Highly Diastereo- and Enantioselective Synthesis of Tetrahydrobenzo[b]azocines via Palladium-Catalyzed [4 + 4] Cycloaddition

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(5), P. 2684 - 2690

Published: Feb. 12, 2021

The construction of N-heterocyclic eight-membered rings with good regio-, stereo-, and enantioselective control remains a formidable challenge in asymmetric catalysis. Herein, we report palladium-catalyzed [4 + 4] cycloaddition anthranils γ-methylidene-δ-valerolactones the presence Et3B, delivering highly functionalized tetrahydrobenzo[b]azocine derivatives high efficiency diastereoselectivities enantioselectivities (up to 92% yield, 20:1 dr, 99% ee). Moreover, complex substrates derived from natural products (bearing different functionalities) could be well-tolerated catalytic cycloaddition. mild reaction conditions, conjunction broad substrate scope (44 examples), level stereoselectivity, provide great potential build azocine compounds simple building blocks.

Language: Английский

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NiH-Catalyzed Hydroamination/Cyclization Cascade: Rapid Access to Quinolines

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(13), P. 7772 - 7779

Published: June 13, 2021

Despite the significant success of metal-H-catalyzed hydroamination methodologies, considerable limitations still exist in selective alkynes, especially for terminal alkynes. Herein, we develop a highly efficient NiH catalytic system that activates readily available alkynes cascade hydroamination/cyclization reaction with anthranils. This mild, operationally simple protocol is amenable to wide array including and internal, aryl alkyl, electron-deficient electron-rich ones, delivering structurally diverse quinolines useful excellent yields (>80 examples, up 93% yield). The utility this procedure exhibited late-stage functionalization several natural products concise synthesis an antitumor molecule graveolinine triplex DNA intercalator. Preliminary mechanistic experiments suggest alkenylnickel-mediated alkyne intramolecular cyclization/aromatization putative enamine intermediates.

Language: Английский

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Organic Azides: Versatile Synthons in Transition Metal‐Catalyzed C(sp²)−H Amination/Annulation for N‐Heterocycle Synthesis

Advanced Synthesis & Catalysis, Journal Year: 2020, Volume and Issue: 363(2), P. 411 - 424

Published: Nov. 14, 2020

Abstract Organic azides are highly reactive, which have long established as versatile building blocks in the assembly of structurally diverse N‐containing heterocycles. The conversion organic into high‐value compounds is great importance and a subject enormous current interest. Transition metal‐catalyzed C( sp 2 )−H amination/annulation provides powerful tool for transformation wide range biologically important heterocyclic frameworks. In this review, we aim to summarize recent progress on azides‐mediated N‐heterocycle synthesis enabled by transition metal catalysts. Representative strategies discussed detail, including catalytic systems, reaction scopes, limitations mechanisms. magnified image

Language: Английский

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Ruthenium-catalyzed oxidative coupling of vinylene carbonate with isoxazoles: access to fused anthranils

Chemical Communications, Journal Year: 2022, Volume and Issue: 58(28), P. 4476 - 4479

Published: Jan. 1, 2022

A ruthenium-catalyzed oxidative coupling of vinylene carbonate with isoxazoles has been developed to achieve the direct C-H formylmethylation a diverse array arylisoxazoles utilizing isoxazole ring as directing group. simple manipulation established reaction conditions leads formation fused-anthranils. Importantly, functions both formylmethyl cation equivalent through decarboxylation process and an acetylene equivalent. Control experiments were conducted elucidate plausible mechanism. This methodology is expected provide facile expeditious approach for synthesis

Language: Английский

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Transition Metal‐Mediated Functionalization of Isoxazoles: A Review

Asian Journal of Organic Chemistry, Journal Year: 2021, Volume and Issue: 10(12), P. 3127 - 3165

Published: Oct. 11, 2021

Abstract Isoxazoles are an important class of heterocycles with nitrogen and oxygen in a 1,2‐relationship. They find wide applications synthetic organic chemistry part several drug molecules. Since the last two decades, great progress has been achieved synthesis functionalization isoxazoles, which transition metal catalysis played pivotal role towards achieving this goal. In particular, (TM)‐mediated site‐selective functionalizations isoxazoles retain pharmacologically synthetically valuable isoxazole skeleton, highly appealing. This comprehensive review is solely dedicated to TM‐mediated wherein we have included as directing groups (DG) for TM‐catalyzed C−H reactions, direct functionalization, along cross‐coupling reactions annulation finally ring‐opening under TM‐catalysis also discussed. Also, incorporated discussions on reaction designs, their advantages limitations, mechanistic details challenges that need be addressed inspire medicinal chemists explore new arenas make use key scaffold.

Language: Английский

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Straightforward Construction and Functionalizations of Nitrogen‐Containing Heterocycles Through Migratory Insertion of Metal‐Carbenes/Nitrenes

The Chemical Record, Journal Year: 2021, Volume and Issue: 21(12), P. 3411 - 3428

Published: April 29, 2021

Abstract Nitrogen‐containing heterocycles are widely found in various biologically active substrates, pharmaceuticals, natural products and organic materials. Consequently, the continuous effort has been devoted towards development of straightforward, economical, environmentally acceptable, efficient ingenious methods for synthesis N ‐containing their functionalizations. Arguably, one most prominent direct strategy is regioselective C−H bond functionalizations which provide step atom economical approaches presence suitable coupling partners. In this context, site‐selective migratory insertion metal carbenes/nitrenes to desired bonds proven as a useful tool access functionalized nitrogen heterocycles. personal account, we highlight some our contemporary toward constructing via transition catalysed based on metal‐carbenes nitrenes.

Language: Английский

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Unusual Reactivity of 4-Vinyl Isoxazoles in the Copper-Mediated Synthesis of Pyridines, Employing DMSO as a One-Carbon Surrogate

Organic Letters, Journal Year: 2020, Volume and Issue: 22(15), P. 5855 - 5860

Published: July 9, 2020

An efficient protocol for the synthesis of nicotinate derivatives and tetrasubstituted pyridines through a copper-mediated cleavage isoxazoles has been developed. The highlight work is observation an unusual reactivity 4-vinyl under reaction conditions. DMSO serves as one-carbon surrogate generating active methylene group during to form two C–C bonds. This provides facile expeditious approach assembly densely substituted N-heterocyclic compounds.

Language: Английский

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Structural Evidence for Aromatic Heterocycle N–O Bond Activation via Oxidative Addition

Organometallics, Journal Year: 2023, Volume and Issue: 42(3), P. 211 - 217

Published: Jan. 3, 2023

Many methods report the scission of N–O bonds aromatic heterocycles and their subsequent functionalization. Oxidative addition is one presumed pathways through which bond activation with transition metals achieved. We first well-defined pathway (benz)isoxazole's oxidative addition. also provide control experiments, show that may be broken by strong inorganic reductants. These results highlight are susceptible to both reduction addition, has important implications for catalysis. Exploring reactivity these complexes toward a series electrophiles leads discovery Staudinger-type β-lactam synthesis upon reaction ketene. Finally, we demonstrate choice different metal/ligand combinations allows selective into either C–I or in presence other.

Language: Английский

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Nickel-Catalyzed Three-Component Carboamination/Cyclization of Alkynes To Access 2,3-Disubstituted Quinolines

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 23, 2025

Presented herein is a nickel-catalyzed chemo- and regioselective three-component tandem carboamination cyclization of terminal alkynes with organoboronic acids anthranils for facile modular access to 2,3-substituted quinolines. In this process, anthranil has dual roles: serving as an electrophilic aminating reagent redox buffer suppress the generation off-cycle Ni(0) complex. Moreover, anionic acetylacetonate (acac) ligand was found be vital ensure productive Ni(I)-Ni(III)-Ni(I) catalytic cycle.

Language: Английский

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Violet-Light-Induced Ring-Opening of Anthranils with Chlorodiazirines

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 30, 2025

A violet-light-induced ring-opening of anthranils with chlorodiazirines has been developed. The metal-free protocol provides a rapid and efficient approach to N-(2-carbonylaryl)benzamides in moderate good yields under mild conditions. reaction appears involve α-chlorocarbenes, which trigger the anthranils.

Language: Английский

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