Oximes and Hydrazones in Bioconjugation: Mechanism and Catalysis

Chemical Reviews, Год журнала: 2017, Номер 117(15), С. 10358 - 10376

Опубликована: Июнь 22, 2017

The formation of oximes and hydrazones is employed in numerous scientific fields as a simple versatile conjugation strategy. This imine-forming reaction applied diverse polymer chemistry, biomaterials hydrogels, dynamic combinatorial organic synthesis, chemical biology. Here we outline developments this field, with special focus on the past ∼10 years developments. Recent strategies for installing reactive carbonyl groups α-nucleophiles into biomolecules are described. basic properties reactants products then reviewed, an eye to understanding reaction's mechanism how reactant structure controls rates equilibria process. work that has uncovered structural features new mechanisms speeding reaction, sometimes by orders magnitude, discussed. We describe recent studies have identified especially fast reacting aldehyde/ketone substrates effects lead rapid-reacting well. Among most effective been development substituents near aldehyde group either transfer protons at transition state or trap initially formed tetrahedral intermediates. In addition, efficient nucleophilic catalysts outlined, improving greatly upon aniline, classical catalyst imine formation. A number uses such second- third-generation bioconjugation cellular applications highlighted. While hydrazone oxime traditionally regarded being limited slow rates, 5 resulted completely overturning limitation; indeed, now one fastest reactions available conjugations biomaterials.

Язык: Английский

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Visible‐Light‐Photosensitized Aryl and Alkyl Decarboxylative Functionalization Reactions

Angewandte Chemie International Edition, Год журнала: 2019, Номер 58(31), С. 10514 - 10520

Опубликована: Июнь 4, 2019

Abstract Despite significant progress in aliphatic decarboxylation, an efficient and general protocol for radical aromatic decarboxylation has lagged far behind. Herein, we describe a strategy rapid access to both aryl alkyl radicals by photosensitized of the corresponding carboxylic acids esters followed their successive use divergent carbon–heteroatom carbon–carbon bond‐forming reactions. Identification suitable activator is key bypass competing single‐electron‐transfer mechanism “switch on” energy‐transfer‐mediated homolysis unsymmetrical σ‐bonds concerted fragmentation/decarboxylation process.

Язык: Английский

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Iminyl‐Radicals by Oxidation of α‐Imino‐oxy Acids: Photoredox‐Neutral Alkene Carboimination for the Synthesis of Pyrrolines

Angewandte Chemie International Edition, Год журнала: 2017, Номер 56(40), С. 12273 - 12276

Опубликована: Авг. 7, 2017

The visible-light-promoted decarboxylation of α-imino-oxy propionic acids for the generation iminyl radicals has been accomplished through use Ir(dFCF3 ppy)2 (dtbbpy)PF6 as a photoredox catalyst. Different from homolysis and single-electron reduction oxime derivatives, this strategy provides novel catalytic cycle alkene carboimination sequence comprising N-radical generation, radical cyclization, intermolecular conjugate addition to Michael acceptor, afford various pyrroline derivatives in an overall redox-neutral process. indolizidine alkaloid skeleton could be easily constructed derivative prepared by synthetic method.

Язык: Английский

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Metal-Involving Synthesis and Reactions of Oximes

Chemical Reviews, Год журнала: 2017, Номер 117(21), С. 13039 - 13122

Опубликована: Окт. 9, 2017

This review classifies and summarizes the past 10–15 years of advancements in field metal-involving (i.e., metal-mediated metal-catalyzed) reactions oximes. These are diverse nature have been employed for syntheses oxime-based metal complexes cage-compounds, oxime functionalizations, preparation new classes organic species, particular, a wide variety heterocyclic systems spanning small 3-membered ring to macroheterocycles. consideration gives general outlook reaction routes, mechanisms, driving forces underlines potential conversions species application various fields chemistry draws attention emerging putative targets.

Язык: Английский

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Divergent Iron‐Catalyzed Coupling of O‐Acyloximes with Silyl Enol Ethers

Chemistry - A European Journal, Год журнала: 2016, Номер 23(8), С. 1779 - 1783

Опубликована: Дек. 20, 2016

An iron-catalyzed coupling reaction of O-acyloximes and O-benzoyl amidoximes with silyl enol ethers is reported. The protocol provides access to functionalized pyrroles, 1,6-ketonitriles, pyrrolines imidazolines via carbon-centered radicals generated from an initially formed iminyl radical. intramolecular cyclization ring-opening processes the radical take place preferentially over reactions that proceed through a 1,3-hydrogen transfer, providing insights into oxime derivatives. cheap environmentally friendly iron catalyst, broad substrate scope functional group compatibility make this useful for synthesis valuable nitrogen-containing products.

Язык: Английский

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Carbon–Carbon Bond Cleavage for Late-Stage Functionalization

Chemical Reviews, Год журнала: 2023, Номер 123(22), С. 12313 - 12370

Опубликована: Ноя. 9, 2023

Late-stage functionalization (LSF) introduces functional group or structural modification at the final stage of synthesis natural products, drugs, and complex compounds. It is anticipated that late-stage would improve drug discovery's effectiveness efficiency hasten creation various chemical libraries. Consequently, products a productive technique to produce product derivatives, which significantly impacts biology development. Carbon-carbon bonds make up fundamental framework organic molecules. Compared with carbon-carbon bond construction, activation can directly enable molecular editing (deletion, insertion, atoms groups atoms) provide more efficient accurate synthetic strategy. However, selective unstrained still one most challenging projects in synthesis. This review encompasses strategies employed recent years for cleavage by explicitly focusing on their applicability functionalization. expands current discourse reactions providing comprehensive overview types bonds. includes C-C(sp), C-C(sp2), C-C(sp3) single bonds; double triple bonds, focus catalysis transition metals organocatalysts. Additionally, specific topics, such as ring-opening processes involving three-, four-, five-, six-membered rings, are discussed, exemplar applications these techniques showcased context bioactive molecules discovery. aims shed light advancements field propose potential avenues future research realm

Язык: Английский

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Visible-Light-Induced Energy-Transfer-Mediated Hydrofunctionalization and Difunctionalization of Unsaturated Compounds via Sigma-Bond Homolysis of Energy-Transfer Acceptors

ACS Catalysis, Год журнала: 2025, Номер 15(3), С. 1854 - 1941

Опубликована: Янв. 17, 2025

Over the past decade, visible-light-mediated energy-transfer (EnT) catalysis, particularly triplet–triplet (TTEnT) has emerged as a mild and environmentally friendly approach for diverse organic synthetic transformations. In contrast to photoredox which typically requires sacrificial electron donors or acceptors complete catalytic cycle, EnT photocatalysis generally proceeds with high atom economy while minimizing generation of wasteful byproducts. Furthermore, successful catalysis is contingent upon precise control redox potentials both photocatalysts substrates, strategies are primarily influenced by triplet energy compatibility between these entities. Considering growing importance photocatalysis, well hydrofunctionalization difunctionalization reactions in synthesis, this review systematically summarizes significant advancements EnT-enabled unsaturated compounds via sigma-bond homolysis over decade. Special emphasis placed on elucidating substrate scopes mechanistic scenarios. Additionally, discusses versatile applications methodologies addresses current challenges opportunities within evolving research field. This structured into six main categories based different types sigma-bonds undergoing homolysis. These include transformations mediated 1) N–O bond oxime esters other N,O-radical precursors; 2) N–S N-sulfonyl imines N,S-radical 3) chalcogen–chalcogen disulfides oxy/thio/selenosulfonates; 4) C–S tri/difluoromethylated sulfinates, acetylenic triflones, arylsulfonium salts; 5) C–X (X = halogen) halides; 6) acceptors. Through providing theoretical backgrounds along comprehensive overview currently employed acceptors, photosensitizers, contemporary EnT-induced compounds, aims serve an invaluable resource future innovations rapidly

Язык: Английский

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α‐Aminoxy‐Acid‐Auxiliary‐Enabled Intermolecular Radical γ‐C(sp³)−H Functionalization of Ketones

Angewandte Chemie International Edition, Год журнала: 2017, Номер 57(6), С. 1692 - 1696

Опубликована: Дек. 20, 2017

Abstract A method for site‐specific intermolecular γ‐C(sp 3 )−H functionalization of ketones has been developed using an α‐aminoxy acid auxiliary applying photoredox catalysis. Regioselective activation inert C−H bond is achieved by 1,5‐hydrogen atom abstraction oxidatively generated iminyl radical. Tertiary and secondary C‐radicals thus formed at the γ‐position imine functionality undergo radical conjugate addition to various Michael acceptors provide, after reduction hydrolysis, corresponding γ‐functionalized ketones.

Язык: Английский

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Photoredox-Catalyzed Intermolecular Remote C–H and C–C Vinylation via Iminyl Radicals

Organic Letters, Год журнала: 2018, Номер 20(17), С. 5523 - 5527

Опубликована: Авг. 23, 2018

A unified strategy for intermolecular remote C(sp3)–H and C–C vinylation of O-acyl oximes with vinyl boronic acids has been achieved. This is enabled by photoreductive generation iminyl radicals from under irradiation visible light. The translocated carbon-centered radicals, which are generated the through 1,5-hydrogen atom transfer or cleavage, can be vinylated acids. opens up a new approach to functionalization via cleavage provides an efficient versatile solution synthesis γ-vinylation ketones nitriles.

Язык: Английский

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Synthesis of Highly Substituted Pyridines through Copper‐Catalyzed Condensation of Oximes and α,β‐Unsaturated Imines

Angewandte Chemie International Edition, Год журнала: 2017, Номер 56(28), С. 8240 - 8244

Опубликована: Май 19, 2017

A copper-catalyzed condensation reaction of oxime acetates and α,β-unsaturated ketimines to give pyridine derivatives is reported. The features mild conditions, high functional-group compatibility, regioselectivity with respect unsymmetrical acetates, thus allowing the preparation a wide range polysubstituted pyridines, many which are not readily accessible by conventional methods.

Язык: Английский

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