Photocatalytic Late-Stage C–H Functionalization

Chemical Reviews, Год журнала: 2023, Номер 123(8), С. 4237 - 4352

Опубликована: Янв. 24, 2023

The emergence of modern photocatalysis, characterized by mildness and selectivity, has significantly spurred innovative late-stage C–H functionalization approaches that make use low energy photons as a controllable source. Compared to traditional strategies, photocatalysis paves the way toward complementary and/or previously unattainable regio- chemoselectivities. Merging compelling benefits with workflow offers potentially unmatched arsenal tackle drug development campaigns beyond. This Review highlights photocatalytic strategies small-molecule drugs, agrochemicals, natural products, classified according targeted bond newly formed one. Emphasis is devoted identifying, describing, comparing main mechanistic scenarios. draws critical comparison between established ionic chemistry photocatalyzed radical-based manifolds. aims establish current state-of-the-art illustrate key unsolved challenges be addressed in future. authors aim introduce general readership functionalization, specialist practitioners evaluation methodologies, potential for improvement, future uncharted directions.

Язык: Английский

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Ligand‐to‐Metal Charge Transfer (LMCT) Photochemistry at 3d‐Metal Complexes: An Emerging Tool for Sustainable Organic Synthesis

ChemCatChem, Год журнала: 2022, Номер 14(19)

Опубликована: Авг. 11, 2022

Abstract Despite the rich photochemistry of 3d‐metal complexes, utilization excited‐state reactivity these compounds in organic synthesis has been historically overlooked. The advent photoredox catalysis changed perception synthetic chemists towards photochemistry, and nowadays potential photoinduced, outer‐sphere single‐electron transfer events is widely recognized. More recently, an emerging new mode photoactivation taken spotlight, based on inner‐sphere triggered by population ligand‐to‐metal charge‐transfer (LMCT) excited states. Contrarily to photoredox, LMCT‐activation does not rely matching redox potentials, offers unique profiles particularly well suited Earth‐abundant metal complexes. Those appealing features are propelling development methods using this blueprint generate highly reactive open‐shell species under mild conditions. aim contribution provide a didactical tool for comprehension concept facilitate methodologies achieve sustainable chemical transformations.

Язык: Английский

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Supramolecular Coordination Cages for Artificial Photosynthesis and Synthetic Photocatalysis

Chemical Reviews, Год журнала: 2023, Номер 123(9), С. 5225 - 5261

Опубликована: Янв. 20, 2023

Because sunlight is the most abundant energy source on earth, it has huge potential for practical applications ranging from sustainable supply to light driven chemistry. From a chemical perspective, excited states generated by make thermodynamically uphill reactions possible, which forms basis storage into fuels. In addition, with light, open-shell species can be open up new reaction pathways in organic synthesis. Crucial are photosensitizers, absorb and transfer substrates various mechanisms, processes that highly depend distance between molecules involved. Supramolecular coordination cages well studied synthetically accessible vessels single cavities guest binding, ensuring close proximity of different components. Due high modularity their size, shape, nature metal centers ligands, ideal platforms exploit preorganization photocatalysis. Herein we focus application supramolecular photocatalysis artificial photosynthesis photo(redox) catalysis. Finally, brief overview immobilization strategies provides tools implementing devices. This review inspiration future design photocatalytic host-guest systems producing solar fuels complex molecules.

Язык: Английский

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Metallaphotoredox catalysis for sp³C–H functionalizations through hydrogen atom transfer (HAT)

Chemical Society Reviews, Год журнала: 2023, Номер 52(12), С. 4099 - 4120

Опубликована: Янв. 1, 2023

sp 3 C–H functionalizations under the combination of photocatalytic HAT and transition metal catalysis.

Язык: Английский

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Decarboxylative Borylation and Cross-Coupling of (Hetero)aryl Acids Enabled by Copper Charge Transfer Catalysis

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(14), С. 6163 - 6172

Опубликована: Апрель 4, 2022

We report a copper-catalyzed strategy for arylboronic ester synthesis that exploits photoinduced ligand-to-metal charge transfer (LMCT) to convert (hetero)aryl acids into aryl radicals amenable ambient-temperature borylation. This near-UV process occurs under mild conditions, requires no prefunctionalization of the native acid, and operates broadly across diverse aryl, heteroaryl, pharmaceutical substrates. also one-pot procedure decarboxylative cross-coupling merges catalytic LMCT borylation palladium-catalyzed Suzuki-Miyaura arylation, vinylation, or alkylation with organobromides access range value-added products. The utility these protocols is highlighted through development heteroselective double-decarboxylative C(sp2)-C(sp2) coupling sequence, pairing halogenation processes two distinct (including substrates) subsequent cross-coupling.

Язык: Английский

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Photochemistry Journey to Multielectron and Multiproton Chemical Transformation

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(36), С. 16219 - 16231

Опубликована: Сен. 2, 2022

The odyssey of photochemistry is accompanied by the journey to manipulate "electrons" and "protons" in time, space, energy. Over past decades, single-electron (1e-) photochemical transformations have brought marvelous achievements. However, as each photon absorption typically generates only one exciton pair, it exponentially challenging accomplish multielectron proton transformations. multistep differences thermodynamics kinetics urgently require us optimize light harvesting, expedite consecutive electron transfer, interaction catalysts with substrates, coordinate transfer furnish selective bond formations. Tandem catalysis enables orchestrating different events catalytic from subpicoseconds seconds, which facilitates redox chemistries brings consecutive, value-added reactivities. Joint efforts molecular material design, mechanistic understanding, theoretical modeling will bring synthetic opportunities for fuels, fertilizers, chemicals enhanced versatility, efficiency, selectivity, scalability, thus taking better advantage photons (i.e., sunlight) our sustainable society.

Язык: Английский

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Identification of Alkoxy Radicals as Hydrogen Atom Transfer Agents in Ce-Catalyzed C–H Functionalization

Journal of the American Chemical Society, Год журнала: 2022, Номер 145(1), С. 359 - 376

Опубликована: Дек. 20, 2022

The intermediacy of alkoxy radicals in cerium-catalyzed C–H functionalization via H-atom abstraction has been unambiguously confirmed. Catalytically relevant Ce(IV)–alkoxide complexes have synthesized and characterized by X-ray diffraction. Operando electron paramagnetic resonance transient absorption spectroscopy experiments on isolated pentachloro Ce(IV) alkoxides identified as the sole heteroatom-centered radical species generated ligand-to-metal charge transfer (LMCT) excitation. Alkoxy-radical-mediated hydrogen atom (HAT) verified kinetic analysis, density functional theory (DFT) calculations, reactions under strictly chloride-free conditions. These experimental findings establish critical role Ce-LMCT catalysis definitively preclude involvement chlorine radical. This study also reinforced necessity a high relative ratio alcohol vs Ce for selective alkoxy-radical-mediated HAT, seemingly trivial changes can lead to drastically different mechanistic pathways. Importantly, previously proposed radical–alcohol complex, postulated explain alkoxy-radical-enabled selectivities this system, examined scrutiny ruled out regioselectivity studies, experiments, high-level calculations. Moreover, peculiar selectivity generation LMCT homolysis heteroleptic analyzed back-electron (BET) may regulated efficiency formation ligand-centered radicals.

Язык: Английский

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Lewis Base–Boryl Radicals Enabled Borylation Reactions and Selective Activation of Carbon–Heteroatom Bonds

Accounts of Chemical Research, Год журнала: 2022, Номер 56(2), С. 169 - 186

Опубликована: Дек. 26, 2022

ConspectusThe past decades have witnessed tremendous progress on radical reactions. However, in comparison with carbon, nitrogen, oxygen, and other main group element centered radicals, the synthetic chemistry of boron radicals was less studied, mainly due to high electron-deficiency instability such 3-center-5-electron species. In 1980s, Roberts co-workers found that coordination a Lewis base (amines or phosphines) center could form 4-center-7-electron boryl (Lewis base-boryl LBRs) are be more stable. only limited applications were developed. 2008, Curran achieved breakthrough discovery N-heterocyclic carbene (NHC) which enable range reduction polymerization Despite these exciting findings, powerful valuable LBRs would expected, given structures reactivities easily modulated, provide ample opportunities discover new this Account, summary our key contributions LBR-enabled borylation reactions selective activation inert carbon-heteroatom bonds will presented.Organoboron compounds shown versatile chemical society, their syntheses rely principally ionic The development mechanistically different allows synthesizing products inaccessible by traditional methods. For purpose, we progressively developed series NHC-boryl mediated chemo-, regio-, stereoselective alkenes alkynes, wide variety structurally diverse organoboron molecules successfully prepared. utility borylated also demonstrated. Furthermore, disclosed photoredox protocol for oxidative generation enabled useful defluoroborylation arylboration reactions.Selective bond is an ideal way convert simple starting materials value-added products, while cleavage bonds, particular chemoselectivity control when multiple identical present similar environments, remains long-standing challenge. We envisaged finely tuning properties might solution address Recently, 4-dimethylaminopyridine (DMAP)-boryl promoted sequential C-F functionalization trifluoroacetic acid derivatives, α-C-F selectively snipped via spin-center shift mechanism. This strategy enables facile conversion abundantly available highly mono- difluorinated molecules. Encouraged finding, further three-step sequence construct all-carbon quaternary centers from trichloromethyl groups, where three C-Cl cleaved rational choice suitable precursors each step. dehydroxylative alkylation α-hydroxy carboxylic derivatives achieved, allowing efficient some biomass platform value products.

Язык: Английский

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Resurgence and advancement of photochemical hydrogen atom transfer processes in selective alkane functionalizations

Chemical Science, Год журнала: 2023, Номер 14(25), С. 6841 - 6859

Опубликована: Янв. 1, 2023

The selective functionalization of alkanes has long been recognized as a prominent challenge and an arduous task in organic synthesis. Hydrogen atom transfer (HAT) processes enable the direct generation reactive alkyl radicals from feedstock have successfully employed industrial applications such methane chlorination process,

Язык: Английский

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Merging Photoinduced Iron-Catalyzed Decarboxylation with Copper Catalysis for C–N and C–C Couplings

ACS Catalysis, Год журнала: 2023, Номер 13(3), С. 1678 - 1685

Опубликована: Янв. 13, 2023

We report a photoinduced iron/copper dual-catalytic strategy for the radical decarboxylation functionalization of aliphatic carboxylic acids. The ligand-to-iron charge transfer process under light was initially occurred to generate an unstabilized alkyl radical, and copper catalyst delivered enabled subsequent coupling reactions form C–N or C–C bonds. By merging iron-catalyzed with catalysis, this system allows smooth conversion wide range acids amination, decarboxylative dehydrogenation, alkylation efficiently. A variety complex drug natural molecules is applicable, suggesting that would facilitate rapid compound library synthesis benefit discovery pharmaceutical agents.

Язык: Английский

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