3d Transition Metals for C–H Activation

Chemical Reviews, Год журнала: 2018, Номер 119(4), С. 2192 - 2452

Опубликована: Ноя. 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.

Язык: Английский

---

Electrocatalytic C–H Activation

ACS Catalysis, Год журнала: 2018, Номер 8(8), С. 7086 - 7103

Опубликована: Июнь 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.

Язык: Английский

---

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

Angewandte Chemie International Edition, Год журнала: 2018, Номер 57(18), С. 5090 - 5094

Опубликована: Март 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.

Язык: Английский

---

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

Journal of the American Chemical Society, Год журнала: 2018, Номер 140(25), С. 7913 - 7921

Опубликована: Май 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.

Язык: Английский

---

Weak-Coordination in C–H Bond Functionalizations Catalyzed by 3d Metals

ACS Catalysis, Год журнала: 2022, Номер 12(6), С. 3452 - 3506

Опубликована: Март 3, 2022

Transition-metal-catalyzed C–H bond functionalizations have had an enormous influence on organic synthesis in recent times. However, the use of low-abundance 4d and 5d metals is almost inevitable, they are high demand. This will be a cause concern, hence, it important to develop methods based 3d metals, which widely present Earth's crust. In this regard, metal catalysts or their precursors for catalysis, general, functionalizations, particular, has gained significant momentum The major development catalytic with been achieved predominantly strongly coordinating directing groups such as pyridyl, pyrimidinyl, pyrazolyl, 8-amino-quinolinyl groups. Thus, prefunctionalization substrates these necessary, contradicts step- atom-economy activation. commonly available functional aldehyde, ketone, carboxylic acid, amide, hydroxy, N-oxides loosely bind through weak-coordination. These weakly orient activate regioselectively without need preinstalled Although challenging, contemporary topic actively pursued by many researchers Through article, we provide comprehensive overview metal-catalyzed, coordinating, directing-group-enabled reported until March 2021.

Язык: Английский

---

Electrochemical Cobalt‐Catalyzed C−H Activation

Chemistry - A European Journal, Год журнала: 2018, Номер 24(61), С. 16209 - 16217

Опубликована: Июнь 19, 2018

Carbon-heteroatom bonds represent omnipresent structural motifs of the vast majority functionalized materials and bioactive compounds. C-H activation has emerged as arguably most efficient strategy to construct C-Het bonds. Despite major advances, these transformations were largely dominated by precious transition metal catalysts, in combination with stoichiometric, toxic oxidants. Herein, we discuss recent evolution cobalt-catalyzed activations that enable formations electricity sole sustainable oxidant until May 2018.

Язык: Английский

---

Cp*M-Catalyzed Direct Annulation with Terminal Alkynes and Their Surrogates for the Construction of Multi-Ring Systems

ACS Catalysis, Год журнала: 2020, Номер 10(17), С. 9747 - 9757

Опубликована: Авг. 3, 2020

Transition-metal-catalyzed C–H activation followed by oxidative cyclization with unsaturated coupling partners has been a valuable synthetic tool for the multiring molecular scaffolds. This Perspective introduces recent progress on Cp*M-catalyzed (M = Co, Rh, and Ir) direct annulation of functionalized arenes terminal alkynes their equivalents through bond cleavage. The highlighted examples are categorized according to 10 different types reagents used in transformations. representative conditions, selected reaction scope, key mechanistic aspects briefly summarized.

Язык: Английский

---

Recent advances in cobalt-catalysed C–H functionalizations

Organic & Biomolecular Chemistry, Год журнала: 2019, Номер 17(48), С. 10119 - 10141

Опубликована: Янв. 1, 2019

Ready availability, low cost and toxicity of cobalt salts have redirected the attention researchers away from noble metals, such as Pd, Rh, Ir, towards Co in field C-H functionalization. In this context, examples Co-catalysed functionalization exponentially grown over last few decades. This present review focuses on most recent developments C(sp2)-H C(sp3)-H functionalizations. Included is also a comprehensive overview enantioselective transformations.

Язык: Английский

---

Room-Temperature C–H Bond Functionalization by Merging Cobalt and Photoredox Catalysis

ACS Catalysis, Год журнала: 2018, Номер 8(9), С. 8115 - 8120

Опубликована: Июль 17, 2018

A non-noble metal-free protocol has been developed for C–H bond functionalization at room temperature by merging cobalt-mediated catalysis with photocatalysis. The reaction requires only oxygen as sole oxidant and operated under redox-neutral conditions. Visible-light activated photoredox catalyst functions an electron transfer reagent a terminal in the N–H annulation. methodology allows annulations various coupling partners. concept demonstrated herein is expected to enhance scope of cobalt applied sustainable fine chemical synthesis.

Язык: Английский

---

Concise Synthesis of Isocoumarins through Rh-Catalyzed Direct Vinylene Annulation: Scope and Mechanistic Insight

Organic Letters, Год журнала: 2020, Номер 22(14), С. 5706 - 5711

Опубликована: Июль 8, 2020

Transition-metal-catalyzed activation of inert C-H bonds and subsequent C-C bond formation have emerged as powerful synthetic tools for the synthesis elaborate cyclic molecules. In this report, we introduce an efficient method 3,4-unsubstituted isocoumarins adopting electron-deficient CpERh complex catalyst. The use vinylene carbonate a transfer reagent enables direct construction from readily available benzoic acids, without any external oxidants well bases. reaction mechanism is evaluated by computational analysis to find unprecedented "rhodium shift" event within catalytic cycle.

Язык: Английский

---