Three-Component, Interrupted Radical Heck/Allylic Substitution Cascade Involving Unactivated Alkyl Bromides

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(22), С. 10173 - 10183

Опубликована: Май 7, 2020

Developing efficient and selective strategies to approach complex architectures containing (multi)stereogenic centers has been a long-standing synthetic challenge in both academia industry. Catalytic cascade reactions represent powerful means of rapidly leveraging molecular complexity from simple feedstocks. Unfortunately, carrying out Heck-type involving unactivated (tertiary) alkyl halides remains an unmet owing unavoidable β-hydride elimination. Herein, we show that modular, practical, general palladium-catalyzed, radical three-component coupling can indeed overcome the aforementioned limitations through interrupted Heck/allylic substitution sequence mediated by visible light. Selective 1,4-difunctionalization 1,3-dienes, such as butadiene, achieved employing different commercially available nitrogen-, oxygen-, sulfur-, or carbon-based nucleophiles bromides (>130 examples, mostly >95:5 E/Z, >20:1 rr). Sequential C(sp3)–C(sp3) C–X (N, O, S) bonds have constructed efficiently with broad scope high functional group tolerance. The flexibility versatility strategy illustrated gram-scale reaction streamlined syntheses ether, sulfone, tertiary amine products, some which would be difficult access via currently established methods.

Язык: Английский

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Visible Light-Induced Excited-State Transition-Metal Catalysis

Trends in Chemistry, Год журнала: 2019, Номер 1(5), С. 510 - 523

Опубликована: Июнь 1, 2019

Язык: Английский

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Photo-induced Decarboxylative Heck-Type Coupling of Unactivated Aliphatic Acids and Terminal Alkenes in the Absence of Sacrificial Hydrogen Acceptors

Journal of the American Chemical Society, Год журнала: 2018, Номер 140(47), С. 16360 - 16367

Опубликована: Ноя. 9, 2018

1,2-Disubstituted alkenes such as vinyl arenes, silanes, and boronates are among the most versatile building blocks that can be found in every sector of chemical science. We herein report a noble-metal-free method accessing olefins through photo-induced decarboxylative Heck-type coupling using alkyl carboxylic acids, one ubiquitous blocks, feedstocks. This transformation was achieved absence external oxidants synergistic combination an organo photo-redox catalyst cobaloxime catalyst, with H2 CO2 only byproducts. Both control experiments DFT calculations supported radical-based mechanism, which eventually led to development selective three-component aliphatic acrylates, arenes. More than 90 across wide range functionalities were effectively synthesized this simple protocol.

Язык: Английский

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Catalytic radical generation of π-allylpalladium complexes

Nature Catalysis, Год журнала: 2020, Номер 3(4), С. 393 - 400

Опубликована: Март 23, 2020

Язык: Английский

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Photoinduced Palladium-Catalyzed Carbofunctionalization of Conjugated Dienes Proceeding via Radical-Polar Crossover Scenario: 1,2-Aminoalkylation and Beyond

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(22), С. 9932 - 9937

Опубликована: Май 14, 2020

A photoinduced palladium-catalyzed 1,2-carbofunctionalization of conjugated dienes has been developed. This mild modular approach, which does not require employment exogeneous photosensitizers and external oxidants, allows for efficient highly regio- stereoselective synthesis a broad range allylic amines from readily available 1,3-dienes, alkyl iodides, amines. Employment O- C-nucleophiles toward oxyalkylation dialkylation products was also demonstrated. putative π-allyl palladium radical-polar crossover path is proposed as key event in this three-component coupling process. The utility protocol highlighted by its application derivatization several amine-containing drugs.

Язык: Английский

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Irradiation-Induced Palladium-Catalyzed Decarboxylative Heck Reaction of Aliphatic N-(Acyloxy)phthalimides at Room Temperature

Organic Letters, Год журнала: 2018, Номер 20(3), С. 888 - 891

Опубликована: Янв. 18, 2018

It is reported that Pd(PPh3)2Cl2 in combination with 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) under irradiation of blue LEDs efficiently catalyzes a decarboxylative Heck reaction vinyl arenes and heteroarenes aliphatic N-(acyloxy)phthalimides at room temperature. A broad scope secondary, tertiary, quaternary carboxylates, including α-amino acid derived esters, can be applied as amenable substrates high stereoselectivity. The experimental observation was explained by excitation-state reactivity the palladium complex to induce single-electron transfer activate N-(acyloxy)phthalimides, suppress undesired β-hydride elimination alkyl intermediates.

Язык: Английский

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Nickel and Palladium Catalysis: Stronger Demand than Ever

ACS Catalysis, Год журнала: 2022, Номер 12(2), С. 1180 - 1200

Опубликована: Янв. 5, 2022

Key similarities and differences of Pd Ni in catalytic systems are discussed. Overall, catalyze a vast number similar C–C C–heteroatom bond-forming reactions. However, the smaller atomic radius lower electronegativity Ni, as well more negative redox potentials low-valent species, often provide higher reactivity oxidative addition or insertion reactions persistence alkyl-Ni intermediates against β-hydrogen elimination, thus enabling activation reluctant electrophiles, including alkyl electrophiles. Another key point relates to stability open-shell electronic configurations Ni(I) Ni(III) compared with Pd(I) Pd(III). Nickel very involve interconvertible Ni(n+) active species variable oxidation states (Ni(0), Ni(I), Ni(II), Ni(III)). In contrast, involving Pd(III) still relatively less developed may require facilitation by special ligands merging photo- electrocatalysis. high Pd(n+) ensure their facile reduction Pd(0) under assistance numerous reagents solvents, providing concentrations molecular Pd1(0) complexes that can reversibly aggregate into Pdn clusters nanoparticles form cocktail Pdn(0) various nuclearities (i.e., values "n"). Ni(0) strong reductants; they sensitive deactivation air other oxidizers and, consequence, operate at catalyst loadings than palladium same The ease robustness versatility for catalysis, whereas variety enables diverse uncommon reactivity, albeit requiring efforts stabilization nickel systems. As discussion, we note easily "cocktail particles" different but (Pd1, Pdn, NPs), behave species" is stable nuclearities. Undoubtedly, there stronger demand ever not only develop improved efficient catalysts also understand mechanisms

Язык: Английский

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Excited-State Palladium-Catalyzed Radical Migratory Mizoroki–Heck Reaction Enables C2-Alkenylation of Carbohydrates

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(8), С. 3353 - 3359

Опубликована: Фев. 21, 2022

Excited-state palladium catalysis has emerged as a promising strategy for developing novel and valuable reactions. Herein, we report the first excited-state Pd-catalyzed 1,2-radical migratory Mizoroki–Heck reaction that enables C2-alkenylation of carbohydrates using readily available 1-bromosugars alkenes. The tolerates wide variety functional groups complex molecular architectures, including derivatives natural products marketed drugs. Preliminary mechanistic studies DFT calculations suggest involvement visible-light-induced photoexcitation Pd species, 1,2-spin-centered-shift (SCS) process, Heck-type cross-coupling reaction. expands reactivity profile provides streamlined protocol preparation C2-alkenylated carbohydrate mimetics to aid discovery development new therapeutics, agrochemicals, materials.

Язык: Английский

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Palladium Hydride-Enabled Hydroalkenylation of Strained Molecules

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(45), С. 20875 - 20883

Опубликована: Окт. 31, 2022

We report the first palladium hydride enabled hydroalkenylation of strained molecules. This new mild protocol proceeds via a regio- and chemoselective hydropalladation step, followed by photoinduced radical alkyl Heck reaction. methodology represents reactivity mode for molecules opens avenues catalysis. The reaction is compatible with wide range functional groups can be applied to complex structures, delivering diverse array highly valuable modifiable alkenylated cyclobutanes cyclopropanes. A hydroalkenylation/diastereoselective rearrangement cascade toward cyclopentene scaffold has also been demonstrated.

Язык: Английский

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Recent Advances in Visible Light Induced Palladium Catalysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 63(9)

Опубликована: Ноя. 14, 2023

Visible light-induced Pd catalysis has emerged as a promising subfield of photocatalysis. The hybrid nature radical species enabled wide array radical-based transformations otherwise challenging or unknown via conventional chemistry. In parallel to the ongoing pursuit alternative, readily available precursors, notable discoveries have demonstrated that photoexcitation can alter not only oxidative addition but also other elementary steps. This Minireview highlights recent progress in this area.

Язык: Английский

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