CuI Nanoparticles for C−N and C−O Cross Coupling of Heterocyclic Amines and Phenols with Chlorobenzenes

Unsupported Copper Nanoparticles in the Arylation of Amines

Commercially available copper and copper (II) oxide nanoparticles (CuNPs and CuO NPs) were characterized using TEM and electronography methods to elucidate their true average size and composition. The catalytic amine arylation using unsupported copper nanoparticles differing in their size and copper oxidation state was investigated. The reaction of the model iodobenzene with n-octylamine was shown to be successfully catalyzed by CuNPs of average size 25 and 10/80 nm in the presence of the ligands such as 2-isobutyrylcyclohexanone (L1) and rac-1,1′-bi-2-naphthol (BINOL, L2), giving high yields (up to 95%) of the target N-octylaniline. CuO in bulk and nano forms was shown to be almost equally efficient in this process. Studies on the Cu-catalyzed amination of substituted iodobenzenes and 2-iodopyridine, as well as the arylation of different aliphatic amines and NH-heterocycles, verified that CuNPs (25 or 10/80 nm) with L1 and L2 are the most versatile and efficient nanocatalysts for a variety of substrates. Investigation of copper leaching under different conditions was carried out.

Copper-Catalyzed Reactions of Aryl Halides with N-nucleophiles and Their Possible Application for Degradation of Halogenated Aromatic Contaminants

This review summarizes recent applications of copper or copper-based compounds as a nonprecious metal catalyst in N-nucleophiles-based dehalogenation (DH) reactions of halogenated aromatic compounds (Ar-Xs). Cu-catalyzed DH enables the production of corresponding nonhalogenated aromatic products (Ar-Nu), which are much more biodegradable and can be mineralized during aerobic wastewater treatment or which are principally further applicable. Based on available knowledge, the developed Cu-based DH methods enable the utilization of amines for effective cleavage of aryl-halogen bonds in organic solvents or even in an aqueous solution.

Copper nanocatalysts applied in coupling reactions: a mechanistic insight

Copper-based nanocatalysts have seen great interest for use in synthetic applications since the early 20th century, as evidenced by the exponential number of contributions reported (since 2000, more than 48 000 works published out of about 81 300 since 1900; results from SciFinder using "copper nanocatalysts in organic synthesis" as keywords). These huge efforts are mainly based on two key aspects: (i) copper is an Earth-abundant metal with low toxicity, leading to inexpensive and eco-friendly catalytic materials; and (ii) copper can stabilize different oxidation states (0 to +3) for molecular and nanoparticle-based systems, which promotes different types of metal-reagent interactions. This chemical versatility allows different pathways, involving radical or ionic copper-based intermediates. Thus, copper-based nanoparticles have become convenient catalysts, in particular for couplings (both homo- and hetero-couplings), transformations that are involved in a remarkable number of processes affording organic compounds, which find interest in different fields (medicinal chemistry, natural products, drugs, materials, etc.). Clearly, this richness in reactivity makes understanding the mechanisms more complex. The present review focuses on the analysis of reported contributions using monometallic copper-based nanoparticles as catalytic precursors applied in coupling reactions, paying attention to those shedding light on the reaction mechanism.

Electrochemical-induced hydroxylation of aryl halides in the presence of Et3N in water

A thorough study of mild and environmentally friendly electrochemical-induced hydroxylation of aryl halides without a catalyst is presented. The best protocol consists of hydroxylation of different aryl iodides and aryl bromides by water solution in the presence of Et3N under air, affording the target phenols in good isolated yields. Moreover, aryl chlorides were successfully employed as substrates. This methodology also provides a direct pathway for the formation of deoxyphomalone, which displayed a significant anti-proliferation effect.

The Influence of Copper on Halogenation/Dehalogenation Reactions of Aromatic Compounds and Its Role in the Destruction of Polyhalogenated Aromatic Contaminants

The effect of copper and its compounds on halogenation and dehalogenation of aromatic compounds will be discussed in the proposed article. Cu oxidized to appropriate halides is an effective halogenation catalyst not only for the synthesis of halogenated benzenes or their derivatives as desired organic fine chemicals, but is also an effective catalyst for the undesirable formation of thermodynamically stable and very toxic polychlorinated and polybrominated aromatic compounds such as polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans accompanied incineration of waste contaminated with halogenated compounds or even inorganic halides. With appropriate change in reaction conditions, copper and its alloys or oxides are also able to effectively catalyze dehalogenation reactions, as will be presented in this review.

Copper-catalyzed Goldberg-type C-N coupling in deep eutectic solvents (DESs) and water under aerobic conditions

An efficient and selective N-functionalization of amides is first reported via a CuI-catalyzed Goldberg-type C-N coupling reaction between aryl iodides and primary/secondary amides run either in Deep Eutectic Solvents (DESs) or water as sustainable reaction media, under mild and bench-type reaction conditions (absence of protecting atmosphere). Higher activities were observed in an aqueous medium, though the employment of DESs expanded and improved the scope of the reaction to include also aliphatic amides. Additional valuable features of the reported protocol include: (i) the possibility to scale up the reaction without any erosion of the yield/reaction time; (ii) the recyclability of both the catalyst and the eutectic solvent up to 4 consecutive runs; and (iii) the feasibility of the proposed catalytic system for the synthesis of biologically active molecules.

Recent Advancement of Ullmann Condensation Coupling Reaction in the Formation of Aryl-Oxygen (C-O) Bonding by Copper-Mediated Catalyst

Transition metal-catalyzed chemical transformation of organic electrophiles and organometallic reagents belong to the most important cross coupling reaction in organic synthesis. The biaryl ether division is not only popular in natural products and synthetic pharmaceuticals but also widely found in many pesticides, polymers, and ligands. Copper catalyst has received great attention owing to the low toxicity and low cost. However, traditional Ullmann-type couplings suffer from limited substrate scopes and harsh reaction conditions. The introduction of homogeneous copper catalyst with presence of bidentate ligands over the past two decades has totally changed this situation as these ligands enable the reaction promoted in mild condition. The reaction scope has also been greatly expanded, rendering this copper-based cross-coupling attractive for both academia and industry. In this review, we will highlight the latest progress in the development of useful homogeneous copper catalyst with presence of ligand and heterogeneous copper catalyst in Ullmann type C-O cross-coupling reaction. Additionally, the application of Ullmann type C-O cross coupling reaction will be discussed.

Investigation of Novel Pesticides with Insecticidal and Antifungal Activities: Design, Synthesis and SAR Studies of Benzoylpyrimidinylurea Derivatives

In order to find pesticides with insecticidal and antifungal activities, a series of novel benzoyl pyrimidinylurea derivatives were designed and synthesized. All target compounds were identified by ¹H-NMR spectroscopy and HRMS. Insecticidal and antifungal activity of these compounds were evaluated and the structure-activity relationships (SAR) were clearly and comprehensively illustrated. Compound 7, with low toxicity to zebrafish (LC50 = 378.387 µg mL-1) showed 100% inhibition against mosquito (Culex pipiens pallens) at 0.25 µg mL-1. Both compounds 19 and 25 exhibited broad-spectrum fungicidal activity (>50% inhibitory activities against 13 phytopathogenic fungi), which were better than those of the commercial pesticide pyrimethanil (>50% inhibitory activities against eight phytopathogenic fungi). Furthermore, compounds 19 and 25 exhibited protective activity against Sclerotinia sclerotiorum on leaves of Brassica oleracea L. during in vivo experiments.

CuI nanoparticle-catalyzed synthesis of tetracyclic benzo[e]benzo[4,5]imidazo[1,2-c][1,3]thiazin-6-imine heterocycles by SNAr-type C-S, C-N bond formation from isothiocyanatobenzenes and benzimidazoles

In this paper, a simple and practical synthesis of benzo[e]benzo[4,5]imidazo[1,2-c][1,3]thiazin-6-imine tetracyclic heterocycles via a CuI nanoparticle-catalyzed intramolecular C(sp2)-S coupling reaction is presented. This strategy provides a straightforward method for synthesizing analogs of the anti-HIV drug 3,4-dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine (PD 404182). The reaction rate and yield were increased by employing CuI nanoparticles.

Diaryl ethers synthesis: nano-catalysts in carbon-oxygen cross-coupling reactions

The diaryl ether moiety is not only prevalent in a significant number of natural products and synthetic pharmaceuticals but also widely found in many pesticides, polymers, and ligands. Ullmann-type cross-coupling reactions between phenols and aryl halides are regarded as one of the most important methods for the synthesis of this important and versatile structural motif. In recent years, the use of nano-sized metal catalysts in this coupling reaction has attracted a lot of attention because of these catalysts with their high surface-to-volume ratio, high surface energy, and reactive morphology allows for rapid C-O bond formation under mild and ligand-free conditions. In this review we will highlight the power of these catalysts in Ullmann-type C-O cross-coupling reactions.

Sonochemically synthesized blue fluorescent functionalized graphene oxide as a drug delivery system

Ultrasound assisted the copper-catalyzed cross-coupling reaction to synthesis 1-(10-bromoanthracene-9-yl)-1H-imidazole-4,5-dicarboxylic acid (A-Im). The obtained product was employed to modify graphene oxide (GO) surface to produce GO-A-Im. The resulted hybrid was characterized with Scanning Electron Microscope (SEM/EDS); X-ray Diffraction spectroscopy (XRD); X-ray photoelectron spectroscopy (XPS); Fluorescence spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), and UV-Vis absorption spectroscopy. The synthesized (A-Im) moiety that was used for functionalization of GO, display a cyan emission around (496 nm), however, the GO hybrid exhibited blue photoluminescence around (403 nm). It has been proposed that the chemical attachment of the A-Im moiety onto GO surface leads to a distortion in the bandgap of the GO and the blue shift of luminescence [93 nm] was observed. Indeed the cytotoxicity properties of the synthesized hybrid were measured. The IC₅₀ value for the hybrid was 23 µg/ml. The model drug (DOX) was loaded up to 91% on the carrier, and the release profile indicated a pH-dependent discharge with more release in acidic pH. The GO-A-Im/DOX was injected to the 4T1 tumor (murine breast cancer) bearing BALB/c mice and after 10 days the tumor was disappeared.

The recent development of efficient Earth-abundant transition-metal nanocatalysts

Whereas noble metal compounds have long been central in catalysis, Earth-abundant metal-based catalysts have in the same time remained undeveloped. Yet the efficacy of Earth-abundant metal catalysts was already shown at the very beginning of the 20th century with the Fe-catalyzed Haber-Bosch process of ammonia synthesis and later in the Fischer-Tropsch reaction. Nanoscience has revolutionized the world of catalysis since it was observed that very small Au nanoparticles (NPs) and other noble metal NPs are extraordinarily efficient. Therefore the development of Earth-abundant metals NPs is more recent, but it has appeared necessary due to their "greenness". This review highlights catalysis by NPs of Earth-abundant transition metals that include Mn, Fe, Co, Ni, Cu, early transition metals (Ti, V, Cr, Zr, Nb and W) and their nanocomposites with emphasis on basic principles and literature reported during the last 5 years. A very large spectrum of catalytic reactions has been successfully disclosed, and catalysis has been examined for each metal starting with zero-valent metal NPs followed by oxides and other nanocomposites. The last section highlights the catalytic activities of bi- and trimetallic NPs. Indeed this later family is very promising and simultaneously benefits from increased stability, efficiency and selectivity, compared to monometallic NPs, due to synergistic substrate activation.

Imidazolium- and Triazine-Based Porous Organic Polymers for Heterogeneous Catalytic Conversion of CO2 into Cyclic Carbonates

CO₂ adsorption and concomitant catalytic conversion into useful chemicals are promising approaches to alleviate the energy crisis and effects of global warming. This is highly desirable for developing new types of heterogeneous catalytic materials containing CO₂ -philic groups and catalytic active sites for CO₂ chemical transformation. Here, we present an imidazolium- and triazine-based porous organic polymer with counter chloride anion (IT-POP-1). The porosity and CO₂ affinity of IT-POP-1 may be modulated at the molecular level through a facile anion-exchange strategy. Compared with the post-modified polymers with iodide and hexafluorophosphate anions, IT-POP-1 possesses the highest surface area and the best CO₂ uptake capacity with excellent adsorption selectivity over N₂ . The roles of the task-specific components such as triazine, imidazolium, hydroxyl, and counter anions in CO₂ absorption and catalytic performance were illustrated. IT-POP-1 exhibits the highest catalytic activity and excellent recyclability in solvent- and additive-free cycloaddition reaction of CO₂ with epoxides.

Formation of C–C, C–S and C–N bonds catalysed by supported copper nanoparticles

Copper nanoparticles on different supports are effective reusable catalysts for the palladium- and ligand-free coupling of aryl halides with alkynes, thiols and azoles.

The recent development of efficient Earth-abundant transition-metal nanocatalysts

This review presents the recent remarkable developments of efficient Earth-abundant transition-metal nanocatalysts.

Titanium tetrachloride-mediated synthesis of N-aryl-substituted azacycles from cyclic ethers

Five- and six-membered N-aryl-substituted azacycles were synthesized from amines and cyclic ethers under mild conditions while no expensive metal reagent was required.

Orthogonal Discrimination among Functional Groups in Ullmann-Type C-O and C-N Couplings

The copper-catalyzed arylation of nucleophiles has been established as an efficient methodology for the formation of C-C and C-heteroatom bonds. Considering the advances during the last two decades, the ligand choice plays a key role in such transformations and can strongly influence the catalytic efficiency. The applicability of these Ullmann-type coupling reactions regarding the orthogonal selectivity of different functional groups constitutes a challenging subject for current synthetic strategies. Herein, we report a useful toolkit of Cu-based catalysts for the chemoselective arylation of a wide-range of nucleophiles in competitive reactions using aryl iodides and bromides. We show in this work that the arylation of all kinds of amides can be orthogonal to that of amines (aliphatic or aromatic) and phenol derivatives. This high chemoselectivity can be governed by the use of different ligands, yielding the desired coupling products under mild conditions. The selectivity trends are maintained for electronically biased iodobenzene and bromobenzene electrophiles. Radical clock experiments discard the occurrence of radical-based mechanisms.

CsF/clinoptilolite: an efficient solid base in SNAr and copper-catalyzed Ullmann reactions

CsF/clinoptilolite was found to be an efficient solid base catalyst for both SNAr and Ullmann ether reactions. A general and efficient one-step procedure was developed for the synthesis of biaryl ethers via direct coupling of electron-deficient aryl halides to phenols using CsF/clinoptilolite. The protocol was also applied to electron-rich aryl halides by addition of a catalytic amount of copper oxide nanoparticles. Both SNAr and Ullmann reactions were rapid and provided good to excellent yields.

A comparative study of the catalytic activity of Co- and CoFe2O4-NPs in C–N and C–O bond formation: synthesis of benzimidazoles and benzoxazoles from o-haloanilides

Herein, new methods and a comparison of the results for dehalogenative intramolecular C–X bond formation using two inexpensive and efficient catalysts are reported.

tert-Butoxide mediated cascade desulfonylation/arylation/hydrolysis of cyclic sulfonyimines using diaryliodonium salts: synthesis of diaryl ether derivatives bearing a 2-aldehyde group

Cascades of cyclic sulfonyimines mediated by ^tBuOK with diaryliodonium salts has been developed, giving the diaryl ethers in good yields.

CuI nanoparticles mediated expeditious synthesis of 2-substituted benzimidazoles using molecular oxygen as the oxidant

2-Substituted benzimidazoles from o-diaminobenzenes and aldehydes using CuI nanoparticles as a heterogeneous nano-catalyst and O₂ as an oxidant were synthesised in excellent yields.

Copper/β-diketone-catalysed N-arylation of carbazoles

A copper/β-diketone-catalysedN-arylation of carbazoles with aryl iodides is developed with broad substrate applicability and moderate to good yields.

Ligand-free reusable nano copper oxide-catalyzed synthesis of 3-amino-1,4-diynes

The synthesis of 3-amino-1,4-diynes has been developed by the two-component coupling of N,N-dimethyl formamide dimethyl acetal with terminal alkynes using CuO nanoparticles as an efficient catalyst under mild reaction conditions.

Cu(0)@Al2O3/SiO2 NPs: an efficient reusable catalyst for the cross coupling reactions of aryl chlorides with amines and anilines

The C–N cross coupling reaction of aryl chlorides with various alkyl/aryl amines catalyzed by copper nanoparticles impregnated on alumina/silica support (Cu(0)@Al₂O₃/SiO₂) was investigated and the catalyst showed excellent reactivity and efficacy.

N-(1-Oxy-2-picolyl)oxalamic acids as a new type of O,O-ligands for the Cu-catalyzed N-arylation of azoles with aryl halides in water or organic solvent

A new type of chelators was identified as efficient ligands for promoting Cu-catalyzed N-arylation of azoles with applicability to different solvents.