Mild metal-catalyzed C–H activation: examples and concepts

Chemical Society Reviews, Journal Year: 2016, Volume and Issue: 45(10), P. 2900 - 2936

Published: Jan. 1, 2016

C–H Activation reactions that proceed under mild conditions are more attractive for applications in complex molecule synthesis. Mild transformations reported since 2011 reviewed and the different concepts strategies have enabled their mildness discussed.

Language: Английский

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Cobalt-Catalyzed C–H Activation

ACS Catalysis, Journal Year: 2015, Volume and Issue: 6(2), P. 498 - 525

Published: Nov. 24, 2015

Catalytic C–H activation has emerged as a powerful tool for sustainable syntheses. In the recent years, notable success was achieved with development of cobalt-catalyzed functionalizations either in situ generated or single-component cobalt-complexes under mild reaction conditions. Herein, progress field organometallic is reviewed until November 2015.

Language: Английский

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Transition-Metal-Catalyzed Cross-Couplings through Carbene Migratory Insertion

Chemical Reviews, Journal Year: 2017, Volume and Issue: 117(23), P. 13810 - 13889

Published: Nov. 1, 2017

Transition-metal-catalyzed cross-coupling reactions have been well-established as indispensable tools in modern organic synthesis. One of the major research goals area is expanding scope coupling partners. In past decade, diazo compounds (or their precursors N-tosylhydrazones) emerged nucleophilic partners C-C single bond or C═C double formations transition-metal-catalyzed reactions. This type reaction involves following general steps. First, organometallic species generated by various processes, including oxidative addition, transmetalation, cyclization, cleavage, and C-H activation. Subsequently, reacts with substrate to generate metal carbene intermediate, which undergoes rapid migratory insertion form a bond. The new from may undergo transformations. carbene-based has proven be general: transition metals Pd, Cu, Rh, Ni, Co, Ir are effective catalysts; also extended substrates other than compounds; cascade processes devised based on insertion. review will summarize achievements made this field since 2001.

Language: Английский

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Substrate Activation Strategies in Rhodium(III)-Catalyzed Selective Functionalization of Arenes

Accounts of Chemical Research, Journal Year: 2015, Volume and Issue: 48(4), P. 1007 - 1020

Published: April 6, 2015

The possibility of developing new methods for the efficient construction organic molecules via disconnections other than traditional functional group transformations has driven interest in direct functionalization C-H bonds. ubiquity bonds makes such attractive, but they also pose several challenges. first is reactivity and selectivity To achieve this, directing groups (DGs) are often installed that can enhance effective concentration catalyst, leading to thermodynamically stable metallacyclic intermediates. However, presence a pendant product undesirable unnecessary. This may account limitation applications reactions more common general uses. Thus, development removable or functionalizable desirable. Another key problem resulting M-C bond be low, which limit scope coupling partners hence reaction patterns activation reactions. While Cp*Rh(III)-catalyzed arenes was reported only 7 years ago, significant progress been made this area past few years. We began our studies 2010, we others have demonstrated diversified catalytic realized using Cp*Rh(III) complexes with high reactivity, stability, compatibility. Account describes efforts solve some these challenges Rh(III) catalysis. fulfilled design arene substrates by taking advantage nucleophilicity, electrophilicity, oxidizing potential, properties participating ligand when coupled relatively reactive unsaturated as alkenes alkynes. These situ funtionalizable roles DG allowed extensive chemical manipulation initial product, especially diverse array heterocycles. In polar partners, Rh(III)-C(aryl) showed higher both an organometallic reagent nucleophilic aryl source. were accordingly activated virtue umpolung, ring strain, rearomatization. All possible integration compatibility Rh(III)-C into systems. date achieved under rhodium addition, means stoichiometric reactions, gained mechanistic insights interactions between Rh-C opened avenues future

Language: Английский

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Chiral Cyclopentadienyls: Enabling Ligands for Asymmetric Rh(III)-Catalyzed C–H Functionalizations

Accounts of Chemical Research, Journal Year: 2015, Volume and Issue: 48(5), P. 1308 - 1318

Published: April 17, 2015

ConspectusTransition-metal catalyzed C–H functionalizations became a complementary and efficient bond-forming strategy over the past decade. In this respect, Cp*Rh(III) complexes have emerged as powerful catalysts for broad spectrum of reactions giving access to synthetically versatile building blocks. Despite their high potential, corresponding catalytic enantioselective transformations largely lag behind. The targeted require all remaining three coordination sites central rhodium atom catalyst. consequence, chiral information on competent catalyst can only by stored in cyclopentadienyl unit. lack suitable enabling (Cpx) ligands is key hurdle preventing development such asymmetric versions. an set Cpx useable with variety different transition-metals unlock substantial application potential. This Account provides description our developments two classes C2-symmetric derivatives. We introduced side- back-wall concept enforce chirality transfer onto metal atom. first generation consists fused cyclohexane unit having pseudo axial methyl groups selectors rigidifying acetal moiety. second ligand derives from atrop-chiral biaryl-backbone which possesses adjustable substituents at its 3,3′-positions. Both families be modulated respective steric bulk adjust specific needs application. cyclopentadienes metalated under standard conditions. rhodium(I) ethylene are relatively air moisture represent storable stable precatalysts Rh(III)-catalyzed functionalizations. These then conveniently oxidized situ dibenzoyl peroxide give reactive CpxRh(III)(OBz)2 species. For instance, used directed activations aryl hydroxamates subsequent trapping olefins, providing dihydroisoquinolones very enantioselectivities. addition, we established highly selective intramolecular tethered higher substituted alkenes dihydrobenzofurans quaternary stereogenic centers. Concerning intermolecular reactions, allene coupling partners allow hydroarylation yielding allylated compounds. A process cyclometalated intermediate diazo reactants enables construction isoindolinones. Moreover, atropchiral biaryl motives using dehydrogenative Heck-type reaction. flexibly described showcasing applicability Rh(III) functionalization reactions. derivatives hold promise steering further catalysis.

Language: Английский

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Electrocatalytic C–H Activation

ACS Catalysis, Journal Year: 2018, Volume and Issue: 8(8), P. 7086 - 7103

Published: June 18, 2018

C–H activation has emerged as a transformative tool in molecular synthesis, but until recently oxidative activations have largely involved the use of stoichiometric amounts expensive and toxic metal oxidants, compromising overall sustainable nature chemistry. In sharp contrast, electrochemical been identified more efficient strategy that exploits storable electricity place byproduct-generating chemical reagents. Thus, transition-metal catalysts were shown to enable versatile reactions manner. While palladium catalysis set stage for C(sp2)–H C(sp3)–H functionalizations by N-containing directing groups, rhodium ruthenium allowed weakly coordinating amides acids. contrast these precious 4d transition metals, recent year witnessed emergence cobalt oxygenations, nitrogenations, C–C-forming [4+2] alkyne annulations. Thereby, silver(I) oxidants was prevented, improving environmentally benign catalysis. Herein, we summarize major advances organometallic otherwise inert bonds electrocatalysis through May 2018.

Language: Английский

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Co(III)-Catalyzed C–H Activation/Formal S_N-Type Reactions: Selective and Efficient Cyanation, Halogenation, and Allylation

Journal of the American Chemical Society, Journal Year: 2014, Volume and Issue: 136(51), P. 17722 - 17725

Published: Dec. 4, 2014

The first cobalt-catalyzed cyanation, halogenation, and allylation via C–H activation have been realized. These formal SN-type reactions generate valuable (hetero)aryl/alkenyl nitriles, iodides, bromides as well allylated indoles using a bench-stable Co(III) catalyst. High regio- mono-selectivity were achieved for these reactions. Additionally, proceeded efficiently with turnover number of 2200 at room temperature, which is unprecedented this Alkenyl substrates amides successfully utilized in Cp*Co(III)-catalyzed the time.

Language: Английский

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C−H Functionalisation for Hydrogen Isotope Exchange

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 57(12), P. 3022 - 3047

Published: Oct. 12, 2017

The various applications of hydrogen isotopes (deuterium, D, and tritium, T) in the physical life sciences demand a range methods for their installation an array molecular architectures. In this Review, we describe recent advances synthetic C-H functionalisation isotope exchange.

Language: Английский

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(Pentamethylcyclopentadienyl)cobalt(III)‐Catalyzed C–H Bond Functionalization: From Discovery to Unique Reactivity and Selectivity

Advanced Synthesis & Catalysis, Journal Year: 2017, Volume and Issue: 359(8), P. 1245 - 1262

Published: March 16, 2017

Abstract High‐valent (pentamethylcyclopentadienyl)cobalt(III) [Cp*Co(III)] catalysts were found as inexpensive alternatives to (pentamethylcyclopentadienyl)rhodium(III) [Cp*Rh(III)] in the field of C—H bond functionalization, and applied a variety transformations. In this review, after discovery early examples Cp*Co(III)‐catalyzed functionalization are summarized, unique reactivity selectivity Cp*Co(III) differences between cobalt rhodium catalysis intensively discussed. Such assumed be caused by lower electronegativity, hard nature, smaller ionic radius cobalt. magnified image

Language: Английский

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Mechanistic Studies on the Rh(III)-Mediated Amido Transfer Process Leading to Robust C–H Amination with a New Type of Amidating Reagent

Journal of the American Chemical Society, Journal Year: 2015, Volume and Issue: 137(13), P. 4534 - 4542

Published: March 20, 2015

Mechanistic investigations on the Cp*Rh(III)-catalyzed direct C-H amination reaction led us to reveal new utility of 1,4,2-dioxazol-5-one and its derivatives as highly efficient amino sources. Stepwise analysis C-N bond-forming process showed that competitive binding rhodium metal center amidating reagent or substrate is closely related efficiency. In this line, 1,4,2-dioxazol-5-ones were observed have a strong affinity cationic Rh(III) giving rise dramatically improved amidation efficiency when compared azides. Kinetics computational studies suggested high reactivity can also be attributed low activation energy an imido-insertion in addition coordination ability. While characterization Cp*Rh(III) complex bearing was achieved, facile conversion amido-inserted rhodacycle allowed for clear picture process. The newly developed applicable broad range substrates with functional group tolerance, releasing carbon dioxide single byproduct. Additional attractive features source, such they are more convenient prepare, store, use corresponding azides, take step closer toward ideal protocol.

Language: Английский

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