Copper-Catalyzed Oxidative Carbon-Carbon and/or Carbon-Heteroatom Bond Formation with O2 or Internal Oxidants

Iron-Catalyzed [3 + 2] Annulation of O-Acyl Oximes with 2-Hydroxy-1-Naphthoates for the Synthesis of Benzo[g]indoles

An iron-catalyzed [3 + 2] annulation of O-acyl oximes with 2-hydroxy-1-naphthoates has been developed. This strategy features the simultaneous activation of both substrates to form two radical intermediates. Subsequent selective C-N radical coupling followed by sequential condensation and 1,3-ester migration affords 1H- or 3H-benzo[g]indoles. In terms of the O-acyl oximes derived from 4-oxocyclohexanone and 4-azacyclohexanone, further ring-opening furnishes 2-(2-hydroxyethyl)- or 2-(2-aminoethyl)-1H-benzo[g]indoles.

Fluoroquinolone antibiotics trigger selective oxidation in the trace-Cu(II)/peroxydisulfate system: The synergistic effect of dual reactive sites in chemical structure

Research on transition metal-triggered advanced oxidation processes (TM-AOPs) has primarily focused on the regulation of catalysts and oxidants, but the alternative route that involves utilizing pollutant-derived electrons to enhance TM-AOPs has been largely overlooked. This study presents a case of selective degradation using fluoroquinolone antibiotics, with ofloxacin (OFX) selected as the model pollutant. Under the presence of PDS and trace Cu(II) (10 μM or 0.64 mg/L, below the limit of US drinking water standard), the OFX degradation rate was enhanced by 12.1 times compared to sole PDS oxidation. Notably, the system exhibited high pollutant selectivity and efficient oxidant utilization. Through various experimental methods, Cu(I) was confirmed as a crucial intermediate, while Cu(III) and •OH was identified as the predominant and secondary reactive oxidative species, respectively. The critical role of OFX was proved to be chelating with Cu(II) and facilitating the production of Cu(I). The degradation selectivity of OFX was attributed to the synergy of the chelating and oxidation sites in its chemical structure. Intramolecular single electron transfer occurred between the chelated OFX and Cu(III), leading to the Cu(III) reduction and OFX oxidation on the piperazine nitrogen atom. This study serves as a representative example of a greener pollutant-induced catalytic process based on the utilization of pollutant's electron bank, and offers novel insights into the correlation between a pollutant's chemical structure and its degradation selectivity.

Synthesis of Quinoline-Indole Hybrids through Cu(II)-Catalyzed Amination and Annulation between N-Oxides and o-Alkynylanilines

The synthesis of (iso)quinoline-indole hybrids by reacting (iso)quinoline N-oxides with o-alkynylanilines in the presence of a combination of copper(II) catalyst and a bidentate 2,2'-bipyridine ligand is described. The utility of this method was demonstrated through site-selective functionalization of the synthesized products. A plausible reaction pathway for site-selective amination followed by annulative indole formation was elucidated by a series of mechanistic investigations.

Recent Advances of C-S Coupling Reaction of (Hetero)Arenes by C-H Functionalization

Organic sulfur compounds encompass a vast and diverse variety of species that possess unique biological activity due to the presence of sulfur atoms or sulfur-containing functional groups. These compounds are widely present in natural products, pharmaceuticals, agricultural chemicals, and functional materials. In recent years, numerous sulfur-containing compounds such as thiols, thioethers, disulfides, thiourea, dimethyl sulfoxide, sulfonates and their derivatives, as well as sulfur-containing inorganic compounds, have been utilized as coupling agents to synthesize (hetero)aryl sulfides via C-H Functionalization. These novel transformations provide effective methods for constructing C-S bond of (hetero)arenes, while also expanding the scope of (hetero)aryl sulfides with the potential biological activity. Therefore, the synthesis of aryl sulfides through C-H bond functionalization has attracted widespread attention. This review mainly focuses on the construction of (hetero)aryl sulfides via C-H bond functionalization since 2015. We hope this review offers a useful conceptual overview and inspires further advancements in the efficient construction of C-S bonds.

Three Distinct Oxidation States (II/II, II/III, and III/III) of Diorganocopper Complexes

In this report, we present a structurally and spectroscopically characterized diorganocopper system in three distinct oxidation states: [CuIICuII] (1), [CuIICuIII] (2), and [CuIIICuIII] (3). These states are stabilized by a macrocyclic ligand scaffold featuring two square-planar coordination {C2 NHCN2 pyrazole}. We have analyzed the geometric and electronic structures using X-ray diffraction (XRD) and multiple spectroscopic methods including nuclear magnetic resonance (NMR), UV-vis, and electron paramagnetic resonance (EPR) spectroscopies, in combination with density functional theory (DFT) calculations. Remarkably, this study provides a structural determination of mixed-valence diorganocopper(II,III) complex 2, which is at the borderline between valence-trapped or charge-localized class I systems and charge moderately delocalized class II systems in Robin and Day classification. These findings enhance our understanding of the systematic structural and electronic changes that occur in diorganocopper complexes in response to redox transformations.

Photoredox/Copper-Cocatalyzed Domino Annulation of Oxime Esters and NH4SCN: Access to Fully Substituted 2-Aminothiazoles

Domino cyclization of oxime esters and NH4SCN facilitated by photoredox and copper cocatalysis has been established. Various structurally diverse fully substituted 2-aminothiazoles have been obtained in good yields at room temperature. It is featured by mild conditions, favorable functional group tolerance, and wide substrate scope. The present reaction is amenable to gram-scale synthesis, which is expected to find potential applications in organic synthesis and drug discovery. A plausible reaction mechanism is proposed.

A silylboronate-mediated strategy for cross-coupling of alkyl fluorides with aryl alkanes: mechanistic insights and scope expansion

The construction of C(sp3)-C(sp3) bonds is pivotal in organic synthesis; however, traditional methods involving alkyl halides are often limited by substrate tolerance and bond dissociation energies, particularly with alkyl fluorides. Herein, we report a silylboronate-mediated cross-coupling strategy that circumvents these challenges, enabling the efficient formation of C(sp3)-C(sp3) bonds between alkyl fluorides and aryl alkanes under mild conditions. Various alkyl fluorides have also been effectively utilized, demonstrating the versatility and broad applicability of this approach. The use of diglyme is critical for this transformation which encapsulates potassium cations and enhances the reaction efficiency. Conventional alkyl halides, including chlorides, bromides, and iodides, are also suitable for this transformation. Density functional theory (DFT) calculations were conducted on the silylboronate-mediated coupling reactions for the first time. Interestingly, while experimental results suggest a radical mechanism, DFT calculations indicate a preference for an ionic pathway.

Silver-Catalyzed Radical Umpolung Cross-Coupling of Silyl Enol Ethers with Activated Methylene Compounds: Access to Diverse Tricarbonyl Derivatives

A silver-catalyzed protocol for the intermolecular radical umpolung cross-coupling protocol of silyl enol ethers with activated methylene compounds is disclosed. The protocol exhibits excellent functional group tolerance, enabling the expedient preparation of a variety of tricarbonyl compounds. Preliminary mechanistic investigations suggest that the reaction proceeds through a process involving free radicals in which silver oxide has a dual role, acting as both a catalyst and a base.

Copper-Catalyzed [3 + 2] Annulation of O-Acyl Oximes with 4-Sulfonamidophenols for the Synthesis of 5-Sulfonamidoindoles and 2-Amido-5-sulfonamidobenzofuran-3(2H)-ones

A copper-catalyzed [3 + 2] annulation of O-acyl oximes with 4-sulfonamidophenols is developed. The advantage of this method lies in the concurrent double activation of two substrates to form nucleophilic enamines and electrophilic quinone monoimines. The substituent on the α-carbon of O-acyl oxime determines two different reaction pathways, thereby leading to the selective generation of 5-sulfonamidoindoles and 2-amido-5-sulfonamidobenzofuran-3(2H)-ones.

Divergent Synthesis of Multi-Substituted Aminotetralins via [4+2] Annulation of Aldimines with Alkenes by Rare-Earth-Catalyzed Benzylic C(sp3 )-H Activation

The search for efficient and selective methods for the divergent synthesis of multi-substituted aminotetralins is of much interest and importance. We report herein for the first time the diastereoselective [4+2] annulation of 2-methyl aromatic aldimines with alkenes via benzylic C(sp3 )-H activation by half-sandwich rare-earth catalysts, which constitutes an efficient route for the divergent synthesis of both trans and cis diastereoisomers of multi-substituted 1-aminotetralin derivatives from readily accessible aldimines and alkenes. The use of a scandium catalyst bearing a sterically demanding cyclopentadienyl ligand such as C5 Me4 SiMe3 or C5 Me5 exclusively afforded the trans-selective annulation products in the reaction of aldimines with styrenes and aliphatic alkenes. In contrast, the analogous yttrium catalyst, whose metal ion size is larger than that of scandium, yielded the cis-selective annulation products. This protocol features 100 % atom-efficiency, excellent diastereoselectivity, broad substrate scope, and good functional group compatibility. The reaction mechanisms have been elucidated by kinetic isotope effect (KIE) experiments and the isolation and transformations of some key reaction intermediates.

Palladium-Catalyzed Cyclization/Alkenylation of Ynone Oximes with Vinylsilanes for the Assembly of Isoxazolyl Vinylsilanes

A palladium-catalyzed cascade cyclization/alkenylation for the assembly of synthetically valuable isoxazolyl vinylsilane derivative has been accomplished. Easily accessible ynone oximes, and available vinylsilane agents were used as the reaction starting materials This protocol features broad substrate scope, good functional group tolerance, and good step- and atom-economy. Remarkably, this approach provides a new approach for the construction of structurally diverse isoxazolyl-containing vinylsilanes with high molecular complexity, showing a promising application in synthetic and pharmaceutical chemistry.

Conceptual advances in nucleophilic organophosphine-promoted transformations

Catalysis by trivalent nucleophilic organophosphines has emerged as an essential tool in organic synthesis. Several new organic transformations promoted by phosphines substantiate and complement the existing synthetic chemistry tools. Mere design of the substrate and reagent combinations has introduced new modes of reactivity patterns, which are otherwise difficult to achieve. These design considerations have led to the rapid build-up of complex molecular entities and laid a solid foundation to synthesise bioactive natural products and pharmaceuticals. This article presents an overview of some of the conceptual advances, including our contributions to nucleophilic organophosphine chemistry. The scope, limitations, mechanistic insights, and applications of these metal-free transformations are discussed elaborately.

Recent Advances in Aerobic Oxidative of C-H Bond by Molecular Oxygen Focus on Heterocycles

Aerobic oxidative cross-coupling represents one of the most straightforward and atom-economic methods for construction of C-C and C-X (X=N, O, S, or P) bonds using air as a sustainable external oxidant. The oxidative coupling of C-H bonds in heterocyclic compounds can effectively increase their molecular complexity by introducing new functional groups through C-H bond activation, or by formation of new heterocyclic structures through cascade construction of two or more sequential chemical bonds. This is very useful as it can increase the potential applications of these structures in natural products, pharmaceuticals, agricultural chemicals, and functional materials. This is a representative overview of recent progress since 2010 on green oxidative coupling reactions of C-H bond using O2 or air as internal oxidant focus on Heterocycles. It aims to provide a platform for expanding the scope and utility of air as green oxidant, together with a brief discussion on research into the mechanisms behind it.

Aerobic CuBr2-Catalyzed Oxidative Coupling Reaction of Amidines with Exocyclic α,β-Unsaturated Cycloketones for the Synthesis of Spiroimidazolines

A CuBr₂-catalyzed cascade reaction of amidines with exocyclic α,β-unsaturated cycloketones was developed, affording a large variety of spiroimidazolines in moderate to excellent yields. The reaction process involved the Michael addition and copper(II)-catalyzed aerobic oxidative coupling, in which O₂ from air acted as the oxidant and H₂O was the sole byproduct.

Copper-Catalyzed Annulation of O-Acyl Oximes with Cyclic 1,3-Diones for the Synthesis of 7,8-Dihydroindolizin-5(6H)-ones and Cyclohexanone-Fused Furans

A copper-catalyzed annulation of O-acyl oximes with cyclic 1,3-diones has been developed for the concise synthesis of 7,8-dihydroindolizin-5(6H)-ones and cyclohexanone-fused furans through the substituent-controlled selective radical coupling process. 2-Alkyl cyclic 1,3-diones undergo C-C radical coupling, while 2-unsubstituted cyclic 1,3-diones undergo C-O radical coupling.

Azide-Alkyne Cycloaddition Catalyzed by Copper(I) Coordination Polymers in PPM Levels Using Deep Eutectic Solvents as Reusable Reaction Media: A Waste-Minimized Sustainable Approach

Two air-stable copper(I)-halide coordination polymers 1 and 2 with NNS and NNO ligand frameworks were synthesized and successfully utilized as efficient catalysts in an important organic reaction, namely, copper-catalyzed azide-alkyne cycloaddition, which is generally conducted in a mixture of water and organic solvents. The azide-alkyne "click" reaction was successfully conducted in pure water at r.t. under aerobic conditions. Other green solvents, including ethanol and glycerol, were also effectively used. Finally, deep eutectic solvents as green and sustainable reaction media were successfully utilized. In deep eutectic solvents, complete conversion with excellent isolated yield was achieved in a short period of time (1 h) with low catalyst loading (1 mol %) at r.t. Full conversion could also be achieved within 24 h with ppm-level (50 ppm) catalyst loading at 70 °C. Optimized reaction conditions were used for the syntheses of a large number of 1,4-disubstituted 1,2,3-triazoles with various functionalities. Triazole products were easily isolated by simple filtration. The reaction media, such as water and deep eutectic solvents, were recovered and recycled in three consecutive runs. The limited waste production is reflected in a very low E-factor (0.3-2.8). Finally, the CHEM21 green metrics toolkit was employed to evaluate the sustainability credentials of different optimized protocols in various green solvents such as water, ethanol, glycerol, and deep eutectic solvents.

Ligand-assisted olefin-switched divergent oxidative Heck cascade with molecular oxygen enabled by self-assembled imines

Divergent oxidative Heck reaction has proven to be reliable for the rapid construction of molecular complexity, while olefins switched the outcome that remained underexplored.

Single Atom Catalysts for Selective Methane Oxidation to Oxygenates

Direct conversion of methane (CH₄) to C_1-2 liquid oxygenates is a captivating approach to lock carbons in transportable value-added chemicals, while reducing global warming. Existing approaches utilizing the transformation of CH₄ to liquid fuel via tandemized steam methane reforming and the Fischer-Tropsch synthesis are energy and capital intensive. Chemocatalytic partial oxidation of methane remains challenging due to the negligible electron affinity, poor C-H bond polarizability, and high activation energy barrier. Transition-metal and stoichiometric catalysts utilizing harsh oxidants and reaction conditions perform poorly with randomized product distribution. Paradoxically, the catalysts which are active enough to break C-H also promote overoxidation, resulting in CO₂ generation and reduced carbon balance. Developing catalysts which can break C-H bonds of methane to selectively make useful chemicals at mild conditions is vital to commercialization. Single atom catalysts (SACs) with specifically coordinated metal centers on active support have displayed intrigued reactivity and selectivity for methane oxidation. SACs can significantly reduce the activation energy due to induced electrostatic polarization of the C-H bond to facilitate the accelerated reaction rate at the low reaction temperature. The distinct metal-support interaction can stabilize the intermediate and prevent the overoxidation of the reaction products. The present review accounts for recent progress in the field of SACs for the selective oxidation of CH₄ to C_1-2 oxygenates. The chemical nature of catalytic sites, effects of metal-support interaction, and stabilization of intermediate species on catalysts to minimize overoxidation are thoroughly discussed with a forward-looking perspective to improve the catalytic performance.

Photoredox/copper cocatalyzed domino cyclization of oxime esters with TMSCN: access to antifungal active tetrasubstituted pyrazines

A photoredox/copper cocatalyzed domino cyclization of oxime esters with TMSCN has been developed. A range of structurally novel tetrasubstituted pyrazines have been obtained. This method features high bond-forming efficiency, high step economy, broad substrate scope, and gram-scale synthesis. Moreover, preliminary bioactivity evaluation of pyrazine products shows their promising antifungal activities.

Synthesis of Stable N-H Imines with a Benzo[7,8]indolizine Core and Benzo[7,8]indolizino[1,2-c]quinolines via Copper-Catalyzed Annulation of α,β-Unsaturated O-Acyl Ketoximes with Isoquinolinium N-Ylides

A copper-catalyzed annulation of α,β-unsaturated O-acyl ketoximes with isoquinolinium N-ylides has been developed for the concise synthesis of stable N-H imines with a benzo[7,8]indolizine core. When β-(2-bromoaryl)-α,β-unsaturated O-acyl ketoximes are used as the starting materials, a cascade cyclization occurs to afford the benzo[7,8]indolizino[1,2-c]quinolines.

Knoevenagel condensation triggered synthesis of dual-channel oxene based chemosensor: Discriminative spectrophotometric recognition of F-, CN- and HSO4- with breast cancer cell imaging, real sample analysis and molecular keypad lock applications

A novel oxene based unusual sensory receptor (HyMa) has been synthesized via.Knoevenagel condensation triggered carbon-heteroatom (oxygen) intramolecular bond formation reaction at room temperature for discriminative detection of multi-analytes like HSO₄^-, CN^- & F^- by spectro-photometric alterations with profound selectivity with the detection limit of 38 ppb, 18 ppb & 94 ppb respectively. Examination of the sensing mechanism was exhaustively investigated through several spectroscopic means like ¹H NMR, FT-IR, absorption and fluorescence spectra etc. In addition, quantum mechanical calculations like DFT and Loewdin spin population analyses also validated the rationality of the host-guest interaction. Apart from these, the reversible spectroscopic responses of HyMa towards F^- and Al³⁺ can imitate several complex logic functions that in turn help in preparing molecular keypad lock. This molecular keypad lock has the potential to protect the confidential information at the molecular scale. Additionally, the MTT assay of HyMa showed low cytotoxicity and membrane permeability indicating its attractive capability for bio-imaging towards triple negative breast cancer. HyMa-coated test strips could also be employed towards on-site detection of these deadly contaminants via "Dip Stick" approach without help of any instrumentation. In addition, HyMa has also been exploited for quantitative determination of HSO₄^- from various real water samples. In a nutshell, detection of lethal contaminants like CN^-, F^- & HSO₄^- at ppb level with in vitro live cell imaging has been explored with proper photophysical characterisation and theoretical calculations with real field applications.

Iron-Catalyzed Oxidative C-O and C-N Coupling Reactions Using Air as Sole Oxidant

We describe the oxygenation of tertiary arylamines, and the amination of tertiary arylamines and phenols. The key step of these coupling reactions is an iron-catalyzed oxidative C-O or C-N bond formation which generally provides the corresponding products in high yields and with excellent regioselectivity. The transformations are accomplished using hexadecafluorophthalocyanine-iron(II) (FePcF16 ) as catalyst in the presence of an acid or a base additive and require only ambient air as sole oxidant.

Insights into the Mechanism of Metal-Catalyzed Transformation of Oxime Esters: Metal-Bound Radical Pathway vs Free Radical Pathway

Controlling of radical reactivity by binding a radical to the metal center is an elegant strategy to overcome the challenge that radical intermediates are "too reactive to be selective". Yet, its application has seemingly been limited to a few strained-ring substrates, azide compounds, and diazo compounds. Meanwhile, first-row transition-metal-catalyzed (mainly, Fe, Ni, Cu) transformations of oxime esters have been reported recently in which the activation processes are assumed to follow free-radical mechanisms. In this work, we show by means of density functional theory calculations that the activation of oxime esters catalyzed by Fe(II) and Cu(I) catalysts more likely affords a metal-bound iminyl radical, rather than the presumed free iminyl radical, and the whole process follows a metal-bound radical mechanism. The as-formed metal-bound radical intermediates are an Fe(III)-iminyl radical (S_total = 2, S_Fe = 5/2, and S_iminyl = -1/2) and a Cu(II)-iminyl radical (S_total = 0, S_Cu = 1/2, and S_iminyl = -1/2). The discovery of such novel substrates affording metal-bound radical intermediates may facilitate the experimental design of metal-catalyzed asymmetric synthesis using oxime esters to achieve the desired enantioselectivity.

Merging strain-release and copper catalysis: the selective ring-opening cross-coupling of 1,2-oxazetidines with boronic acids

An unprecedented ring-opening cross-coupling of 1,2-oxazetidines with readily available arylboronic acids is achieved for the first time by copper catalysis. Unlike the known electrophilic oxygen reactivity in coupling with organometallic reagents, 1,2-oxazetidines were utilized as formaldimine precursors in this protocol. Remarkable features of this reaction include simple operation, inexpensive catalyst, broad scope and high regioselectivity, delivering a wide array of aminomethylation products. The practicality of this reaction was validated in the one-step downstream transformation of the obtained products into synthetically important molecules and late-stage modification of bioactive acids.

Copper-catalyzed aerobic benzylic C(sp3)-H lactonization of 2-alkylbenzamides via N-centered radicals

Herein, we describe the copper-catalyzed aerobic C(sp³)-H functionalization of 2-alkylbenzamides for the synthesis of benzolactones. This reaction proceeds via 1,5-hydrogen atom transfer of N-centered radicals directly generated by N-H bond cleavage and does not require the synthesis of pre-functionalized N-centered radical precursors or the use of strong stoichiometric oxidants.

Copper(I)-Catalyzed Direct Oxidative Annulation of 1,3-Dicarbonyl Compounds with Maleimides: Access to Polysubstituted Dihydrofuran Derivatives

An efficient annulation method for the synthesis of polysubstituted dihydrofurans from 1,3-dicarbonyl compounds and maleimides is described. The reactions can afford furo[2,3-c]pyrrole derivatives with satisfactory yields. The developed strategy realizes the direct oxidative double C(sp³)-H functionalization in the presence of copper(I) salts and 2-(tert-butylperoxy)-2-methylpropane. Meanwhile, this protocol features a mild reaction condition and simple catalytic system. A reaction mechanism involving a single electron oxidation is also proposed.

Facile synthesis of fully substituted 1H-imidazoles from oxime esters via dual photoredox/copper catalyzed multicomponent reactions

A novel and efficient photoredox/copper cocatalyzed domino cyclization of oxime esters, aldehydes, and amines has been achieved, affording a broad range of fully substituted 1H-imidazoles in good yields.

Palladium-catalyzed Lewis acid-regulated cascade annulation of alkynes with unactivated alkenes to access diverse α-methylene-γ-lactones

A palladium-catalyzed Lewis acid-regulated cascade annulation of alkynes with unactivated alkenes for the preparation of alkyl substituted α-methylene-γ-lactones with excellent Z/E selectivities was accomplished.

Accessing oxy-functionalized N-heterocycles through rose bengal and TBHP integrated photoredox C(sp3)–O cross-coupling

A C(sp3)–O coupling strategy is described involving tautomerizable N-heterocycles (phthalazinone, pyridne, pyrimidinone and quinoxalinone) carbonyl employing rose bengal as the photocatalyst and TBHP.

The copper-catalyzed radical aminophosphinoylation of maleimides with anilines and diarylphosphine oxides

The radical aminophosphinoylation of maleimides with anilines and diarylphosphine oxides.

Copper-iodine Co-catalyzed C−H Aminoalkenylation of Indoles via Temperature-controlled Selectivity Switch: Facile Synthesis of 2-Azolyl-3-alkenylindoles

An efficient copper-iodine co-catalyzed 2,3-difunctionalization of indoles with azoles and phenols via temperature-controlled selectivity switch has been developed for the green synthesis of 2-azolyl-3-alkenylindoles. The strategy involves the simultaneous establishment...

Copper-assisted Wittig-type olefination of aldehydes with p-toluenesulfonylmethyl isocyanide

A copper-assisted Wittig-type olefination of aldehydes and p-toluenesulfonyl isocyanide (TosMIC) is disclosed, providing an operationally simple approach to (E)-vinyl sulfone with various functional groups under mild reaction conditions.

Accessing Polycyclic Heteroarenes Enabled by Copper-Catalyzed Aerobic Oxidative C-H/C-H [4 + 2] Annulation of 3-Arylindole Derivatives

Several polycyclic aromatic hydrocarbons are delivered at room temperature by copper-catalyzed aerobic oxidative C-H/C-H [4 + 2] annulation of alkyl-substituted 3-arylindole derivatives. Specifically, dual aryl C-H functionalization is furnished under mild conditions through the 1,2-migration of copper catalyst and regioselective alkyne insertion. Mechanistic experiments demonstrate that the C-H bond cleavage on the indole and phenyl rings is not involved in the rate-limiting step.

Acetonitrile and benzonitrile as versatile amino sources in copper-catalyzed mild electrochemical C-H amidation reactions

A mild, efficient electrochemical approach to the site-selective direct C–H amidation of benzene and its derivatives with acetonitrile and benzonitrile has been developed. It has been shown that joint electrochemical oxidation of various arenes in the presence of a copper salt as a catalyst and nitriles leads to the formation of N-phenylacetamide from benzene and N-benzylacetamides from benzyl derivatives (up to 78% yield). A favorable feature of the process is mild conditions (room temperature, ambient pressure, no strong oxidants) that meet the criteria of green chemistry.

Different pathways of C–H transformation depending on the substrate nature and oxidation potential.

Aerobic Oxidative Cascade Thiolation and Cyclization to Construct Indole-Fused Isoquinolin-6(5H)-one Derivatives in EtOH

A practical method to construct sulfenylated indole-fused isoquinolin-6(5H)-one derivatives has been developed. Using eco-friendly ethanol as the solvent and air as the oxidant, this reaction could be compatible with sensitive molecular framework. The utility of the product was well illustrated by further transformations. Moreover, the reaction mechanism was investigated by control experiments.

Metal-Free Cascade Formation of Intermolecular C-N Bonds Accessing Substituted Isoindolinones under Cathodic Reduction

An electrochemical protocol for the construction of substituted isoindolinones via reduction/amidation of 2-carboxybenzaldehydes and amines has been realized. Under metal-free and external-reductant-free electrolytic conditions, the reaction achieves the cascade formation of intermolecular C-N bonds and provides a series of isoindolinones in moderate to good yields. The deuterium-labeling experiment proves that the hydrogen in the methylene of the product is mainly provided by H₂O in the system.