Transition‐Metal‐Mediated and ‐Catalyzed C−F Bond Activation by Fluorine Elimination

Angewandte Chemie International Edition, Год журнала: 2018, Номер 58(2), С. 390 - 402

Опубликована: Июнь 28, 2018

Abstract The activation of carbon–fluorine (C−F) bonds is an important topic in synthetic organic chemistry. Metal‐mediated and ‐catalyzed elimination β‐ or α‐fluorine proceeds under milder conditions than oxidative addition to C−F bonds. initiated from organometallic intermediates having fluorine substituents on carbon atoms β α metal centers, respectively. Transformations through these processes (C−F bond cleavage), which are typically preceded by carbon–carbon (or carbon–heteroatom) formation, have been increasingly developed the past five years as methods. In this Minireview, we summarize applications transition‐metal‐mediated chemistry a historical perspective with early studies systematic recent studies.

Язык: Английский

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Nickel-catalyzed allylic defluorinative alkylation of trifluoromethyl alkenes with reductive decarboxylation of redox-active esters

Chemical Science, Год журнала: 2018, Номер 10(3), С. 809 - 814

Опубликована: Ноя. 7, 2018

Synthesis of functionalized gem-difluoroalkenes was achieved through nickel-catalyzed allylic defluorinative alkylation trifluoromethyl alkenes with reductive decarboxylation redox-active esters.

Язык: Английский

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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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Zn-Mediated Fragmentation of Tertiary Alkyl Oxalates Enabling Formation of Alkylated and Arylated Quaternary Carbon Centers

Journal of the American Chemical Society, Год журнала: 2018, Номер 141(2), С. 820 - 824

Опубликована: Дек. 20, 2018

Zn-mediated reduction of readily accessible dialkyl oxalates derived from tertiary alcohols provides an efficient approach to C–O bond fragmentation and alkyl radical formation. With MgCl2 as the indispensable additive Ni promoter, trapping with activated alkenes aryl–Ni intermediates allows for generation alkylated arylated all-carbon quaternary centers.

Язык: Английский

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Nickel-catalyzed formation of quaternary carbon centers using tertiary alkyl electrophiles

Chemical Society Reviews, Год журнала: 2021, Номер 50(6), С. 4162 - 4184

Опубликована: Янв. 1, 2021

This review provides a comprehensive summary of recent advances in nickel-catalyzed reactions employing tertiary alkyl electrophiles for the construction quaternary carbon centers.

Язык: Английский

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Recent Advances in Alkenyl sp² C–H and C–F Bond Functionalizations: Scope, Mechanism, and Applications

Chemical Reviews, Год журнала: 2022, Номер 122(24), С. 17479 - 17646

Опубликована: Окт. 14, 2022

Alkenes and their derivatives are featured widely in a variety of natural products, pharmaceuticals, advanced materials. Significant efforts have been made toward the development new practical methods to access this important class compounds by selectively activating alkenyl C(sp2)–H bonds recent years. In comprehensive review, we describe state-of-the-art strategies for direct functionalization sp2 C–H C–F until June 2022. Moreover, metal-free, photoredox, electrochemical also covered. For clarity, review has divided into two parts; first part focuses on currently available using different alkene as starting materials, second describes bond easily accessible gem-difluoroalkenes material. This includes scope, limitations, mechanistic studies, stereoselective control (using directing groups well metal-migration strategies), applications complex molecule synthesis where appropriate. Overall, aims document considerable advancements, current status, emerging work critically summarizing contributions researchers working fascinating area is expected stimulate novel, innovative, broadly applicable functionalizations coming

Язык: Английский

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Catalytic asymmetric reductive hydroalkylation of enamides and enecarbamates to chiral aliphatic amines

Nature Communications, Год журнала: 2021, Номер 12(1)

Опубликована: Фев. 26, 2021

Abstract To increase the reliability and success rate of drug discovery, efforts have been made to C( sp 3 ) fraction avoid flat molecules. -Rich enantiopure amines are most frequently encountered as chiral auxiliaries, synthetic intermediates for pharmaceutical agents bioactive natural products. Streamlined construction aliphatic has long regarded a paramount challenge. Mainstream approaches, including hydrogenation enamines imines, C–H amination, alkylation were applied synthesis with circumscribed skeleton structures; typically, carbon centre was adjacent an auxiliary aryl or ester group. Herein, we report mild general nickel-catalysed asymmetric reductive hydroalkylation effectively convert enamides enecarbamates into drug-like α-branched derivatives. This reaction involves regio- stereoselective hydrometallation enamide enecarbamate generate catalytic amount enantioenriched alkylnickel intermediate, followed by C–C bond formation via alkyl electrophiles.

Язык: Английский

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Nickel-Catalyzed Ligand-Controlled Selective Reductive Cyclization/Cross-Couplings

Accounts of Chemical Research, Год журнала: 2023, Номер 56(5), С. 515 - 535

Опубликована: Янв. 23, 2023

ConspectusThe use of quaternary stereocenters during lead candidate optimization continues to grow because improved physiochemical and pharmacokinetic profiles compounds with higher sp3 fraction. Pd-catalyzed redox-neutral alkene difunctionalization involving carbopalladation alkenes followed by nucleophilic-trapping σ-alkyl-palladium intermediates has been developed as an efficient method construct stereocenters. However, the low chemoselectivity air sensitivity organometallic nucleophiles, well their availability accessibility, limit scope application this elegant strategy. Recently, Ni-catalyzed reductive cross-coupling evolved into a privileged strategy easily valuable C(sp3)-C bonds. Despite great progress, enantioselective coupling C(sp3) electrophiles still relies on activated or functionalized alkyl precursors, which are often unstable require multiple steps prepare. Therefore, via selective cyclization/cross-coupling was developed. This not only offers robust practical alternative for traditional but also provides strategic complementarity electrophiles. In Account, we summarize latest results from our laboratory topic. These findings mainly include explorations in modulating enantioselectivity cyclization mode cyclization/cross-couplings.We will first discuss chiral heterocycles focus effects ligands, reductants, additives roles cross-coupling. A wide range have explored, including aryl halides, vinyl alkynyl gem-difluoroalkenes, CO2, trifluoromethyl alkenes, cyano The synthetic potential approach demonstrated synthesis biologically active natural products drug molecules. Second, detail how tune steric nickel catalysts modifying bipyridine ligands regiodivergent cyclization/cross-couplings. Specifically, bidentate favors exo-selective cyclization/cross-coupling, while carboxylic acid-modified ligand permits endo-selective cyclization/cross-coupling. We show activate amide substrate altering electronic properties substituents nitrogen, thereby enabling nucleophilic addition halides carbonyls. Further investigation led tunable cyclization/cross-couplings (addition carbonyl vs 7-endo-cyclization) divergent pharmacologically important 2-benzazepine frameworks. Finally, serendipitously discover that changing oxidation state can control migratory aptitude different groups, thus providing switchable skeletal rearrangement transformation is high value it represents conceptually unprecedented new C-C bond activation. Thus, Account summarizes methods allow formation using variety insight relationship between structure, substrate, selectivity.

Язык: Английский

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Nickel-Catalyzed Enantioselective Electrochemical Reductive Cross-Coupling of Aryl Aziridines with Alkenyl Bromides

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(11), С. 6270 - 6279

Опубликована: Март 7, 2023

An electrochemically driven nickel-catalyzed enantioselective reductive cross-coupling of aryl aziridines with alkenyl bromides has been developed, affording enantioenriched β-aryl homoallylic amines excellent E-selectivity. This electroreductive strategy proceeds in the absence heterogeneous metal reductants and sacrificial anodes by employing constant current electrolysis an undivided cell triethylamine as a terminal reductant. The reaction features mild conditions, remarkable stereocontrol, broad substrate scope, functional group compatibility, which was illustrated late-stage functionalization bioactive molecules. Mechanistic studies indicate that this transformation conforms stereoconvergent mechanism aziridine is activated through nucleophilic halide ring-opening process.

Язык: Английский

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Iron-catalysed reductive cross-coupling of glycosyl radicals for the stereoselective synthesis of C-glycosides

Nature Synthesis, Год журнала: 2022, Номер 1(3), С. 235 - 244

Опубликована: Фев. 17, 2022

Язык: Английский

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