The Essential Role of Bond Energetics in C–H Activation/Functionalization

Chemical Reviews, Год журнала: 2017, Номер 117(13), С. 8622 - 8648

Опубликована: Март 10, 2017

The most fundamental concepts in chemistry are structure, energetics, reactivity and their inter-relationships, which indispensable for promoting into a rational science. In this regard, bond energy, the intrinsic determinant directly related to structure reactivity, should be essential serving as quantitative basis design understanding of organic transformations. Although C-H activation/functionalization have drawn tremendous research attention flourished during past decades, governing rules energetics these processes is still fragmentary seems applicable only limited cases, such metal-oxo-mediated hydrogen atom abstraction. Despite complexity difficulties measuring energies both substrates intermediates, definitely very important issue that more generally contemplated. To end, review rooted energetic aspects activation/functionalization, were previously rarely discussed detail. Starting with concise but necessary introduction various classical methods heterolytic homolytic bonds, present provides examples applied concept values energy rationalizing observations associated and/or selectivity activation/functionalization.

Язык: Английский

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Alkenylation of Arenes and Heteroarenes with Alkynes

Chemical Reviews, Год журнала: 2016, Номер 116(10), С. 5894 - 5986

Опубликована: Апрель 25, 2016

This review is focused on the analysis of current data new methods alkenylation arenes and heteroarenes with alkynes by transition metal catalyzed reactions, Bronsted/Lewis acid promoted transformations, others. The synthetic potential, scope, limitations, mechanistic problems reactions are discussed. insertion an alkenyl group into aromatic heteroaromatic rings inter- or intramolecular ways provides a route to derivatives styrene, stilbene, chalcone, cinnamic acid, various fused carbo- heterocycles, etc.

Язык: Английский

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Rh(III)- and Ir(III)-Catalyzed C–H Alkynylation of Arenes under Chelation Assistance

Journal of the American Chemical Society, Год журнала: 2014, Номер 136(12), С. 4780 - 4787

Опубликована: Март 4, 2014

An efficient Rh(III)- and Ir(III)-catalyzed, chelation-assisted C–H alkynylation of a broad scope (hetero)arenes has been developed using hypervalent iodine-alkyne reagents. Heterocycles, N-methoxy imines, azomethine secondary carboxamides, azo compounds, N-nitrosoamines, nitrones are viable directing groups to entail ortho alkynylation. The reaction proceeded under mild conditions with controllable mono- dialkynylation selectivity when both was observed. Rh(III) Ir(III) catalysts exhibited complementary substrate in this reaction. synthetic applications the coupled products have demonstrated subsequent derivatization reactions. Some mechanistic studies conducted, two complexes established as key intermediates. current system complements those previously reported gold or palladium catalysis iodine

Язык: Английский

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Merging Visible Light Photoredox Catalysis with Metal Catalyzed C–H Activations: On the Role of Oxygen and Superoxide Ions as Oxidants

Accounts of Chemical Research, Год журнала: 2016, Номер 49(9), С. 1969 - 1979

Опубликована: Авг. 24, 2016

The development of efficient catalytic systems for direct aromatic C-H bond functionalization is a long-desired goal chemists, because these protocols provide environmental friendly and waste-reducing alternatives to classical methodologies C-C C-heteroatom formation. A key challenge transformations the reoxidation in situ generated metal hydride or low-valent complexes primary forming cycle. To complete cycle regenerate activation catalyst, (super)stoichiometric amounts Cu(II) Ag(I) salts have often been applied. Recently, "greener" approaches developed by applying molecular oxygen combination with salts, internal oxidants that are cleaved during reaction, solvents additives enabling reoxidation. All improved friendliness but not overcome obstacles associated overall limited functional group substrate tolerance. Hence, processes do feature unfavorable aspects described above products streamlined as well economically ecologically advantageous manner would be desirable. In this context, we decided examine visible light photoredox catalysis new alternative conventionally applied regeneration/oxidation procedures. This Account summarizes our recent advances expanding area will highlight concept merging distinct redox functionalizations through application catalysis. Photoredox can considered electron-donating -accepting processes, making use visible-light absorbing homogeneous heterogeneous metal-based catalysts, organic dye sensitizers polymers. As consequence, is, principle, an ideal tool recycling any given catalyst via coupled electron transfer (ET) process. Here describe first successful endeavors address challenges combining different ruthenium, rhodium, palladium catalyzed activations. Since only small oxidant immediately consumed transformations, side reactions substrates avoided. Thus, usually oxidant-sensible used, which makes methods highly suitable complex structure syntheses. Moreover, mechanistic studies shed on reaction pathways, intermediates, species. dual concept, consisting combined functionalization, provides many opportunities further explorations field functionalization.

Язык: Английский

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Toolbox for Distal C–H Bond Functionalizations in Organic Molecules

Chemical Reviews, Год журнала: 2021, Номер 122(6), С. 5682 - 5841

Опубликована: Окт. 18, 2021

Transition-metal-catalyzed C–H activation has developed a contemporary approach to the omnipresent area of retrosynthetic disconnection. Scientific researchers have been tempted take help this methodology plan their synthetic discourses. This paradigm shift helped in development industrial units as well, making synthesis natural products and pharmaceutical drugs step-economical. In vast zone bond activation, functionalization proximal bonds gained utmost popularity. Unlike bonds, distal is more strenuous requires distinctly specialized techniques. review, we compiled various methods adopted functionalize mechanistic insights within each these procedures, scope methodology. With give complete overview expeditious progress made field organic chemistry while also highlighting its pitfalls, thus leaving open for further modifications.

Язык: Английский

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