Direct Photocatalyzed Hydrogen Atom Transfer (HAT) for Aliphatic C–H Bonds Elaboration

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(2), P. 1875 - 1924

Published: Aug. 6, 2021

Direct photocatalyzed hydrogen atom transfer (d-HAT) can be considered a method of choice for the elaboration aliphatic C–H bonds. In this manifold, photocatalyst (PCHAT) exploits energy photon to trigger homolytic cleavage such bonds in organic compounds. Selective bond may achieved by judicious abstractor (key parameters are electronic character and molecular structure), as well reaction additives. Different classes PCsHAT available, including aromatic ketones, xanthene dyes (Eosin Y), polyoxometalates, uranyl salts, metal-oxo porphyrin tris(amino)cyclopropenium radical dication. The processes (mainly C–C formation) most cases carried out under mild conditions with help visible light. aim review is offer comprehensive survey synthetic applications d-HAT.

Language: Английский

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Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents

Chemical Society Reviews, Journal Year: 2021, Volume and Issue: 50(17), P. 9540 - 9685

Published: Jan. 1, 2021

Visible light-activated reactions continue to expand and diversify. The example shown here is a Birch reduction achieved by organophotoredox reagents.

Language: Английский

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Photocatalytic Late-Stage C–H Functionalization

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(8), P. 4237 - 4352

Published: Jan. 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.

Language: Английский

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A catalytic alkene insertion approach to bicyclo[2.1.1]hexane bioisosteres

Nature Chemistry, Journal Year: 2023, Volume and Issue: 15(4), P. 535 - 541

Published: Feb. 13, 2023

Language: Английский

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Recent progress in cathodic reduction-enabled organic electrosynthesis: Trends, challenges, and opportunities

eScience, Journal Year: 2022, Volume and Issue: 2(3), P. 243 - 277

Published: April 23, 2022

Compared with general redox chemistry, electrochemistry using the electron as a potent, controllable, yet traceless alternative to chemical oxidants/reductants usually offers more sustainable options for achieving selective organic synthesis. With its environmentally benign features gradually being uncovered and studied, electrosynthesis is currently undergoing revival becoming rapidly growing area within synthetic community. Among electrochemical transformations, anodically enabled ones have been far extensively exploited than those driven by cathodic reduction, although both approaches are conceptually attractive. To stimulate development of cathodically reactions, this review summarizes recently developed reductive electrosynthetic protocols, discussing highlighting reaction features, substrate scopes, applications, plausible mechanisms reveal recent trends in area. Herein, reduction-enabled preparative transformations categorized into four types: reduction (1) unsaturated hydrocarbons, (2) heteroatom-containing carbon-based systems, (3) saturated C-hetero or C–C polar/strained bonds, (4) hetero-hetero linkages. Apart from net electroreductive few examples photo-electrosynthesis well paired electrolysis also introduced, which offer opportunities overcome certain limitations improve versatility. The electrochemically driven, transition metal-catalyzed cross-couplings that comprehensively discussed several other reviews not included here.

Language: Английский

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Radical Carbonyl Umpolung Arylation via Dual Nickel Catalysis

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(4), P. 1899 - 1909

Published: Jan. 18, 2022

The formation of carbon-carbon bonds lies at the heart synthetic organic chemistry and is widely applied to construct complex drugs, polymers, materials. Despite its importance, catalytic carbonyl arylation remains comparatively underdeveloped, due limited scope functional group tolerance. Herein we disclose an umpolung strategy achieve radical via dual catalysis. This redox-neutral approach provides a complementary method Grignard-type products from (hetero)aryl bromides aliphatic aldehydes, without need for pre-functionalization. A sequential activation, hydrogen-atom transfer, halogen atom transfer process could directly convert aldehydes corresponding ketyl-type radicals, which further react with aryl-nickel intermediates in overall polarity-reversal process. tolerates─among others─acidic groups, heteroaryl motifs, sterically hindered substrates has been late-stage modification drugs natural products.

Language: Английский

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Visible-Light-Induced Divergent C–H Esterification/Alkylation of Quinoxalin-2(1H)-ones with Aldehydes under Mild Conditions

Organic Letters, Journal Year: 2025, Volume and Issue: 27(10), P. 2526 - 2531

Published: March 5, 2025

Herein, we introduce an efficient and straightforward strategy for the selective C-H esterification alkylation of quinoxalin-2(1H)-ones with aldehydes. A key feature our study is ability to perform both using different types The reaction system highly compatible a range aldehydes, yielding C3-esterified C3-alkylated products in moderate-to-good yields. applicability this approach further enhanced by its scalability through continuous-flow synthesis, late-stage modification significant molecules, product derivatization. Our mechanistic investigations reveal radical relay mechanism, triggered hydrogen atom transfer process.

Language: Английский

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Deoxygenative Functionalizations of Aldehydes, Ketones and Carboxylic Acids

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 61(10)

Published: Nov. 15, 2021

The simple and efficient conversion of carbonyl compounds into functionalized alkanes via deoxygenation is highly enabling in chemical synthesis. This Review covers the recent methodology development carboxyl deoxygenative functionalizations, highlighting some representative significant contributions this field. These advances are categorized based on reactivity patterns oxygenated feedstock compounds, including aldehydes, ketones carboxylic acids. Four types reactive intermediates arising from aldehydes during deoxygenation, namely, bis-electrophiles, carbenoids, bis-nucleophiles alkyl radical equivalents, presented, while acids mainly behave as tris-electrophiles when deoxygenated. In each subcategory, selected examples organized according to type bond formation discussed a generalized mechanistic perspective.

Language: Английский

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Synthesis of Cyclohexanones by a Tandem Photocatalyzed Annulation

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(16), P. 7030 - 7037

Published: March 22, 2022

The rapid synthesis of cyclic scaffolds is high importance to the chemistry community. Strategies for convergent substituted carbocycles and heterocycles remain underexplored despite plethora applications that these motifs have in pharmaceutical materials industries. Reported herein a tandem carbene photoredox-catalyzed process cycloalkanones via formal [5 + 1] cycloaddition. Featuring two distinct photoredox cycles novel α-oxidation benzylic ketones, this reaction offers mild approach construct contiguous C-C bonds eliminates need strong bases or expensive metal catalysts. utility method highlighted through various product diversification reactions allow access range important scaffolds.

Language: Английский

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Ketone–Olefin Coupling of Aliphatic and Aromatic Carbonyls Catalyzed by Excited-State Acridine Radicals

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(26), P. 11888 - 11896

Published: June 23, 2022

Ketone–olefin coupling reactions are common methods for the formation of carbon–carbon bonds. This reaction class typically requires stoichiometric or super quantities metal reductants, and catalytic variations limited in application. Photoredox catalysis has offered an alternative method toward ketone–olefin reactions, although most scope to easily reducible aromatic carbonyl compounds. Herein, we describe a mild, metal-free using excited-state acridine radical reductant as photoredox catalyst. We demonstrate both intramolecular intermolecular couplings aliphatic ketones aldehydes. Mechanistic evidence is also presented supporting "olefin first" mechanism.

Language: Английский

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