Understanding active species in catalytic transformations: From molecular catalysis to nanoparticles, leaching, “Cocktails” of catalysts and dynamic systems

Coordination Chemistry Reviews, Год журнала: 2017, Номер 346, С. 2 - 19

Опубликована: Янв. 7, 2017

Язык: Английский

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Photoinduced Nickel-Catalyzed Chemo- and Regioselective Hydroalkylation of Internal Alkynes with Ether and Amide α-Hetero C(sp³)–H Bonds

Journal of the American Chemical Society, Год журнала: 2017, Номер 139(38), С. 13579 - 13584

Опубликована: Сен. 1, 2017

A direct hydroalkylation of disubstituted alkynes with unfunctionalized ethers and amides was achieved in an atom-efficient additive-free manner through the synergistic combination photoredox nickel catalysis. The protocol effective a wide range internal alkynes, providing products highly selective fashion. Notably, observed regioselectivity is complementary to conventional radical addition processes. Mechanistic investigations suggest that photoexcited iridium catalyst facilitated activation via single-electron transfer.

Язык: Английский

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Site-Selective Alkenylation of δ-C(sp³)–H Bonds with Alkynes via a Six-Membered Palladacycle

Journal of the American Chemical Society, Год журнала: 2016, Номер 138(34), С. 10750 - 10753

Опубликована: Авг. 16, 2016

Most chelation-assisted aliphatic C-H activation proceeds through a kinetically favored five-membered cyclometalated intermediate. Here, we report the first site-selective alkenylation of δ-C(sp(3))-H in presence more accessible γ-C(sp(3))-H bonds via less six-membered palladacycle. A wide range functional groups are tolerated, and unique protocol can be applied to synthesis chiral piperidines. Moreover, mechanistic insights have been conducted elucidate origin unusual site-selectivity.

Язык: Английский

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Nitrogen Effects Endowed by Doping Electron-Withdrawing Nitrogen Atoms into Polycyclic Aromatic Hydrocarbon Fluorescence Emitters

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(23), С. 15977 - 15985

Опубликована: Май 7, 2024

Unveiling innovative mechanisms to design new highly efficient fluorescent materials and, thereby, fabricate high-performance organic light-emitting diodes (OLEDs) is a concerted endeavor in both academic and industrial circles. Polycyclic aromatic hydrocarbons (PAHs) have been widely used as emitters blue OLEDs, but device performances are far from satisfactory. In response, we propose the concept of "nitrogen effects" endowed by doping electron-withdrawing nitrogen atoms into PAH fluorescence emitters. The presence n orbital on imine conducive promoting electron coupling, which leads increased molar absorptivity an accelerated radiative decay rate emitters, thereby facilitating Förster energy transfer (FET) process OLEDs. Additionally, electronically withdrawing enhances host–guest interactions, positively affecting FET horizontal orientation factor emitting layer. To validate concept, cobalt-catalyzed multiple C–H annulation has utilized incorporate alkynes imine-based frameworks, enables various imine-embedded (IE-PAH) cyclization demonstrates notable regioselectivity, offering practical tool precisely introduce peripheral groups at desired positions with bulky alkyl units positioned adjacent atoms, were previously beyond reach through Friedel–Crafts reaction. Blue OLEDs fabricated IE-PAHs exhibit outstanding performance maximum external quantum efficiency (EQEmax) 32.7%. This achievement sets groundbreaking record for conventional PAH-based EQEmax 24.0%.

Язык: Английский

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Dirhodium-Catalyzed Asymmetric Transformations of Alkynes via Carbene Intermediates

Accounts of Chemical Research, Год журнала: 2025, Номер unknown

Опубликована: Янв. 31, 2025

ConspectusFunctionalization of alkynes is an established cornerstone organic synthesis. While numerous transition metals exhibit promising activities in the transformations via π-insertion or oxidative cyclometalation, Lewis π-acids offer a different approach. By coordinating with through π-bonding, facilitate nucleophilic addition, leading to formation alkenyl metal species. These species can undergo electron rearrangement generate carbenes, which are crucial intermediates for subsequent carbene transfer reactions. This reaction pathway provides versatile route alkyne functionalization, especially asymmetric manner. Although π-acid, gold(I), pioneered this mode, development variants remains challenging due linear coordination gold(I). Therefore, expanding range catalysts beyond gold(I) complexes other would further advances chiral molecule construction and exploration novel modes.In Account, we present concise review multifunctionalization dirhodium-catalyzed transformations, providing modulation strategies substrates plausible mechanisms. In aromatization-driven strategy, furanyl dirhodium generated from enynone, terminated by enantioselective intramolecular C-H insertion, cyclopropanation, aromatic substitution, Büchner reaction, giving dihydroindoles, dihydrobenzofurans, cyclopropane-fused tetrahydroquinolines, fluorenes, cyclohepta[b]benzofurans. The cap-tether strategy was developed study balance reactivity selectivity azo-enyne. gave first catalytic cycloisomerization azo-enyne, affording centrally axially isoindazole derivatives. synergistic activation i.e., EWG C-H···O interaction, introduced achieve enynes, cyclopropane-annulated bicyclic systems enynals. Benefiting these successes, difluoromethyl-substituted enynes were designed proven be effective substrates. With corresponding benzo-1,6-enynes as substrates, biscyclopropanation cascaded cyclopropanation/cyclopropenation achieved using dicarbene equivalents. Additionally, benzo-1,5-enynal vinyl carbene, reacted variety alkenes [2 + 1] cycloaddition, [4 3] formal allylation, spiro fused polycyclic heterocycles. Coupling desymmetrization, successfully diynals, constructing furan-fused dihydropiperidines alkyne-substituted aza-quaternary stereocenter. Notably, analyzing X-ray structures several dirhodium-alkyne π-complexes, together results DFT calculations control experiments, obtained evidence supporting making well-defined paddlewheel-like dirhodium(II) stand out among complexes. We anticipate that our research will significantly advance fields dirhodium, alkyne, chemistry.

Язык: Английский

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A lesson for site-selective C–H functionalization on 2-pyridones: radical, organometallic, directing group and steric controls

Chemical Science, Год журнала: 2017, Номер 9(1), С. 22 - 32

Опубликована: Ноя. 27, 2017

This minireview focuses on recent advances in site-selective C–H functionalization 2-pyridone which is an important heterocyclic motif medicinal and pharmaceutical chemistry.

Язык: Английский

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Recent Advances in the Chemistry of Pentafulvenes

Chemical Reviews, Год журнала: 2017, Номер 117(5), С. 3930 - 3989

Опубликована: Фев. 2, 2017

Pentafulvenes are a unique class of compounds that originally attracted attention due to their propensity display nonbenzenoid aromaticity. Subsequently, they were recognized as valuable synthons for the construction wide range by virtue ability multiple cycloaddition profiles. Naturally, this area organic chemistry has experienced rapid growth over last five decades, fueled elegant work showcasing reactivity pentafulvenes in plethora reactions. In Review, we have attempted provide systematic account methods generation pentafulvenes, rich and varied chemistry, organometallic reactions, theoretical studies support versatility. Further, highlighted applications synthesis variety complex structural frameworks. It is our conviction Review will be useful chemists, spur further research promising area.

Язык: Английский

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syn-Selective alkylarylation of terminal alkynes via the combination of photoredox and nickel catalysis

Nature Communications, Год журнала: 2018, Номер 9(1)

Опубликована: Окт. 25, 2018

Substituted alkenes are pivotal structural motifs found in pharmaceuticals and agrochemicals. Although numerous methods have been developed to construct substituted alkenes, a generally efficient, mild, catalytic platform for the conversion of alkynes this highly functionalized scaffold via successive C-C bond forming steps remains high demand. Here we describe an intermolecular, regio- syn-stereoselective alkylarylation terminal with tertiary alkyl oxalates photoredox-Ni dual catalysis. This protocol, synergistically combining Ir/Ni-catalyzed alkyne difunctionalization photoinduced alkene isomerization, affords trisubstituted excellent efficiency syn-stereoselectivity. The mild conditions tolerate many functional groups, allowing broad scope respect alkynes, aryl bromides, oxalates.

Язык: Английский

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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

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Catalyst‐Controlled Regiodivergent Alkyne Insertion in the Context of C−H Activation and Diels–Alder Reactions: Synthesis of Fused and Bridged Cycles

Angewandte Chemie International Edition, Год журнала: 2017, Номер 56(28), С. 8163 - 8167

Опубликована: Май 17, 2017

Abstract Rhodium(III)‐ and cobalt(III)‐catalyzed C−H activation of indoles coupling with 1,6‐enynes is discussed. Under rhodium(III) catalysis, the alkyne insertion follows 2,1‐regioselectivity a subsequent type‐I intramolecular Diels–Alder reaction (IMDA) to afford [6,5]‐fused cycles. When catalyzed by cobalt(III) congener, 1,2‐insertion preferred, followed rare type‐II IMDA, thus leading bridged [3,3,1]‐cycles. This selectivity was mainly tuned steric sensitivity catalyst.

Язык: Английский

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