N–O Bond Activation by Energy Transfer Photocatalysis

Accounts of Chemical Research, Год журнала: 2022, Номер 55(17), С. 2526 - 2541

Опубликована: Авг. 20, 2022

ConspectusA radical shift toward energy transfer photocatalysis from electron under visible-light photoirradiation is often due to the greener prospects of atom and process economy. Recent advances in embrace unique strategies for direct small-molecule activation sometimes extraordinary chemical bond formation absence additional/sacrificial reagents. Selective requires careful selection substrates photocatalysts a perfect match with respect their triplet energies while having incompatible redox potentials prevent competitive pathways. Substrates containing labile N–O bonds are potential targets generating reactive key intermediates via access variety functionalized molecules. Typically, differential densities N O heteroatoms have been exploited generation either N- or O-centered by pathway. However, latest developments involve homolysis generate both radicals subsequent utilization diverse organic transformations, also sacrificial In this Account, we highlight our contributions field intermediates, coverage useful mechanistic insights. More specifically, well-designed bond-containing such as 1,2,4-oxadiazolines, oxime esters, N-indolyl carbonates, N-enoxybenzotriazoles were successfully utilized versatile transformations involving selective over high state energy. Direct N-, O-, C-centered (if decarboxylation follows) was achieved cross-couplings rearrangement processes. particular, open-shell nitrogen including N(sp2) N(sp3) nitrenes, utilized. Notably, diversified identical through control reaction conditions. 1,2,4-Oxadiazolines converted into spiro-azolactams iminyl presence 1O2, benzimidazoles, sulfoximines external sulfoxide reagent nitrene inert Besides, esters underwent intramolecular C(sp3)–N radical–radical coupling intermolecular combined transfer–hydrogen strategy. Furthermore, series electrochemical photophysical experiments well computational studies performed substantiate proposed energy-transfer-driven We hope that Account will serve guide rational design processes further bonds.

Язык: Английский

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Metal-Free Photochemical Imino-Alkylation of Alkenes with Bifunctional Oxime Esters

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(34), С. 15871 - 15878

Опубликована: Авг. 19, 2022

The concurrent installation of C-C and C-N bonds across alkene frameworks represents a powerful tool to prepare motifs that are ubiquitous in pharmaceuticals bioactive compounds. To construct such prevalent bonds, most difunctionalization methods demand the use precious metals or activated alkenes. We report metal-free, photochemically mediated imino-alkylation electronically diverse alkenes install both alkyl iminyl groups highly efficient manner. exceptionally mild reaction conditions, broad substrate scope, excellent functional group tolerance, facile one-pot protocol highlight utility this method privileged from readily available acid feedstocks. One key striking feature transformation is an electrophilic trifluoromethyl radical equally with electron-deficient electron-rich Additionally, dispersion-corrected density theory (DFT) empirical investigations provide detailed mechanistic insight into reaction.

Язык: Английский

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Spatial Decoupling of Redox Chemistry for Efficient and Highly Selective Amine Photoconversion to Imines

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(13), С. 7181 - 7189

Опубликована: Март 24, 2023

Light-driven primary amine oxidation to imines integrated with H2 production presents a promising means simultaneous of high-value-added fine chemicals and clean fuels. Yet, the effectiveness this strategy is generally limited by poor charge separation photocatalysts uncontrolled hydrogenation secondary amines. Herein, spatial decoupling proposed isolate redox chemistry at distinct sites photocatalysts, CoP core–ZnIn2S4 shell (CoP@ZnIn2S4) coaxial nanorods are assembled as proof-of-concept photocatalyst. Directional ultrafast carrier occurs between core ZnIn2S4 shell, confirmed in situ X-ray photoelectron spectroscopy, surface photovoltage transient absorption spectroscopy analyses. Toward photoconversion model substrate benzylamine N-benzylbenzaldimine, CoP@ZnIn2S4 exhibits 48-time higher rate >99% selectivity when compared (ca. 20% selectivity), detailed reaction mechanism has been verified diffuse reflectance infrared Fourier transform spectroscopy.

Язык: Английский

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Metal-Free Amino(hetero)arylation and Aminosulfonylation of Alkenes Enabled by Photoinduced Energy Transfer

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(30), С. 16630 - 16641

Опубликована: Июль 24, 2023

β-(Hetero)arylethylamines are privileged structural motifs found in many high-value organic molecules, including pharmaceuticals and natural products. To construct these important molecular skeletons, previous methods mainly achieved by amino(hetero)arylation reaction with the aid of transition metals preactivated substrates. Herein, we report a metal-free photoinduced intermolecular for single-step installation both (hetero)aryl iminyl groups across alkenes an efficient regioselective manner. This method shows broad scope (up to 124 examples) excellent tolerance various olefins─from simplest ethylene complex multisubstituted can all participate reaction. Furthermore, aminosulfonylation be also conducted presence sodium bisulfite as SO2 source.

Язык: Английский

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Catalyst Selection over an Electrochemical Reductive Coupling Reaction toward Direct Electrosynthesis of Oxime from NO_x and Aldehyde

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(9), С. 6294 - 6306

Опубликована: Фев. 20, 2024

Aqueous electrochemical coupling reactions, which enable the green synthesis of complex organic compounds, will be a crucial tool in synthetic chemistry. However, lack informed approaches for screening suitable catalysts is major obstacle to its development. Here, we propose pioneering reductive reaction toward direct electrosynthesis oxime from NOx and aldehyde. Through integrating experimental theoretical methods, screen out optimal catalyst, i.e., metal Fe that facilitates enrichment C–N key intermediates, all leading high yields (e.g., ∼99% yield benzaldoxime) over Fe. With divided flow reactor, achieve benzaldoxime production 22.8 g h–1 gcat–1 ∼94% isolated yield. This work not only paves way industrial mass via but also offers references catalyst selection other reactions.

Язык: Английский

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Photoredox-Catalyzed Alkene Acylesterification with Acyloxime Esters via C–C and Tertiary C–O Bond Formation

Organic Letters, Год журнала: 2025, Номер unknown

Опубликована: Янв. 7, 2025

We describe an efficient acyl esterification method for alkenes utilizing acyloxime esters as bifunctional reagents featuring radical acylation and congested C–O bond formation. This approach is characterized by mild photoredox conditions, high step atom economy, a broad substrate scope, excellent regioselectivity. A variety of valuable α-acyl hindered alcohol esters, including those obtained via gram-scale synthesis late-stage functionalization pharmaceutical molecules, were presented, demonstrating its synthetic potential practicability.

Язык: Английский

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Regioselective Access to Vicinal Diamines by Metal‐Free Photosensitized Amidylimination of Alkenes with Oxime Esters

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(44)

Опубликована: Сен. 9, 2022

A metal-free photosensitized protocol for regioselective diamination of alkene feedstocks over a single step was developed based on the rationally designed bifunctional reagent, thus affording range differentially protected 1,2-diamines in moderate to high yields. Mechanistic studies reveal that reaction is initiated with triplet-triplet energy transfer between thioxanthone catalyst and followed by fragmentation simultaneously generate long-lived iminyl radical transient amidyl radical. The excellent regioselectivity presumably stems from large reactivity difference two different N-centered species. This characterized regioselectivity, broad functional group tolerance, mild conditions, which would enrich diversity versatility facilitate diversity-oriented synthesis 1,2-diamine-containing complex molecule scaffolds.

Язык: Английский

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Mechanisms and Synthetic Strategies in Visible Light‐Driven [2+2]‐Heterocycloadditions

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(8)

Опубликована: Дек. 28, 2022

The synthesis of four membered heterocycles usually requires multi-step procedures and prefunctionalized reactants. A straightforward alternative is the photochemical [2+2]-heterocycloaddition between an alkene a carbonyl derivative, conventionally based on photoexcitation this latter. However, approach limited by absorption profile carbonyl, requiring in most cases use high-energy UV-light, that often results undesired side reactions and/or degradation reaction components. development new milder visible light-driven [2+2]-heterocycloadditions is, therefore, highly desirable. In Review, we highlight relevant achievements promoted light, with particular emphasis involved mechanisms. open challenges will also be discussed, suggesting possible evolutions, stimulating methodological developments field.

Язык: Английский

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Switchable Radical Carbonylation by Philicity Regulation

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(32), С. 14923 - 14935

Опубликована: Авг. 8, 2022

Carbonylation reactions involving CO as readily available C1 synthons have become one of the most important tools for construction carbonyl compounds from feedstock chemicals. Despite numerous catalytic methods carbonylation proceeding via ionic or radical pathways, an inherent limitation to these is need control switchable single and double carbonylative formation value-added products same simple starting materials. Here, we describe a new strategy that exploits photoredox catalysis regulate philicity amine coupling partners drive reactions. In carbonylation, amines were first transformed into nitrogen cations by single-electron transfer-oxidation coupled with form carbamoyl radicals, which further underwent cross-coupling incipient cyanoalkyl acyl radicals afford products. Upon addition stoichiometric 4-dimethylaminopyridine (DMAP), DMAP competitively traps initially formed relatively stabilized acyl-DMAP salts engaged in subsequent substitution nucleophilic produce The reaction proceeded smoothly excellent selectivity presence various nucleophiles at room temperature, generating valuable amides α-ketoamides versatile controlled fashion. Combined experimental computational studies provided mechanistic insights possible pathways.

Язык: Английский

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Copper-Catalyzed Three-Component Photo-ATRA-Type Reaction for Asymmetric Intermolecular C–O Coupling

ACS Catalysis, Год журнала: 2022, Номер 12(17), С. 10925 - 10937

Опубликована: Авг. 22, 2022

Atom transfer radical addition (ATRA) reaction of alkenes has had a significant impact on the field difunctionalization alkenes. Particularly, in three-component photo-ATRA-type processes, rich chemical space and structural diversity could be achieved by smart combination redox-active precursors third coupling components (e.g., halides, C-, N-, O-nucleophiles) under mild conditions. However, inherent complicated mechanisms involving chain or outer-sphere SET incipient intermediates have led to dearth general catalytic methods for highly enantioselective variants, especially those regarding asymmetric intermolecular C–O bond formation. Here, we report visible-light-induced copper-catalyzed with oxime esters carboxylic acids. In this process, cross-coupling between sp3-hybridized carbon radicals acids was enabled formation an aryl π-bond-engaged [σ + π]-copper complex. This working hypothesis renders naphthyl extended conjugation suitable substrates allows good stereocontrol. exhibits broad substrate scope high functional group tolerance respect each component, giving desired products generally yields enantioselectivity (>70 examples; up 97% ee). Preliminary experimental computational studies are also performed gain insight into mechanism stereoregulatory elements. finding provides promising platform development other benzylic-type radical-based reactions.

Язык: Английский

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