Programmed alternating current optimization of Cu-catalyzed C-H bond transformations

Science, Год журнала: 2024, Номер 385(6705), С. 216 - 223

Опубликована: Июль 11, 2024

Direct current (DC) electrosynthesis, which has undergone optimization over the past century, plays a pivotal role in variety of industrial processes. Alternating (AC) characterized by polarity reversal and periodic fluctuations, may be advantageous for multiple chemical reactions, but apparatus, principles, application scenarios remain underdeveloped. In this work, we introduce protocol programmed AC (pAC) electrosynthesis that systematically adjusts currents, frequencies, duty ratios. The representative pAC waveforms facilitates copper-catalyzed carbon-hydrogen bond cleavage cross-coupling difunctionalization reactions exhibit suboptimal performance under DC oxidation conditions. Moreover, observing catalyst dynamic variation diverse waveform applications provides mechanistic insight.

Язык: Английский

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Electrochemical Dearomative Spirocyclization

Chemistry - An Asian Journal, Год журнала: 2023, Номер 18(9)

Опубликована: Март 15, 2023

Electrochemical dearomative spirocyclization serves as a green and sustainable approach to convert the flat, two-dimension aromatic feedstock into value-added three-dimension spirocyclic architectures. This review highlights recent advances, emphasizes mechanistic discussions, showcases synthetic applications of this emerging versatile powerful transformation.

Язык: Английский

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Regiodivergent C−H Acylation of Arenes by Switching from Ionic‐ to Radical‐Type Chemistry Using NHC Catalysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(27)

Опубликована: Апрель 24, 2023

The Friedel-Crafts acylation reaction, which belongs to the class of electrophilic aromatic substitutions is a highly valuable and versatile reaction in synthesis. Regioselectivity predictable determined by electronic as well steric factors (hetero)arene substrate. Herein, radical approach for arenes heteroarenes presented. C-H achieved through mild cooperative photoredox/NHC catalysis with cross-coupling an arene cation NHC-bound ketyl key step. As compared classical acylation, regiodivergent outcome observed upon switching from ionic mode. In these divergent reactions, aroyl fluorides act reagents both process.

Язык: Английский

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Confronting the Mysteries of Oxidative Reactive Species in Advanced Oxidation Processes: An Elephant in the Room

Environmental Science & Technology, Год журнала: 2024, Номер 58(42), С. 18496 - 18507

Опубликована: Окт. 9, 2024

Advanced oxidation processes (AOPs) are rapidly evolving but still lack well-established protocols for reliably identifying oxidative reactive species (ORSs). This Perspective presents both the radical and nonradical ORSs that have been identified or proposed, along with extensive controversies surrounding mechanisms. Conventional identification tools, such as quenchers, probes, spin trappers, might be inadequate analytical demands of systems in which multiple coexist, often yielding misleading results. Therefore, challenges these complex, short-lived, transient must fully acknowledged. Refining methods is necessary, supported by rigorous experiments innovative paradigms, particularly through kinetic analysis based on situ spectroscopic techniques multiple-probe strategies. To demystify complex ORSs, future efforts should made to develop advanced tools strategies enhance mechanism understanding. In addition, integrating real-world conditions into experimental designs will establish a reliable framework fundamental studies, providing more accurate insights effectively guiding design AOPs.

Язык: Английский

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Molecularly Imprinted Polymer-based voltammetric sensor for amino acids/indazole derivatives synthetic cannabinoids detection

Analytica Chimica Acta, Год журнала: 2023, Номер 1288, С. 342151 - 342151

Опубликована: Дек. 18, 2023

Synthetic cannabinoids (SCs) are a broad class of illicit drugs that classified according to the chemical structure aromatic core they present (i.e., indole, imidazole, pyrrole) and their detection is still challenge, despite widespread diffusion. The identification specific SC in complex matrices, such as real samples with rapid, economic analytical device useable directly field, highly desirable, it can provide immediate reliable information eventually addresses more targeted analyses.

Язык: Английский

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Divergent Electrochemical Synthesis of Indoles through pK_a Regulation of Amides: Synthetic and Mechanistic Insights

Chemistry - A European Journal, Год журнала: 2024, Номер 30(20)

Опубликована: Янв. 31, 2024

A divergent synthetic approach to access highly substituted indole scaffolds is illustrated. By virtue of a tunable electrochemical strategy, distinct control over the C-3 substitution pattern was achieved by employing two analogous 2-styrylaniline precursors. The chemoselectivity governed fine-tuning acidity amide proton, relying on appropriate selection N-protecting groups, and assisted reactivity electrogenerated intermediates. Detailed mechanistic investigations based cyclic voltametric experiments computational studies revealed crucial role water additive, which assists proton-coupled electron transfer event for acidic precursors, followed an energetically favorable intramolecular C-N coupling, causing exclusive fabrication unsubstituted indoles. Alternatively, implementation cationic olefin activator delivers indoles through preferential nucleophilic nature N-acyl amides. This judicious groups regulate pK

Язык: Английский

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2,2′‐Thienoviologens with Low Reduction Potential for Electrochromism and Visible‐Light‐Driven Hydrogen Evolution Using g‐C₃N₄‐Based Composites via Hydrogen Bonds

Advanced Energy Materials, Год журнала: 2024, Номер 14(26)

Опубликована: Май 8, 2024

Abstract A series of sulfur‐bridged 2,2′‐viologens, 2,2′‐thienoviologens (2,2′‐SV 2+ ) with propyl bridge and hydroxyl bridges, are synthesized for the first time. The exhibited improved visible‐light absorption, narrow energy gap, more negative reduction potential (160 mV lower than 4,4′‐thienoviologens) stable free radical states compared 4,4′‐thienoviologens parent 2,2′‐viologens. utilization femtosecond transient absorption (fs‐TA) demonstrated that 2,2′‐thienoviologen can produce distinct charge‐separated under visible light excitation. Due to their excellent photophysical electrochemical properties, used electrochromic devices combined g‐C 3 N 4 via hydrogen bonds catalytic production. Based on advantageous electron‐donating properties 2,2′‐SV , release efficiency 2,2′‐thienoviologens‐modified composites is 8542 µmol·h −1 ·g a value highest reported production from organic small‐molecule‐modified 78 times higher unmodified . This study presents concise method convert solar broaden applications 2,2′‐viologens in photocatalytic systems.

Язык: Английский

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Copper/Iodine Co-catalyzed Oxygenative Transannulation of Tryptamines Enables Direct Synthesis of Donaxaridine and Its Derivatives

Organic Letters, Год журнала: 2024, Номер 26(3), С. 625 - 630

Опубликована: Янв. 11, 2024

We report a general copper/iodine co-catalyzed oxygenative transannulation strategy using readily available tryptamines. Molecular oxygen and water are used as sources provide direct access to the donaxaridine scaffold its derivatives. This methodology is applied efficient synthesis of natural products donaxaridine, chimonamidine, donaxanine, donaxarine, aline in just one or two steps. The tryptamines, albeit with oxy-sensitive dialkyl N-H groups, selectively oxidized through single-electron transfer dioxygenation process.

Язык: Английский

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Benzylic C(sp3)–H Functionalization via Copper-Catalyzed [3+3] Radical Cycloaddition

ACS Catalysis, Год журнала: 2024, Номер 14(8), С. 5605 - 5611

Опубликована: Март 29, 2024

The development of benzylic C(sp3)–H functionalization methods for the assembly derivatives has been extensively explored in recent years. However, engagement carbon and its adjacent C=C bond as a C3 synthon cycloaddition reaction via direct C–H activation is rare. Herein, we report copper-catalyzed [3+3] radical through to construct six-membered cyclohexane-type rings. In this reaction, 2-benzylic an indole selectively activated serves that reacts highly chemoselective intermolecular self-[3+3] cross-[3+3] pathways. Multiple symmetric nonsymmetric polycyclic hexahydrocarbazole scaffolds with hexacyclic 6/5/5/6/5/5/6 pentacyclic 6/5/5/6/5/6 ring systems are synthesized high efficiency chemoselectivity using strategy. Inspired by unique addition pathway cycloaddition, controllable construction C3a-alkylated pyrroloindolines was also developed.

Язык: Английский

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Divergent Photosensitizer Controlled Reactions of 4‐Hydroxycoumarins and Unactivated Olefins: Hydroarylation and Subsequent [2+2] Cycloaddition

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(45)

Опубликована: Сен. 26, 2023

Herein, we report a photoinduced approach for hydroarylation of unactivated olefins using 4-hydroxycoumarins as the arylating reagent. Key to success this reaction is conversion nucleophilic into electrophilic carbon radicals via photocatalytic arene oxidation, which not only circumvents polarity-mismatch issue encountered under ionic conditions but also accommodates broad substrate scope and inhibits side reactions that were previously observed. Moreover, divergent reactivity was achieved by changing photocatalyst, enabling subsequent [2+2] cycloaddition deliver cyclobutane-fused pentacyclic products are otherwise challenging access in high yields with diastereoselectivity. Mechanistic studies have elucidated mechanism origin reactivity.

Язык: Английский

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