Mechanochemical Birch Reduction with Low Reactive Alkaline Earth Metals

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(20)

Published: March 4, 2024

Abstract Birch reduction and similar dissolved metal‐type transformations hold significant importance in the organic synthesis toolbox. Historically, field has been dominated by alkali metal reductants. In this study, we report that largely neglected, low‐reactive alkaline earth metals can become powerful affordable reductants when used a ball mill under essentially solvent‐free conditions, presence of ethylenediamine THF as liquid additives. Calcium reduce both electron‐deficient electron‐rich arenes, with yields products to those obtained lithium metal. Magnesium reveals enhanced reducing power, enabling benzoic acids while keeping aromatic moieties intact allows for chemoselective transformations. The developed mechanochemical approach uses readily available safer‐to‐handle metals, operates air ambient temperature be gram‐scale preparations. Finally, demonstrate conditions other reductive transformations, including amination, deoxygenation, dehalogenation, alkene alkyne reductions.

Language: Английский

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Iron-catalysed direct coupling of organosodium compounds

Nature Synthesis, Journal Year: 2025, Volume and Issue: unknown

Published: March 25, 2025

Abstract Sodium is one of the most abundant elements on Earth and a sustainable alternative to less metals such as lithium, which becoming increasingly depleted expensive. Traditionally, however, organosodium reagents have been considered highly reactive, engaging in uncontrollable reactions, result, they scarcely used organic synthesis, especially combination with transition-metal catalysis. Here we report use compounds C( sp 2 )–Na nucleophilic partners iron-catalysed oxidative homocoupling cross-coupling alkyl halides. Mechanistic investigations based preparation characterization putative organoiron intermediates reveal that bidentate additive coordinates both sodium iron centre, exerting control over catalytic reactivity. This two non-toxic metals, powered by molecular-level mechanistic understanding, expected open new avenues for organometallic synthesis.

Language: Английский

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Highly efficient and air-tolerant calcium-based Birch reduction using mechanochemistry

Chemistry Letters, Journal Year: 2024, Volume and Issue: 53(4)

Published: March 29, 2024

Abstract In this study, we report a mechanochemical protocol for highly efficient and air-tolerant calcium-based Birch reduction. The developed approach allows the use of readily available calcium metal as safer-to-handle reductant reduction various aromatic compounds. reaction was rapid desired dearomatization products were obtained in good yields within 15 min at ambient temperature. Notably, all synthetic operations can be performed under conditions without complicated setup involving inert gases. feasibility gram-scale synthesis demonstrated, further highlighting practical utility protocol.

Language: Английский

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Atmosphere Effects on Arene Reduction with Lithium and Ethylenediamine in THF

The Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 3, 2025

Birch reductions employing lithium metal have been performed mostly under argon due to concerns about forming nitrides from the reduction of dinitrogen if nitrogen. Although it is generally understood that inert atmospheres are standard for and Birch-type (lithium, ethylenediamine, t-BuOH, THF) reductions, atmosphere effect on has not studied. Herein, we report model substrates using ethylenediamine in THF various atmospheric conditions. The nitrogen afforded essentially same yields. Surprisingly, oxygen only perturbed yields some cases but also controlled regioselectivity a subset naphthalenes. We propose mechanism underlying unexpected oxygen-dependent This work shows may be account fraction oxygen-sensitive reductions.

Language: Английский

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A Mechanochemical [2+2+2] Cycloaddition Facilitated by a Cobalt(II) Catalyst and Piezoelectric Materials

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

In this study, we present the first general mechanochemical protocol for catalytic [2+2+2] cycloaddition of alkynes via a simple and inexpensive cobalt( ii )-based system in combination with piezoelectric BaTiO 3 .

Language: Английский

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Birch reductive arylation by mechanochemical anionic activation of polycyclic aromatic compounds

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: May 30, 2025

Birch reduction is a well-known process for transforming aromatic compounds. The of rings using alkali metals produces anionic species that react with protons or electrophiles. Generally, this reaction accompanied by significant limitations in the available nucleophiles, since most cases only alkyl halides and silyl chlorides are available. In particular, arylation unfunctionalized polycyclic hydrocarbons (PAHs), so-called reductive arylation, has not yet been investigated. Herein, we report mechanochemical activation lithium(0) wire, followed addition various fluoroarenes. Specifically, products but also formal C-H can be obtained from PAHs, achieving one-pot annulative π-extension to give nanographenes. This unique rarely achieved solution, shows interesting reactivity lithium metal fluoroarenes solid state.

Language: Английский

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Birch Reductive Arylation by Mechanochemical Anionic Activation of Polycyclic Aromatic Compounds

Published: Aug. 30, 2024

Birch reduction is a well-known process for producing aromatic compounds. The of rings using alkali metals produces anionic species that react with protons or electrophiles. However, this reaction generally accompanied by signifi-cant restrictions on the available substrates because only alkyl halides are in most cases. For example, reduction/transformation reactions related to alkylation compounds, whereas other elec-trophiles rare and have not yet been completely established. In particular, arylation unfunctionalized polycyclic ar-omatic hydrocarbons (PAHs), so-called reductive has investigated. Herein, we report re-ductive first time mechanochemical activation lithium(0) wire followed addition vari-ous fluoroarenes. Specifically, found products but also formal C–H were obtained from PAHs, achieving one-pot fissure-region annulative π-extension give nanogra-phenes. This newly unique rarely achieved solution, showed interesting reactivity metal lithium organofluorine compounds solid state.

Language: Английский

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Mechanochemical Birch Reduction with Low Reactive Alkaline Earth Metals

Angewandte Chemie, Journal Year: 2024, Volume and Issue: 136(20)

Published: March 4, 2024

Abstract Birch reduction and similar dissolved metal‐type transformations hold significant importance in the organic synthesis toolbox. Historically, field has been dominated by alkali metal reductants. In this study, we report that largely neglected, low‐reactive alkaline earth metals can become powerful affordable reductants when used a ball mill under essentially solvent‐free conditions, presence of ethylenediamine THF as liquid additives. Calcium reduce both electron‐deficient electron‐rich arenes, with yields products to those obtained lithium metal. Magnesium reveals enhanced reducing power, enabling benzoic acids while keeping aromatic moieties intact allows for chemoselective transformations. The developed mechanochemical approach uses readily available safer‐to‐handle metals, operates air ambient temperature be gram‐scale preparations. Finally, demonstrate conditions other reductive transformations, including amination, deoxygenation, dehalogenation, alkene alkyne reductions.

Language: Английский

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A Dual Cobalt-Photoredox Catalytic Approach for Asymmetric Dearomatization of Indoles with Aryl Amides via C-H Activation

Published: April 2, 2024

In this study, we unveil a novel method for the asymmetric dearomatization of indoles under cobalt/photoredox catalysis. By strategically activating C-H bonds amides and subsequent migratory insertion -bonds present in indole as reactive partner, achieve syn-selective tetrahydro-5H-indolo[2,3-c]isoquinolin-5-one derivatives with excellent yields enantiomeric excesses up to >99%. The developed operates without metal oxidant, relying solely on oxygen oxidant employing an organic dye photocatalyst irradiation. Control experiments stoichiometric studies elucidate reversible nature enantiodetermining activation step, albeit not being rate-determining. This study only expands horizon cobalt-catalyzed bond functionalization, but also showcases potential synergy between cobalt photoredox catalysis enabling synthesis complex molecules.

Language: Английский

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Mimicking Ozonolysis via Mechanochemistry: Internal Alkynes to 1,2‐Diketones using H₅IO₆

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(35)

Published: April 18, 2024

Utilizing periodic acid as an environmentally benign oxidizing agent, this study introduces a novel mechanochemical method that mimics ozonolysis to convert internal alkynes into 1,2-diketones, showcasing effective emulation of ozone's reactivity. Notably, oxidation occurs at room temperature in aerobic conditions, eliminating the need for toxic transition metals, hazardous oxidants, or expensive solvents. Through control experiments validating mechanism, substantial evidence supports concerted reaction pathway. This progress marks significant stride toward cleaner and more efficient chemical synthesis, mitigating environmental impact conventional processes. Assessing green chemistry metrics both solvent-free previously reported solvent-based methods, our eco-friendly protocol demonstrates E-factor 7.40, 51.7 % atom economy, 45.5 efficiency, 100 carbon 11.9 mass efficiency when solvents are not used.

Language: Английский

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