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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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 C–N Bond Forming Reactions Using Organic Azides as the Nitrogen Source: A Journey for the Mild and Versatile C–H Amination

Accounts of Chemical Research, Journal Year: 2015, Volume and Issue: 48(4), P. 1040 - 1052

Published: March 30, 2015

Owing to the prevalence of nitrogen-containing compounds in functional materials, natural products and important pharmaceutical agents, chemists have actively searched for development efficient selective methodologies allowing facile construction carbon-nitrogen bonds. While metal-catalyzed C-N cross-coupling reactions been established as one most general protocols bond formation, these methods require starting materials equipped with groups such (hetero)aryl halides or their equivalents, thus generating stoichiometric amounts halide salts byproducts. To address this aspect, a transition-metal-catalyzed direct C-H amination approach has emerged step- atom-economical alternative conventional reactions. However, despite significant recent advances metal-mediated reactions, available procedures need harsh conditions requiring external oxidants. In context, we were curious see whether mild protocol could be achieved using organic azides amino source. We envisaged that dual role an environmentally benign source also internal oxidant via N-N2 cleavage would key develop employing azides. An additional advantage was anticipated: sole byproduct is molecular nitrogen (N2) under perspective catalytic conditions. This Account mainly describes our research efforts on rhodium- iridium-catalyzed Under initially optimized Rh(III)-catalyzed conditions, not only sulfonyl but aryl- alkyl utilized sources reaction various types C(sp(2))-H bonds bearing directing pyridine, amide, ketoxime. More recently, new catalyst system Ir(III) species developed amidation arenes alkenes acyl exceptionally As extension, primary C(sp(3))-H realized basis superior activity Cp*Ir(III) catalyst. Mechanistic investigations revealed cycle operated three stages: (i) chelation-assisted metallacycle formation cleavage; (ii) through situ generation metal-nitrenoid intermediate followed by insertion imido moiety metal carbon bond; (iii) product release protodemetalation concomitant regeneration. addition, summarizes ruthenium- cobalt-catalyzed azides, own other groups. Comparative studies relative performance those systems are briefly described.

Language: Английский

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Direct Photocatalyzed Hydrogen Atom Transfer (HAT) for Aliphatic C–H Bonds Elaboration

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 1875 - 1924

Published: Aug. 6, 2021

Direct photocatalyzed hydrogen atom transfer (d-HAT) can be considered a method of choice for the elaboration aliphatic C–H bonds. In this manifold, photocatalyst (PCHAT) exploits energy photon to trigger homolytic cleavage such bonds in organic compounds. Selective bond may achieved by judicious abstractor (key parameters are electronic character and molecular structure), as well reaction additives. Different classes PCsHAT available, including aromatic ketones, xanthene dyes (Eosin Y), polyoxometalates, uranyl salts, metal-oxo porphyrin tris(amino)cyclopropenium radical dication. The processes (mainly C–C formation) most cases carried out under mild conditions with help visible light. aim review is offer comprehensive survey synthetic applications d-HAT.

Language: Английский

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Weakly Coordinating Directing Groups for Ruthenium(II)‐ Catalyzed CH Activation

Advanced Synthesis & Catalysis, Journal Year: 2014, Volume and Issue: 356(7), P. 1461 - 1479

Published: April 30, 2014

Abstract Synthetically useful functional groups, including ketones, amides, carbamates, carboxylic acids, aldehydes or ethers, have been identified as weakly coordinating directing groups in efficient ruthenium(II)‐catalyzed CH functionalizations. This strategy set the stage for versatile bond olefinations, oxygenations, nitrogenations and oxidative alkyne annulations among others. Thereby, step‐economical access to diversely decorated arenes heteroarenes was provided a sustainable fashion. magnified image

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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Manganese-Catalyzed C–H Activation

ACS Catalysis, Journal Year: 2016, Volume and Issue: 6(6), P. 3743 - 3752

Published: April 27, 2016

Manganese is found in the active center of numerous enzymes that operate by an outer-sphere homolytic C–H cleavage. Thus, a plethora bioinspired radical-based functionalizations manganese catalysis have been devised during past decades. In contrast, organometallic activation means has emerged only recently as increasingly viable tool organic synthesis. These manganese(I)-catalyzed processes enabled variety with ample scope, which very set stage for substitutive functionalizations. The versatile largely operates isohypsic, thus redox-neutral, mode action through chelation assistance, and provided step-economical access to structurally divers compounds relevance inter alia bioorganic, agrochemical, medicinal chemistry well material sciences.

Language: Английский

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Recent advances in directed C–H functionalizations using monodentate nitrogen-based directing groups

Organic Chemistry Frontiers, Journal Year: 2014, Volume and Issue: 1(7), P. 843 - 843

Published: May 14, 2014

The use of directing groups has proven to be a successful strategy enhance reactivity and control selectivity in C–H functionalization reactions. In the past decade, multitude new transformations have been explored, several recent reviews discussed group approaches for functionalization. This review focuses specifically on monodentate nitrogen-based published during two years, with aim covering body literature that is complementary existing reviews.

Language: Английский

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C–H activation

Nature Reviews Methods Primers, Journal Year: 2021, Volume and Issue: 1(1)

Published: June 17, 2021

Language: Английский

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Recent advances in positional-selective alkenylations: removable guidance for twofold C–H activation

Organic Chemistry Frontiers, Journal Year: 2017, Volume and Issue: 4(7), P. 1435 - 1467

Published: Jan. 1, 2017

Recent advances in transition-metal catalyzed positional-selective alkenylations via twofold C–H activation directed by removable or traceless directing groups are reviewed.

Language: Английский

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