Imine as a Linchpin Approach for Distal C(sp2)–H Functionalization

2020 ◽  
Author(s):  
Sukdev Bag ◽  
Sadhan Jana ◽  
Sukumar Pradhan ◽  
Suman Bhowmick ◽  
Nupur Goswami ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Activation ◽  
Bond Formation ◽  
Ancillary Ligand ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Directing Group ◽  
Covalently Linked ◽  
Complex Organic ◽  
Post Functionalization

<p>Despite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing group (DG) served as an ancillary ligand to ensure proximal <i>ortho</i>-, distal <i>meta</i>- and <i>para</i>-C-H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. We introduce here a transient directing group for distal C(<i>sp<sup>2</sup></i>)-H functionalization <i>via</i> reversible imine formation. By overruling facile proximal C-H bond activation by imine-<i>N</i> atom, a suitably designed pyrimidine-based transient directing group (TDG) successfully delivered selective distal C-C bond formation. Application of this transient directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the distal position has been explored.</p>

Imine as a Linchpin Approach for Distal C(sp2)–H Functionalization

2020 ◽  
Author(s):  
Sukdev Bag ◽  
Sadhan Jana ◽  
Sukumar Pradhan ◽  
Suman Bhowmick ◽  
Nupur Goswami ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Activation ◽  
Bond Formation ◽  
Ancillary Ligand ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Directing Group ◽  
Covalently Linked ◽  
Complex Organic ◽  
Post Functionalization

<p>Despite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing group (DG) served as an ancillary ligand to ensure proximal <i>ortho</i>-, distal <i>meta</i>- and <i>para</i>-C-H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. We introduce here a transient directing group for distal C(<i>sp<sup>2</sup></i>)-H functionalization <i>via</i> reversible imine formation. By overruling facile proximal C-H bond activation by imine-<i>N</i> atom, a suitably designed pyrimidine-based transient directing group (TDG) successfully delivered selective distal C-C bond formation. Application of this transient directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the distal position has been explored.</p>

scholarly journals Imine as a linchpin approach for meta-C–H functionalization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sukdev Bag ◽  
Sadhan Jana ◽  
Sukumar Pradhan ◽  
Suman Bhowmick ◽  
Nupur Goswami ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Activation ◽  
Bond Formation ◽  
Ancillary Ligands ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Directing Group ◽  
Covalently Linked ◽  
Complex Organic ◽  
Post Functionalization

AbstractDespite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing groups (DGs) served as ancillary ligands to ensure ortho-, meta- and para-C–H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. Here we report a temporary directing group (TDG) for meta-C–H functionalization via reversible imine formation. By overruling facile ortho-C–H bond activation by imine-N atom, a suitably designed pyrimidine-based TDG successfully delivered selective meta-C–C bond formation. Application of this temporary directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the meta position has been explored.

scholarly journals Recent Developments in Palladium-Catalysed Non-Directed C–H Bond Activation in Arenes

Synthesis ◽  
2019 ◽  
Vol 51 (03) ◽  
pp. 643-663 ◽  
Author(s):  
Kåre Jørgensen ◽  
M. Fernández-Ibáñez ◽  
Sindhu Kancherla
Keyword(s):  
Aromatic Compounds ◽  
Bond Activation ◽  
Bond Formation ◽  
Short Review ◽  
The Past ◽  
New Approaches ◽  
Site Selectivity ◽  
Recent Developments ◽  
Directing Group

Over the past decades, organic chemists have focussed on developing new approaches to directed C–H functionalisations, where the site selectivity is steered by the presence of a directing group (DG). Nonetheless, in recent years, more and more non-directed strategies are being developed to circumvent the requisite directing group, making C–H functionalisations more generic. This short review focuses on the latest developments in palladium-catalysed non-directed C–H functionalisations of aromatic compounds.1 Introduction2 C–C Bond Formation2.1 C–H Arylation2.2 C–H Alkylation2.3 C–H Alkenylation2.4 C–H Carbonylation3 C–Heteroatom Bond Formation3.1 C–O Bond Formation3.2 C–N Bond Formation3.3 C–S Bond Formation4 Conclusion

Electrochemical Radical C(sp3)-H Arylation of Xanthenes with Electron-Rich Arenes

2022 ◽  
Author(s):  
Bin Wei ◽  
Jing-Hao Qin ◽  
Yong-Zheng Yang ◽  
Ye-Xiang Xie ◽  
Xuan-Hui Ouyang ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Formation ◽  
Carbon Bond ◽  
Carbon Carbon Bond ◽  
Complex Organic

C(sp3)-H arylation has recently emerged as a powerful straegy for complex organic molecules synthesis through a new carbon-carbon bond formation. We herein describe an efficient electrochemical C(sp3)-H arylation of xanthenes...

Reversing Conventional Site-Selectivity in C(sp3)-H Bond Activation

2018 ◽  
Author(s):  
guoqin xia ◽  
pritha verma ◽  
jiang weng ◽  
Luoyan Liu ◽  
Ziqiang Li ◽  
...  
Keyword(s):  
Bond Activation ◽  
Aliphatic Alcohols ◽  
Group Design ◽  
Site Selectivity ◽  
Directing Group

Distal C(sp<sup>3</sup>)–H bonds of aliphatic alcohols are preferentially activated over proximate C(sp<sup>3</sup>)–H bonds through a combination of directing group design and ligand acceleration.

1.12 Intermolecular Radical C—H Functionalization

2021 ◽  
Author(s):  
M. Bietti ◽  
F. Dénès
Keyword(s):  
Hydrogen Atom ◽  
Transition Metal ◽  
Bond Formation ◽  
Metal Catalysts ◽  
Hydrogen Atom Transfer ◽  
Transition Metal Catalysts ◽  
Radical Species ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Selection Of

AbstractThe generation of carbon-centered radicals via intermolecular hydrogen-atom transfer (HAT) from C—H bonds to an abstracting species (HAT reagent) represents a significant challenge in terms of reactivity, site-selectivity and stereoselectivity. The radical species resulting from such a transfer can then engage in carbon—carbon or carbon—heteroatom bond formation, possibly through the intervention of transition-metal catalysts, leading to a variety of functionalized products. This chapter aims to provide the reader with useful guidelines to understand, predict, and design selective radical transformations based upon initial HAT from a C—H bond coupled to different radical-capture strategies. A selection of examples that illustrate different approaches to implement HAT reactions in synthetically useful procedures are presented.

scholarly journals Metal Nanoparticles as Sustainable Tools for C–N Bond Formation via C–H Activation

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4106
Author(s):  
Federica Valentini ◽  
Oriana Piermatti ◽  
Luigi Vaccaro
Keyword(s):  
Metal Nanoparticles ◽  
Natural Product ◽  
Heterogeneous Catalysts ◽  
Organic Molecules ◽  
Bond Formation ◽  
Environmental Costs ◽  
Highly Active ◽  
Active Mechanism ◽  
Active Metal ◽  
Complex Organic

The design of highly active metal nanoparticles to be employed as efficient heterogeneous catalysts is a key tool for the construction of complex organic molecules and the minimization of their environmental costs. The formation of novel C–N bonds via C–H activation is an effective atom-economical strategy to access high value materials in pharmaceuticals, polymers, and natural product production. In this contribution, the literature of the last ten years on the use of metal nanoparticles in the processes involving direct C–N bond formation will be discussed. Where possible, a discussion on the role and influence of the support used for the immobilization and/or the metal chosen is reported. Particular attention was given to the description of the experiments performed to elucidate the active mechanism.

A Review on Sulfur-Directed C−H Bond Activation

2020 ◽  
Vol 17 ◽  
Author(s):  
Xuchong Tang ◽  
Yingwei Zhao
Keyword(s):  
Transition Metal ◽  
Electron Donor ◽  
Bond Activation ◽  
Bond Formation ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Directing Group ◽  
Metal Catalyzed ◽  
Sulfur Containing

: Transition-metal-catalyzed C−H bond activation employing a directing group is becoming a powerful tool to access C−C or C−hetero bond formation. Oxygen and nitrogen atoms are commonly applied as the electron donor for these directing groups. In contrast, there are only few studies on sulfur-containing groups, probably due to their toxicity to transition-metal catalysts. Nowadays a large amount of C−H activation reactions directed by sulfur-containing auxiliary groups have been successfully achieved. Because these groups can be facilely removed or modified in situ or in further steps, they are of great value in creative synthetic strategies. This paper reviews recent advances in the studies using thioether, thiol/thiophenol/disulfide, sulfoxide, and thiocarbonyl as directing groups for intermolecular C−H functionalizations as well as intramolecular oxidative annulations.

Reversing Conventional Site-Selectivity in C(sp3)-H Bond Activation

2018 ◽  
Author(s):  
guoqin xia ◽  
pritha verma ◽  
jiang weng ◽  
Luoyan Liu ◽  
Ziqiang Li ◽  
...  
Keyword(s):  
Bond Activation ◽  
Aliphatic Alcohols ◽  
Group Design ◽  
Site Selectivity ◽  
Directing Group

Distal C(sp<sup>3</sup>)–H bonds of aliphatic alcohols are preferentially activated over proximate C(sp<sup>3</sup>)–H bonds through a combination of directing group design and ligand acceleration.

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