Recent progress in cathodic reduction-enabled organic electrosynthesis: Trends, challenges, and opportunities

eScience, Journal Year: 2022, Volume and Issue: 2(3), P. 243 - 277

Published: April 23, 2022

Compared with general redox chemistry, electrochemistry using the electron as a potent, controllable, yet traceless alternative to chemical oxidants/reductants usually offers more sustainable options for achieving selective organic synthesis. With its environmentally benign features gradually being uncovered and studied, electrosynthesis is currently undergoing revival becoming rapidly growing area within synthetic community. Among electrochemical transformations, anodically enabled ones have been far extensively exploited than those driven by cathodic reduction, although both approaches are conceptually attractive. To stimulate development of cathodically reactions, this review summarizes recently developed reductive electrosynthetic protocols, discussing highlighting reaction features, substrate scopes, applications, plausible mechanisms reveal recent trends in area. Herein, reduction-enabled preparative transformations categorized into four types: reduction (1) unsaturated hydrocarbons, (2) heteroatom-containing carbon-based systems, (3) saturated C-hetero or C–C polar/strained bonds, (4) hetero-hetero linkages. Apart from net electroreductive few examples photo-electrosynthesis well paired electrolysis also introduced, which offer opportunities overcome certain limitations improve versatility. The electrochemically driven, transition metal-catalyzed cross-couplings that comprehensively discussed several other reviews not included here.

Language: Английский

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Radical Carbonyl Umpolung Arylation via Dual Nickel Catalysis

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(4), P. 1899 - 1909

Published: Jan. 18, 2022

The formation of carbon-carbon bonds lies at the heart synthetic organic chemistry and is widely applied to construct complex drugs, polymers, materials. Despite its importance, catalytic carbonyl arylation remains comparatively underdeveloped, due limited scope functional group tolerance. Herein we disclose an umpolung strategy achieve radical via dual catalysis. This redox-neutral approach provides a complementary method Grignard-type products from (hetero)aryl bromides aliphatic aldehydes, without need for pre-functionalization. A sequential activation, hydrogen-atom transfer, halogen atom transfer process could directly convert aldehydes corresponding ketyl-type radicals, which further react with aryl-nickel intermediates in overall polarity-reversal process. tolerates─among others─acidic groups, heteroaryl motifs, sterically hindered substrates has been late-stage modification drugs natural products.

Language: Английский

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Catalytic multicomponent reaction involving a ketyl-type radical

Nature Synthesis, Journal Year: 2022, Volume and Issue: 1(6), P. 464 - 474

Published: June 13, 2022

Language: Английский

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Electrophotocatalytic Reductive 1,2‐Diarylationof Alkenes with Aryl Halides and Cyanoaromatics

Chinese Journal of Chemistry, Journal Year: 2023, Volume and Issue: 41(16), P. 1921 - 1930

Published: April 7, 2023

Comprehensive Summary The radical‐mediated reductive functionalization of aryl halides has been extensively studied. However, the related intermolecular 1,2‐diarylation alkenes, using as radical sources, remains unexplored. Herein, a new electrophotocatalytic alkenes is reported and cyanoaromatics to produce polyarylated alkanes. Using synergistic cathodic reduction visible‐light photoredox catalysis, various electron‐rich electron‐deficient are combined with characterize broad substrate scope, excellent functional group compatibility, selectivity this reaction. Mechanistic investigations reveal that reaction may proceed via process initiated by generation radicals from terminated radical‐radical coupling cyanoaromatic anions.

Language: Английский

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Electroreductively Induced Radicals for Organic Synthesis

Molecules, Journal Year: 2023, Volume and Issue: 28(2), P. 857 - 857

Published: Jan. 15, 2023

Organic electrochemistry has attracted tremendous interest within the novel sustainable methodologies that have not only reduced undesired byproducts, but also utilized cleaner and renewable energy sources. Particularly, oxidative gained major attention. On contrary, reductive electrolysis remains an underexplored research direction. In this context, we discuss advances in transition-metal-free cathodically generated radicals for selective organic transformations since 2016. We highlight electroreductive reaction of alkyl radicals, aryl acyl silyl fluorosulfonyl trifluoromethoxyl radicals.

Language: Английский

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Recent Advances in C(sp³)–C(sp³) and C(sp³)–C(sp²) Bond Formation through Cathodic Reactions: Reductive and Convergent Paired Electrolyses

ACS Organic & Inorganic Au, Journal Year: 2021, Volume and Issue: 2(2), P. 126 - 147

Published: Dec. 22, 2021

The formation of C(sp3)–C(sp3) and C(sp3)–C(sp2) bonds is one the major research goals synthetic chemists. Electrochemistry commonly considered to be an appealing means drive redox reactions in a safe sustainable fashion has been utilized for C–C bond-forming reactions. Compared anodic oxidative methods, which have extensively explored, cathodic processes are much less investigated, whereas it can pave way alternative retrosynthetic disconnections target molecules discovery new transformations. This review provides overview on recent achievements construction via since 2017. It includes electrochemical reductions convergent paired electrolyses.

Language: Английский

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Nickel-Catalyzed Defluorinative Coupling of Aliphatic Aldehydes with Trifluoromethyl Alkenes

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(4), P. 2463 - 2471

Published: Feb. 3, 2022

A simple procedure is reported for the nickel-catalyzed defluorinative alkylation of unactivated aliphatic aldehydes. The process involves catalytic reductive union trifluoromethyl alkenes with aldehydes using a nickel complex 6,6'-disubstituted bipyridine ligand zinc metal as terminal reductant. protocol distinguished by its broad substrate scope, mild conditions, and setup. Reaction outcomes are consistent intermediacy an α-silyloxy(alkyl)nickel intermediate generated low-valent catalyst, silyl electrophile, aldehyde substrate. Mechanistic findings cyclopropanecarboxaldehyde provide insights into nature reactive intermediates illustrate fundamental reactivity differences that governed subtle changes in structure.

Language: Английский

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Reductive Cross‐Coupling of α‐Oxy Halides Enabled by Thermal Catalysis, Photocatalysis, Electrocatalysis, or Mechanochemistry

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(34)

Published: July 11, 2022

Herein, we report a reductive cross-coupling reaction of α-oxy halides, simply generated from aldehydes, with series C(sp2 )- and C(sp)-electrophiles. A wide range aryl heteroatom vinyl bromides, alkynyl acyl chlorides react unhindered hindered aldehyde-derived halides by providing protected alcohols as well α-hydroxy ketones. Noteworthy, the couplings are achieved not only through thermal catalysis use metal reductants but also photocatalysis, electrochemistry, mechanochemistry. The unrestricted interchange four strategies indicates their underlying mechanistic similarities. generation NiI intermediate is proposed to be key point for ketyl radical formation via single-electron transfer (SET) event, which was rationalized an array control experiments density functional theory (DFT) calculations.

Language: Английский

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Stirring‐Free Scalable Electrosynthesis Enabled by Alternating Current

Chemistry - A European Journal, Journal Year: 2023, Volume and Issue: 29(18)

Published: Jan. 3, 2023

Alternating current (AC) electrolysis is receiving increased interest as a versatile tool for mild and selective electrochemical transformations. This work demonstrates that AC can enable the concept of stirring-free reactor where periodic switch electrode polarity, inherent to AC, provides uniform across whole volume reactor. Such design implies straightforward approach scaling up electrosynthesis. was demonstrated on range transformations performed in three different RVC-packed reactors 50-mmol scale. Redox-neutral, oxidative, reductive processes were successfully implemented using suggested applicable frequency ranges further investigated types reactions. The advantages AC-enabled - such absence stirring maximized surface area electrodes provide possibility its universal application both small-scale screening experimentation large-scale preparative electrosynthesis without significant optimization needed between.

Language: Английский

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Radical Decyanations of Unactivated Carbon‐CN Bonds: Recent Achievements and Mechanistic Studies

Advanced Synthesis & Catalysis, Journal Year: 2023, Volume and Issue: 365(13), P. 2058 - 2091

Published: May 17, 2023

Abstract Decyanation is an important process in the synthesis of aromatic molecules studies pharmaceutical research, medical and materials sciences. In late‐stage modifications privileged carbo/heterocyclic scaffolds, radical‐type decyanation techniques have been devised to date. As a result, chemistry cyano‐involved conversions, hotly debated subject over past few decades, has advanced significantly. The cyano group (CN), on other hand, rarely acknowledged as good reaction site due its thermodynamic robustness. most recent advancements catalytic radical protocols that CN behaved leaving made are surveyed this article. Following introduction number different modes, reactions used activate C−CN bonds primarily categorized, text herein divided into three groups: (1) photo‐catalyzed transformations, (2) electro‐catalyzed (3) transition‐metal‐catalyzed or metal‐free transformations. With emphasis systems synthetic applications bond activation, review will provide readers with overview reactions.

Language: Английский

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