3d Transition Metals for C–H Activation

Chemical Reviews, Journal Year: 2018, Volume and Issue: 119(4), P. 2192 - 2452

Published: Nov. 27, 2018

C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these functionalizations required precious 4d or 5d transition metal catalysts. Given cost-effective sustainable nature earth-abundant first row metals, development less toxic, inexpensive 3d catalysts gained considerable recent momentum a significantly more environmentally-benign economically-attractive alternative. Herein, we provide comprehensive overview on until summer 2018.

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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Metalla-electrocatalyzed C–H Activation by Earth-Abundant 3d Metals and Beyond

Accounts of Chemical Research, Journal Year: 2019, Volume and Issue: 53(1), P. 84 - 104

Published: Dec. 19, 2019

To improve the efficacy of molecular syntheses, researchers wish to capitalize upon selective modification otherwise inert C-H bonds. The past two decades have witnessed considerable advances in coordination chemistry that set stage for transformative tools functionalizations. Particularly, oxidative C-H/C-H and C-H/Het-H transformations gained major attention because they avoid all elements substrate prefunctionalization. Despite advances, activations been dominated by precious transition metal catalysts based on palladium, ruthenium, iridium, rhodium, thus compromising sustainable nature overall activation approach. same holds true predominant use stoichiometric chemical oxidants regeneration active catalyst, prominently featuring hypervalent iodine(III), copper(II), silver(I) oxidants. Thereby, quantities undesired byproducts are generated, which preventive applications scale. In contrast, elegant merger homogeneous metal-catalyzed with electrosynthesis bears unique power achieve outstanding levels oxidant resource economy. Thus, contrast classical electrosyntheses control, metalla-electrocatalysis huge largely untapped potential unmet site selectivities means catalyst control. While indirect electrolysis using palladium complexes has realized, less toxic expensive base feature distinct beneficial assets toward this Account, I summarize emergence electrocatalyzed earth-abundant 3d metals beyond, a topical focus contributions from our laboratories through November 2019. cobalt electrocatalysis was identified as particularly powerful platform wealth transformations, including oxygenations nitrogenations well alkynes, alkenes, allenes, isocyanides, carbon monoxide, among others. As complementary tools, nickel, copper, very recently iron devised metalla-electrocatalyzed activations. Key success were detailed mechanistic insights, oxidation-induced reductive elimination scenarios. Likewise, development methods make weak O-coordination benefited crucial insights into catalyst's modes action experiment, operando spectroscopy, computation. Overall, thereby syntheses These electrooxidative frequently characterized improved chemoselectivities. Hence, ability dial redox at minimum level required desired transformation renders an ideal functionalization structurally complex molecules sensitive functional groups. This strategy was, inter alia, successfully applied scale-up continuous flow step-economical assembly polycyclic aromatic hydrocarbons.

Language: Английский

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Enantioselective C−H Activation with Earth‐Abundant 3d Transition Metals

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(37), P. 12803 - 12818

Published: May 11, 2019

Molecular syntheses largely rely on time- and labour-intensive prefunctionalization strategies. In contrast, C-H activation represents an increasingly powerful approach that avoids lengthy of prefunctionalized substrates, with great potential for drug discovery, the pharmaceutical industry, material sciences, crop protection, among others. The enantioselective functionalization omnipresent bonds has emerged as a transformative tool step- atom-economical generation chiral molecular complexity. However, this rapidly growing research area remains dominated by noble transition metals, prominently featuring toxic palladium, iridium rhodium catalysts. Indeed, despite significant achievements, use inexpensive sustainable 3d metals in asymmetric activations is still clearly its infancy. Herein, we discuss remarkable recent progress transformations via organometallic base up to April 2019.

Language: Английский

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Enantioselective C(sp³)–H Amidation of Thioamides Catalyzed by a Cobalt^III/Chiral Carboxylic Acid Hybrid System

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 58(4), P. 1153 - 1157

Published: Nov. 27, 2018

Abstract Recent advances in Cp x M III catalysis (M=Co, Rh, Ir) have enabled a variety of enantioselective C(sp 2 )−H functionalization reactions, but 3 is still largely unexplored. We describe an asymmetric amidation thioamides using achiral Co /chiral carboxylic acid hybrid catalytic system, which provides easy and straightforward access to chiral β‐amino thiocarbonyl carbonyl building blocks with quaternary carbon stereocenter.

Language: Английский

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Metal-catalyzed regiodivergent organic reactions

Chemical Society Reviews, Journal Year: 2019, Volume and Issue: 48(16), P. 4515 - 4618

Published: Jan. 1, 2019

Metal-catalyzed regiodivergent reactions allow control over regioselectivity in the synthesis of a wide range organic products. Starting from same material, it is possible to prepare different regioisomers just by appropriately choosing catalyst or modifying reaction conditions. Therefore, these methodologies should be included as key factor concept efficiency and atom economy synthetic chemistry. The potential this subject has been demonstrated mainly addition unsaturated carbon-carbon bonds, allylic propargylic nucleophilic substitutions, C-H activation reactions, cross-couplings, intramolecular intermolecular cyclizations. This review article overviews development rationalization regiodivergence fundamental last 15 years.

Language: Английский

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Electrochemical C−H Amination by Cobalt Catalysis in a Renewable Solvent

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(18), P. 5090 - 5094

Published: March 6, 2018

Syntheses of substituted anilines primarily rely on palladium-catalyzed coupling chemistry with prefunctionalized aryl electrophiles. While oxidative aminations have emerged as powerful alternatives, they largely produce undesired metal-containing by-products in stoichiometric quantities. In contrast, described herein is the unprecedented electrochemical C-H amination by cobalt-catalyzed activation. The environmentally benign electrocatalysis avoids metal oxidants, can be conducted under ambient air, and employs a biomass-derived, renewable solvent for sustainable an atom- step-economical manner H2 sole byproduct.

Language: Английский

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Electrochemical C−H/N−H Activation by Water‐Tolerant Cobalt Catalysis at Room Temperature

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(9), P. 2383 - 2387

Published: Jan. 10, 2018

Electrochemistry enabled C-H/N-H functionalizations at room temperature by external oxidant-free cobalt catalysis. Thus, the sustainable electrocatalysis manifold proceeds with excellent levels of chemoselectivity and positional selectivity, ample scope, thus allowing electrochemical C-H activation under exceedingly mild reaction conditions in water.

Language: Английский

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Electroremovable Traceless Hydrazides for Cobalt-Catalyzed Electro-Oxidative C–H/N–H Activation with Internal Alkynes

Journal of the American Chemical Society, Journal Year: 2018, Volume and Issue: 140(25), P. 7913 - 7921

Published: May 29, 2018

Electrochemical oxidative C–H/N–H activations have been accomplished with a versatile cobalt catalyst in terms of [4 + 2] annulations internal alkynes. The electro-oxidative C–H activation manifold proved viable an undivided cell setup under exceedingly mild reaction conditions at room temperature using earth-abundant catalysts. electrochemical catalysis prevents the use transition metal oxidants catalysis, generating H2 as sole byproduct. Detailed mechanistic studies provided strong support for facile cobaltation by initially formed cobalt(III) catalyst. subsequent alkyne migratory insertion was interrogated mass spectrometry and DFT calculations, providing formation key seven-membered cobalta(III) cycle regioselective fashion. Key to success unprecedented alkynes represented N-2-pyridylhydrazides, which we developed traceless electrocleavage strategy electroreductive samarium temperature.

Language: Английский

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Enantioselective C H Bond Functionalizations by 3d Transition-Metal Catalysts

Trends in Chemistry, Journal Year: 2019, Volume and Issue: 1(5), P. 471 - 484

Published: April 20, 2019

Language: Английский

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