scaffolds. The catalytic system features molybdenum(VI) center that was decorated with a sterically congest-ed tripod ligand. The optimized catalyst can introduce azolines into small molecules, natural products, and oligopeptides with high efficiency and minimal waste. We further demonstrate the utility of the new protocol in direct func-tionalization of a single amide group in the presence of up to seven other chemically similar positions, and direct conversion into amines and thioamides. This new mechanistic paradigm may address an unmet need for a general method for selective and sustainable functionalization of peptides and natural products.

Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C–H Activation

2020 ◽  
Author(s):  
Chang-Sheng Wang ◽  
Sabrina Monaco ◽  
Anh Ngoc Thai ◽  
Md. Shafiqur Rahman ◽  
Chen Wang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Lewis Acid ◽  
Hydrogen Transfer ◽  
Acid Catalysis ◽  
Rate Limiting Step ◽  
Site Selectivity ◽  
Set Up ◽  
Site Selective ◽  
First Time ◽  
Rate Limiting

A catalytic system comprised of a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic system for analogous transformations, the present catalytic system not only feature convenient set up using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp), but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Mechanistic stidies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkyl(carbamoyl)cobalt intermediate.

Differentiation and Functionalization of Adjacent, Remote C–H Bonds

2019 ◽  
Author(s):  
Hang Shi ◽  
Lu Yi ◽  
Jiang Weng ◽  
Katherine Bay ◽  
Xiangyang Chen ◽  
...  
Keyword(s):  
Catalytic System ◽  
Functional Group ◽  
Hydrocinnamic Acid ◽  
Molecular Architectures ◽  
Site Selective ◽  
Developing Strategies

<p>Site-selective functionalizations of C–H bonds will ultimately afford chemists transformative tools for editing and constructing complex molecular architectures<sup>1-4</sup>. Towards this goal, developing strategies to activate C–H bonds that are distal from a functional group is essential<sup>4-6</sup>. In this context, distinguishing remote C–H bonds on adjacent carbon atoms is an extraordinary challenge due to the lack of electronic or steric bias between the two positions. Herein, we report the design of a catalytic system leveraging a remote directing template and a transient norbornene mediator to selectively activate a previously inaccessible remote C–H bond that is one bond further away. The generality of this approach has been demonstrated with a range of heterocycles, including a complex anti-leukemia agent, and hydrocinnamic acid substrates.</p>

Versatile Catalytic System for the Large-Scale and Controlled Synthesis of Single-Wall, Double-Wall, Multi-Wall, and Graphene Carbon Nanostructures

2009 ◽  
Vol 21 (22) ◽  
pp. 5491-5498 ◽  
Author(s):  
Enkeleda Dervishi ◽  
Zhongrui Li ◽  
Fumiya Watanabe ◽  
Aurelie Courte ◽  
Abhijit Biswas ◽  
...  
Keyword(s):  
Catalytic System ◽  
Carbon Nanostructures ◽  
Large Scale ◽  
Controlled Synthesis ◽  
Double Wall

Photocatalytic site-selective C–H difluoroalkylation of aromatic aldehydes

2020 ◽  
Vol 56 (10) ◽  
pp. 1497-1500 ◽  
Author(s):  
Wei-Ke Tang ◽  
Fei Tang ◽  
Jun Xu ◽  
Qi Zhang ◽  
Jian-Jun Dai ◽  
...  
Keyword(s):  
Aromatic Aldehyde ◽  
Catalytic System ◽  
Aromatic Aldehydes ◽  
System P ◽  
Site Selective

The direct photocatalyzed site-selective CAr–H difluoroalkylation of aromatic aldehyde derivatives has been accomplished using a newly explored catalytic system.

scholarly journals Development of a Simple Removable Aliphatic Template for Remote Meta-Selective C−H Functionalization: Experimental and Computational Studies

2020 ◽  
Author(s):  
Perla Ramesh ◽  
Chinnabattigalla Sreenivasulu ◽  
Koteswara Rao Gorantla ◽  
Bhabani Mallik ◽  
Gedu Satyanarayana
Keyword(s):  
Column Chromatography ◽  
Future Development ◽  
Practical Approach ◽  
Computational Studies ◽  
Mild Conditions ◽  
The Future ◽  
Olefin Coupling ◽  
Site Selective ◽  
First Time

Herein, we have successfully unveiled a simple and inexpensive removable aliphatic template as an effective DG template in promoting remote <i>meta</i>-C−H olefination of arenes for the first time. Remarkably, the template was achieved in excellent yields in just two steps and without column chromatography purification. The protocol is an efficient, economical and practical approach in achieving <i>meta</i>-C−H olefination in good to excellent isolated yields and high levels of <i>meta</i>-selectivity under mild conditions. A wide variety of substituted arenes and olefin coupling partners are well tolerated in this reaction. Moreover, the aliphatic template is found to be advantageous due to its easy synthesis, easy installation/removal, and recycle. We believe that this strategy offers new opportunities for the future development of new DG templates to promote site-selective C−H functionalizations.

Regio/site-selective alkylation of substrates containing a cis-, 1,2- or 1,3-diol with ferric chloride and dipivaloylmethane as the catalytic system

2020 ◽  
Vol 22 (4) ◽  
pp. 1139-1144
Author(s):  
Jian Lv ◽  
Yu Liu ◽  
Jia-Jia Zhu ◽  
Dapeng Zou ◽  
Hai Dong
Keyword(s):  
Catalytic System ◽  
Ferric Chloride ◽  
System P ◽  
Selective Alkylation ◽  
Site Selective

We reported the regio/site-selective alkylation of diols and polyols with FeCl3 as a key catalyst and confirmed the mechanism.

The development of an environmental friendly catalytic system for the conversion of olefins

1997 ◽  
Vol 36 (4) ◽  
pp. 451-460 ◽  
Author(s):  
Luc R. Martens ◽  
J.P. Verduijn ◽  
G.M. Mathys
Keyword(s):  
Catalytic System ◽  
Environmental Friendly

Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C–H Activation

2020 ◽  
Author(s):  
Chang-Sheng Wang ◽  
Sabrina Monaco ◽  
Anh Ngoc Thai ◽  
Md. Shafiqur Rahman ◽  
Chen Wang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Lewis Acid ◽  
Hydrogen Transfer ◽  
Acid Catalysis ◽  
Rate Limiting Step ◽  
Site Selectivity ◽  
Set Up ◽  
Site Selective ◽  
First Time ◽  
Rate Limiting

A catalytic system comprised of a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic system for analogous transformations, the present catalytic system not only feature convenient set up using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp), but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Mechanistic stidies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkyl(carbamoyl)cobalt intermediate.

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