N-Heterocyclic Carbene Complexes in C–H Activation Reactions

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(4), P. 1981 - 2048

Published: Jan. 22, 2020

In this contribution, we provide a comprehensive overview of C-H activation methods promoted by NHC-transition metal complexes, covering the literature since 2002 (the year first report on metal-NHC-catalyzed activation) through June 2019, focusing both NHC ligands and methods. This review covers reactions catalyzed group 8 to 11 NHC-metal complexes. Through discussing role in promoting challenging methods, reader is provided with an important area its crucial forging carbon-carbon carbon-heteroatom bonds directly engaging ubiquitous bonds.

Language: Английский

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BIAN‐NHC Ligands in Transition‐Metal‐Catalysis: A Perfect Union of Sterically Encumbered, Electronically Tunable N‐Heterocyclic Carbenes?

Chemistry - A European Journal, Journal Year: 2020, Volume and Issue: 27(14), P. 4478 - 4499

Published: Sept. 29, 2020

The discovery of NHCs (NHC = N-heterocyclic carbenes) as ancillary ligands in transition-metal-catalysis ranks one the most important developments synthesis and catalysis. It is now well-recognized that strong σ-donating properties along with ease scaffold modification a steric shielding N-wingtip substituents around metal center enable dramatic improvements catalytic processes, including reactions are not possible using other ligands. In this context, although classical based on imidazolylidene imidazolinylidene ring systems well-established, recently tremendous progress has been made development applications BIAN-NHC (BIAN bis(imino)acenaphthene) class enhanced reactivity BIAN-NHCs direct result combination electronic collectively allow for major expansion scope processes can be accomplished NHCs. take advantage (1) stronger σ-donation, (2) lower lying LUMO orbitals, (3) presence an extended π-system, (4) rigid backbone pushes closer to by buttressing effect, thus resulting significantly improved control air-stability BIAN-NHC-metal complexes at low oxidation state. Acenaphthoquinone precursor enables facile modification, first time high yielding unsymmetrical unique properties. Overall, results highly attractive, easily accessible bring advances emerge leading practical alternative various aspects catalysis, cross-coupling C-H activation endeavors.

Language: Английский

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IPr# – highly hindered, broadly applicable N-heterocyclic carbenes

Chemical Science, Journal Year: 2021, Volume and Issue: 12(31), P. 10583 - 10589

Published: Jan. 1, 2021

We report novel, sterically-bulky, easily-accessible NHC ligands based on the hash peralkylation concept. The new have been commercialized in collaboration with Millipore Sigma: IPr#HCl, 915653; Np#HCl; 915912; BIAN-IPr#HCl, 916420.

Language: Английский

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Advances in the Synthesis and Applications of N-Heterocyclic Carbene Metal Complexes with a Focus on the Weak Base Route

Organometallics, Journal Year: 2023, Volume and Issue: 42(19), P. 2692 - 2730

Published: Sept. 21, 2023

N-heterocyclic carbene (NHC) ligands have evolved from being simple lab curiosities to tertiary phosphine mimics finally take center stage as unique supporting in organometallic chemistry, homogeneous catalysis, and more recently medicinal chemistry materials science applications. Some of these aspects are presented here a perspective researchers that been fascinated by the area for quite some time.

Language: Английский

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Non-Classical Amide Bond Formation: Transamidation and Amidation of Activated Amides and Esters by Selective N–C/O–C Cleavage

Synthesis, Journal Year: 2020, Volume and Issue: 52(18), P. 2579 - 2599

Published: May 15, 2020

In the past several years, tremendous advances have been made in non-classical routes for amide bond formation that involve transamidation and amidation reactions of activated amides esters. These new methods enable extremely valuable bonds via transition-metal-catalyzed, transition-metal-free, or metal-free pathways by exploiting chemoselective acyl C–X (X = N, O) cleavage under mild conditions. a broadest sense, these overcome formidable challenge activating C–N/C–O esters rationally tackling nN → π*C=O delocalization nO donation this account, we summarize recent remarkable development synthesis with focus on (1) transition-metal/NHC-catalyzed activation, (2) transition-metal-free highly selective bonds, (3) acyl-transfer reagents, (4) other emerging methods. 1 Introduction 2 Transamidation Amides 2.1 Metal–NHC Catalysis (Pd–NHC, Ni–NHC) 2.2 Transition-Metal-Free Tetrahedral Intermediates 2.3 Reductive 2.4 New Acyl-Transfer Reagents 2.5 Tandem Transamidations 3 Amidation Esters 3.1 3.2 3.3 4 Other Mechanisms 5 Conclusions Outlook

Language: Английский

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N-Heterocyclic carbene complexes enabling the α-arylation of carbonyl compounds

Chemical Communications, Journal Year: 2021, Volume and Issue: 57(36), P. 4354 - 4375

Published: Jan. 1, 2021

The considerable importance of α-arylated carbonyl compounds, which are widely used in the pharmaceutical industry, has prompted efficient synthetic strategies for their preparation.

Language: Английский

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Synthesis, Structure, and Anticancer Activity of Symmetrical and Non-symmetrical Silver(I)-N-Heterocyclic Carbene Complexes

Applied Biochemistry and Biotechnology, Journal Year: 2020, Volume and Issue: 191(3), P. 1171 - 1189

Published: Jan. 31, 2020

Language: Английский

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Thiazol-2-ylidenes as N-Heterocyclic carbene ligands with enhanced electrophilicity for transition metal catalysis

Communications Chemistry, Journal Year: 2022, Volume and Issue: 5(1)

Published: May 6, 2022

Over the last 20 years, N-heterocyclic carbenes (NHCs) have emerged as a dominant direction in ligand development transition metal catalysis. In particular, strong σ-donation combination with tunable steric environment make NHCs to be among most common ligands used for C-C and C-heteroatom bond formation. Herein, we report study on electronic properties of thiazol-2-ylidenes. We demonstrate that thiazole heterocycle enhanced π-electrophilicity result class highly active carbene electrophilic cyclization reactions form valuable oxazoline heterocycles. The evaluation steric, electron-donating π-accepting well structural characterization coordination chemistry is presented. This mode catalysis can applied late-stage drug functionalization furnish attractive building blocks medicinal chemistry. Considering key role ligands, anticipate N-aryl thiazol-2-ylidenes will broad interest modern chemical synthesis.

Language: Английский

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Recent Advances on N‐Heterocyclic Carbene‐Palladium‐catalyzed Heck Reaction

ChemistrySelect, Journal Year: 2022, Volume and Issue: 7(4)

Published: Jan. 24, 2022

Abstract Heck reaction is a synthetically important C−C bond forming coupling happening between alkenes and aryl or vinyl halides catalyzed by palladium complexes to form substituted alkenes. This review focusses on the recent advancements in development of various types N‐heterocyclic carbene (NHC) ligands coupled with catalyst that can catalyze Mizoroki‐Heck reactions. NHC have unique characteristic nature, hence widely used homogeneous catalysis. Generally, they good σ‐donating sparingly π‐accepting properties. It more stable shows superior properties when compared phosphine under prominent studies. Thus, stabilize large extend metal oxidation states high thermal stability. Most catalysts outlined here provide efficient green synthetic route for formations. The encompasses literature from 2017 2021.

Language: Английский

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PEPPSI-Pd-NHC catalyzed Suzuki-Miyaura cross-coupling reactions in aqueous media

Tetrahedron, Journal Year: 2019, Volume and Issue: 75(15), P. 2306 - 2313

Published: March 5, 2019

Language: Английский

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