Bidentate Directing Groups: An Efficient Tool in C–H Bond Functionalization Chemistry for the Expedient Construction of C–C Bonds

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(3), P. 1788 - 1887

Published: Jan. 6, 2020

During the past decades, synthetic organic chemistry discovered that directing group assisted C–H activation is a key tool for expedient and siteselective construction of C–C bonds. Among various strategies, bidentate groups are now recognized as one most efficient devices selective functionalization certain positions due to fact its metal center permits fine, tunable, reversible coordination. The family permit types assistance be achieved, such N,N-dentate, N,O-dentate, N,S-dentate auxiliaries, which categorized based on coordination site. In this review, we broadly discuss bond reactions formation bonds with aid groups.

Language: Английский

---

C–H Activation: Toward Sustainability and Applications

ACS Central Science, Journal Year: 2021, Volume and Issue: 7(2), P. 245 - 261

Published: Feb. 2, 2021

Since the definition of "12 Principles Green Chemistry" more than 20 years ago, chemists have become increasingly mindful need to conserve natural resources and protect environment through judicious choice synthetic routes materials. The direct activation functionalization C–H bonds, bypassing intermediate functional group installation is, in abstracto, step atom economic, but numerous factors still hinder sustainability large-scale applications. In this Outlook, we highlight research areas seeking overcome challenges activation: pursuit abundant metal catalysts, avoidance static directing groups, replacement oxidants, introduction bioderived solvents. We close by examining progress made subfield aryl borylation from its origins, highly efficient precious Ir-based systems, emerging 3d catalysts. future growth field will depend on industrial uptake, thus urge researchers strive toward sustainable activation.

Language: Английский

---

The Fluorination of C−H Bonds: Developments and Perspectives

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(42), P. 14824 - 14848

Published: Feb. 13, 2019

Abstract This Review summarizes advances in fluorination by C(sp 2 )−H and 3 activation. Transition‐metal‐catalyzed approaches championed palladium have allowed the installation of a fluorine substituent at ) sites, exploiting reactivity high‐oxidation‐state transition‐metal fluoride complexes combined with use directing groups (some transient) to control site stereoselectivity. The large majority known methods employ electrophilic reagents, but combining nucleophilic source an oxidant appeared. External ligands proven be effective for directed weakly coordinating auxiliaries, thereby enabling over reactivity. Methods relying on formation radical intermediates are complementary transition‐metal‐catalyzed processes as they allow undirected fluorination. To date, C−H fluorinations mainly N−F reagents unique Mn III ‐catalyzed oxidative using has been developed. Overall, field late‐stage progressed much more slowly, state play explaining why 18 F‐fluorination is still its infancy.

Language: Английский

---

Installing the “magic methyl” – C–H methylation in synthesis

Chemical Society Reviews, Journal Year: 2021, Volume and Issue: 50(9), P. 5517 - 5563

Published: Jan. 1, 2021

Following notable cases of remarkable potency increases in methylated analogues lead compounds, this review documents the state-of-the-art C–H methylation technology.

Language: Английский

---

Overcoming the Limitations of γ- and δ-C–H Arylation of Amines through Ligand Development

Journal of the American Chemical Society, Journal Year: 2018, Volume and Issue: 140(51), P. 17884 - 17894

Published: Nov. 30, 2018

L,X-Type transient directing groups (TDGs) based on a reversible imine linkage have emerged as broadly useful tools for C–H activation of ketones and free amines. However, competitive binding interactions among multiple reaction components (TDG itself, substrate, substrate–TDG adduct) with the palladium catalyst often lead to formation unreactive complexes, rendering ligand development extremely challenging. Herein, we report finding versatile 2-pyridone ligands that addresses these problems significantly improves γ-methylene arylation alkyl amines, extending coupling partners wide range medicinally important heteroaryl iodides even previously bromides. The combination an appropriate group pyridone has also enabled δ-arylation Notably, our design reveals importance matching size Pd-chelation different palladacycles generated from γ- δ-C–H bonds: TDGs coordinate Pd(II) form six-membered chelate are selective toward γ-C–H bonds, whereas via five-membered tend activate bonds. These findings provide avenue developing protecting functionalization using strategy.

Language: Английский

---

P^III‐Chelation‐Assisted Indole C7‐Arylation, Olefination, Methylation, and Acylation with Carboxylic Acids/Anhydrides by Rhodium Catalysis

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 58(5), P. 1504 - 1508

Published: Dec. 6, 2018

Rhodium-catalyzed C7-selective decarbonylative arylation, olefination, and methylation of indoles with carboxylic acids or anhydrides by C-H C-C bond activation have been developed. Furthermore, C7-acylation products can also be generated selectively at a lower reaction temperature in the developed system. The key to high reactivity regioselectivity this transformation is appropriate choice an indole N-PtBu2 chelation-assisted group. This method has many advantages, including easy access removal directing group, use cheap widely available coupling agents, no requirement external ligand oxidant, broad substrate scope, efficiency, formation sole regioisomer.

Language: Английский

---

Transient imines as ‘next generation’ directing groups for the catalytic functionalisation of C–H bonds in a single operation

Organic & Biomolecular Chemistry, Journal Year: 2018, Volume and Issue: 16(25), P. 4582 - 4595

Published: Jan. 1, 2018

C-H functionalisation promises a paradigm shift in synthetic planning. However, the additional steps often required to install and remove directing groups currently detract from efficiency. The strategy of reversible installation group via an imine linkage has recently emerged, with formed hydrolysed situ. Such transient can promote transition metal catalysed unactivated bonds aldehydes, ketones amines. This approach removes usually for covalent use catalytic quantities forming component. review updates rapidly developing field on sp2 sp3 carbon centres, form new C-C C-X bonds. We focus structures as mono or bidentate coordinating various catalysts.

Language: Английский

---

Role of hexafluoroisopropanol in C–H activation

Reaction Chemistry & Engineering, Journal Year: 2018, Volume and Issue: 4(2), P. 244 - 253

Published: Oct. 30, 2018

HFIP has developed immense importance in the C–H functionalization methodology. Both reactivity and selectivity have been vastly improved using whose H-bonding to substrate facilitates accelerates activation. This review summarizes chronological development of evolution activation along with important mechanistic details.

Language: Английский

---

Beyond Friedel and Crafts: Directed Alkylation of C−H Bonds in Arenes

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 58(22), P. 7202 - 7236

Published: Aug. 14, 2018

Abstract Alkylation of arenes is one the most fundamental transformations in chemical synthesis and leads to privileged scaffolds many areas science. Classical methods for introduction alkyl groups are mostly based on Friedel–Crafts reaction, radical additions, metalation, or prefunctionalization arene: these methods, however, suffer from limitations scope, efficiency, selectivity. Moreover, they innate reactivity starting arene, favoring alkylation at a certain position rendering chains other positions much more challenging. This can be addressed by use directing group that facilitates, presence metal catalyst, regioselective C−H bond. These directed alkylations bonds will comprehensively summarized this Review.

Language: Английский

---

Transient Ligand‐Enabled Transition Metal‐Catalyzed C−H Functionalization

ChemSusChem, Journal Year: 2019, Volume and Issue: 12(13), P. 2955 - 2969

Published: April 8, 2019

Transition metal-catalyzed C-H bond functionalization is among the most efficient and powerful strategies in synthetic organic chemistry to derivatize otherwise inert sites of molecules for construction C-C C-heteroatom bonds. However, additional steps are often required install directing groups realize selective substrates. These tedious run counter step-economical nature activation. In contrast, direct substrate by using transient ligands avoids unnecessary pre-functionalization This Minireview provides a short overview major progress made this field at sp2 sp3 carbon centers with different working modes, including covalent, hydrogen, ionic

Language: Английский

---