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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(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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Full Selectivity Control in Cobalt(III)‐Catalyzed C−H Alkylations by Switching of the C−H Activation Mechanism

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(35), P. 10378 - 10382

Published: June 21, 2017

Selectivity control in hydroarylation-based C-H alkylation has been dominated by steric interactions. A conceptually distinct strategy that exploits the programmed switch activation mechanism means of cobalt catalysis is presented, which sets stage for convenient alkylations with unactivated alkenes. Detailed mechanistic studies provide compelling evidence a programmable from linear-selective ligand-to-ligand hydrogen transfer to branched-selective base-assisted internal electrophilic-type substitution.

Language: Английский

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C–H functionalization by high-valent Cp*Co(iii) catalysis

Chemical Communications, Journal Year: 2017, Volume and Issue: 53(22), P. 3165 - 3180

Published: Jan. 1, 2017

Significant progress has been accomplished in directed C–H functionalization through the use of earth-abundant and inexpensive first-row transition metals.

Language: Английский

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Cobalt‐Catalyzed C−H Thiolation through Dehydrogenative Cross‐Coupling

Angewandte Chemie International Edition, Journal Year: 2016, Volume and Issue: 55(37), P. 11287 - 11291

Published: July 20, 2016

Abstract A cobalt‐catalyzed dehydrogenative cross‐coupling of thiols and indoles is reported. Using a cooperative reaction system, new mode action for the C−heteroatom bond formation was found. The directed C−H activation catalysis overrides an undirected thiolation indole in 3‐position that occurs absence cobalt. Mechanistic studies indicate sequence activation, thiolate transfer, reductive elimination.

Language: Английский

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Direct Functionalization of C−H Bonds by Iron, Nickel, and Cobalt Catalysis

Chemistry - A European Journal, Journal Year: 2017, Volume and Issue: 23(39), P. 9206 - 9232

Published: June 7, 2017

Abstract Non‐precious‐metal‐catalyzed reactions are of increasing importance in chemistry due to the outstanding ecological and economic properties these metals. In subfield metal‐catalyzed direct C−H functionalization reactions, recent years have shown an number publications dedicated this topic. Nickel, cobalt, last but not least iron, started enter a field which was long dominated by precious metals such as palladium, rhodium, ruthenium, iridium. The present review article summarizes development iron‐, nickel‐, cobalt‐catalyzed until end 2016, discusses scope limitations transformations.

Language: Английский

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Unnatural Amino Acid Synthesis Enabled by the Regioselective Cobalt(III)‐Catalyzed Intermolecular Carboamination of Alkenes

Angewandte Chemie International Edition, Journal Year: 2016, Volume and Issue: 55(48), P. 15166 - 15170

Published: Oct. 27, 2016

Abstract Herein, we report an unprecedented regioselective and entirely atom‐economic cobalt(III)‐catalyzed method for the non‐annulative, intermolecular carboamination of alkenes. The methodology enables direct synthesis unnatural amino acid derivatives proceeds under redox‐neutral conditions with a completely C−C bond C−N formation. Furthermore, this reaction exemplifies inherently different mechanistic behavior Cp*Co III catalyst its Cp*Rh counterpart, especially towards β‐H‐elimination.

Language: Английский

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Mild C−H/C−C Activation by Z‐Selective Cobalt Catalysis

Angewandte Chemie International Edition, Journal Year: 2016, Volume and Issue: 55(26), P. 7408 - 7412

Published: May 4, 2016

Abstract Cationic cobalt complexes enable unprecedented cobalt‐catalyzed C−H/C−C functionalizations with unique selectivity features. The versatile catalyst proved broadly applicable, enabled efficient cleavage at room temperature, and delivered Z‐alkenes excellent diastereocontrol.

Language: Английский

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An Organic Chemist’s Guide to N-Nitrosamines: Their Structure, Reactivity, and Role as Contaminants

The Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 86(3), P. 2037 - 2057

Published: Jan. 21, 2021

N-Nitrosamines are a class of compounds notorious both for the potent carcinogenicity many its members and their widespread occurrence throughout human environment, from air water to our diets drugs. Considerable effort has been dedicated understanding N-nitrosamines as contaminants, methods prevention, remediation, detection ongoing challenges. Understanding chemistry will be key addressing these To facilitate such understanding, we focus in this Perspective on structure, reactivity, synthetic applications with an emphasis alkyl N-nitrosamines. The role contaminants also discussed.

Language: Английский

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Highly Stereoselective Cobalt(III)‐Catalyzed Three‐Component C−H Bond Addition Cascade

Angewandte Chemie International Edition, Journal Year: 2016, Volume and Issue: 55(41), P. 12650 - 12654

Published: June 15, 2016

Abstract A highly stereoselective three‐component C(sp 2 )−H bond addition across alkene and polarized π‐bonds is reported for which Co III catalysis was shown to be much more effective than Rh . The reaction proceeds at ambient temperature with both aryl alkyl enones employed as efficient coupling partners. Moreover, the exhibits extremely broad scope respect aldehyde input; electron rich poor aromatic, alkenyl, branched unbranched aldehydes all couple in good yield high diastereoselectivity. Multiple directing groups participate this transformation, including pyrazole, pyridine, imine functional groups. Both aromatic alkenyl bonds undergo cascade, product can readily converted into diastereomerically pure five‐membered lactones. Additionally, first asymmetric reactions ‐catalyzed C−H functionalization are demonstrated cascades employing N‐tert ‐butanesulfinyl imines. These examples represent transition metal catalyzed additions imines, versatile extensively used intermediates synthesis of amines.

Language: Английский

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