Copper supported silica-based nanocatalysts for CuAAC and cross-coupling reactions

Recent advances in Cu/SiO2-based heterogeneous catalysts for click reaction, C–N, C–S, and C–O coupling reactions are reviewed and summarized.

Safe, Scalable, Inexpensive, and Mild Nickel-Catalyzed Migita-Like C-S Cross-Couplings in Recyclable Water

A new approach to C-S couplings is reported that relies on nickel catalysis under mild conditions, enabled by micellar catalysis in recyclable water as the reaction medium. The protocol tolerates a wide range of heteroaromatic halides and thiols, including alkyl and heteroaryl thiols, leading to a variety of thioethers in good isolated yields. The method is scalable, results in low residual metal in the products, and is applicable to syntheses of targets in the pharmaceutical area. The procedure also features an associated low E Factor, suggesting a far more attractive entry than is otherwise currently available, especially those based on unsustainable loadings of Pd catalysts.

Cerium catalyst promoted C-S cross-coupling: synthesis of thioethers, dapsone and RN-18 precursors

In this work, we present a novel, efficient and green methodology for the synthesis of thioethers by the C-S cross-coupling reaction with the assistance of [Ce(l-Pro)2]2Ox as a heterogeneous catalyst in good to excellent yields. A scale-up of the protocol was explored using an unpublished methodology for the synthesis of a dapsone-precursor, which proved to be very effective over a short time. The catalyst [Ce(l-Pro)2]2Ox was recovered and it was shown to be effective for five more reaction cycles.

Task-Specific Properties and Prospects of Ionic Liquids in Cross-Coupling Reactions

Ionic liquids (ILs) are considered as highly useful materials for potential diverse uses such as greener and more convenient alternatives to volatile organic solvents, reagents, additives, ligands and co-solvents. Thermal stability, negligible vapor pressure and high polarity with ionic environments have possibly conferred some unique physico-chemical properties and a wider electrochemical window on ILs. More importantly, these properties are tuneable, depending on variations in alkyl chains and counter-anions. On the other hand, various transition-metal-catalyzed cross-coupling reactions constitute an important backbone of contemporary organic synthesis. A vast number of C-C and C-heteroatom cross-coupling reactions are reported in the presence of ILs, often showing better performance. The influence of IL on the action of a given catalyst or on the course of a reaction can be relatively complex, and is not understood well enough to be able to draw succinct conclusions. However, there are a few reports in the literature that help understand the role of actual and active catalytic species stabilized in an IL environment. Stabilization, which can be either helpful or detrimental to catalysis depends on specific circumstances. This review article is aimed primarily at summarizing the various applications of ILs during the past decade, focusing as far as possible on the task-specific properties of ILs in transition-metal-catalyzed C-C and C-heteroatom cross-coupling reactions. Several successful achievements and noteworthy progress in this field of research leads to the sensible conclusion that future prospects in this field of research are not only bright but promise new horizons.

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.

An efficient copper catalyzed 3D mesoporous aluminosilicate for the synthesis of dibenzodiazonines in the Ullmann cross-coupling reaction

CuO distribution in the aluminosilicate framework and acidic sites play a multifunctional role in the reaction. 13H-Dibenzo[1,4]diazonine has been synthesized by using a 6 wt% CuO/Al-KIT-6 catalyst using ethanol as solvent.

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C-S cross-coupling reaction

The present work demonstrates the C–S cross-coupling reaction between aryl halides and thiols using nickel nanoparticles (Ni NPs) supported on reduced graphene oxide (Ni/RGO) as a heterogeneous catalyst. It is observed that the uniformly dispersed Ni NPs supported on RGO could exhibit excellent catalytic activity in C–S cross-coupling reactions and the catalytic application is generalized with diverse coupling partners. Although the electron-rich planar RGO surface helps in stabilizing the agglomeration-free Ni NPs, the catalytic process is found to occur involving Ni(II) species and the recovered catalyst containing both Ni(0)/Ni(II) species is equally efficient in recycle runs. A correlation of loading of Ni species, size of NPs and the intermediate Ni-related heterostructures formed during the catalytic process has been established for the first time, and found to be best in the C–S cross-coupling reaction for Ni(0) and Ni(II) NPs of the average sizes 11–12 nm and 4 nm, respectively.

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.

A magnetically recyclable iron oxide-supported copper oxide nanocatalyst (Fe3O4–CuO) for one-pot synthesis of S-aryl dithiocarbamates under solvent-free conditions

A convenient preparation of S-aryl dithiocarbamates from amine, carbon disulfide and aryl iodide was developed by using the Fe₃O₄–CuO nanocatalyst under solvent free conditions.

Sulfides Synthesis: Nanocatalysts in C–S Cross-Coupling Reactions

The C–S cross-coupling reaction of aryl halides with thiols or sulfur sources is a key and valuable synthetic transformation in chemistry and medicine as well as in biology, and the development of novel efficient synthetic protocols for the synthesis of the corresponding products (sulfides) is highly desired. Among a wide range of catalysts used in C–S coupling reactions, metallic nanocatalysts have attracted notable interest. Herein, we summarize recent breakthroughs in the arena of metal nanocatalysts employed in C–S cross-coupling reactions with the goal of stimulating further progress in this field. This review is divided into three main sections according to the nature of the metal nanocatalysts discussed. The first section focuses on naked or purely metallic catalysts in nano-size, such as Cu, Pd, Ni, and In. The second section focuses on the role of Fe3O4 magnetic nanoparticles and mesoporous silica nanomaterials, such as MCM-41 and SBA-15, as catalyst supports. Finally, the third section focuses on the catalytic activities of copper ferrite nanoparticles in C–S cross-coupling reactions. Additionally, the recovery and reusability of the nanocatalyst, which are very important from commercial and economical points of view, are comprehensively discussed in this review.

DMSO/iodine-catalyzed oxidative C–Se/C–S bond formation: a regioselective synthesis of unsymmetrical chalcogenides with nitrogen- or oxygen-containing arenes

A convenient metal-free and solvent-free iodine-catalyzed regioselective greener protocol to access different types of unsymmetrical chalcogenides with nitrogen- or oxygen-containing arenes through oxidative C–Se/C–S formation via direct C(sp²)–H bond activation was developed.

An efficient heterogeneous catalyst (CuO@ARF) for on-water C-S coupling reaction: an application to the synthesis of phenothiazine structural scaffold

Background

Aryl sulfides have significant importance from biological and pharmaceutical aspects. Transition metal-catalyzed carbon-sulfur cross-coupling reaction represents an important tool for the synthesis of sulfides. Among various transition metals, copper salts or oxides have found vast applicability.

Results

A simple procedure for the preparation of poly-ionic amberlite resins embedded with copper oxide nanoparticles (CuO NPs) (denoted as CuO@ARF) has been developed, characterized, and employed for the first time as a heterogeneous ligand-free catalyst for ‘on-water’ C-S cross-coupling reaction. The NPs of CuO with an average size (approximately 2.6 nm), as determined from high resolution transmission electron microscopy (HRTEM) images, are found to be a potentially active, chemoselective, and recyclable catalyst for the preparation of symmetrical and unsymmetrical aryl sulfides. Recycling of the catalyst was performed successfully for five consecutive runs, and apparently no leaching was observed in a hot filtration test. Excellent chemoselectivity between iodo- and bromo-arene has been exploited in step-wise C-S and C-N couplings to synthesize bioactive heterocyclic scaffold phenothiazine.

Conclusions

An efficient method is established for the C-S cross-coupling reaction using heterogeneous catalyst CuO@ARF under ligand-free on-water condition. The catalyst is highly chemoselective among different aryl halides, which has been demonstrated in the synthesis heterocyclic scaffold phenothiazine. Furthermore, it is recyclable for five consecutive runs examined.Graphical abstract

An efficient d-glucosamine-based copper catalyst for C–X couplings and its application in the synthesis of nilotinib intermediate

d-Glucosamine has been studied for C–N and C–S bond formations via cross-coupling reactions of nitrogen and sulfur nucleophiles with both aryl iodides and bromides.

Metal complexes with bis(2-pyridyl)diselenoethers: structural chemistry and catalysis

Bis(2-pyridyl)diselenoethers are versatile ligands for the synthesis of transition metal complexes. Some products show remarkable catalytic activities.

Copper catalysed Ullmann type chemistry: from mechanistic aspects to modern development

Cu-catalysed arylation reactions devoted to the formation of C-C and C-heteroatom bonds (Ullmann-type couplings) have acquired great importance in the last decade. This review discusses the history and development of coupling reactions between aryl halides and various classes of nucleophiles, focusing mostly on the different mechanisms proposed through the years. Selected mechanistic investigations are treated more in depth than others. For example, evidence in favour or against radical mechanisms is discussed. Cu(I) and Cu(III) complexes involved in the Ullmann reaction and N/O selectivity in aminoalcohol arylation are discussed. A separate section has been dedicated to the synthesis of heterocyclic rings through intramolecular couplings. Finally, recent developments in green chemistry for these reactions, such as reactions in aqueous media and heterogeneous catalysis, have also been reviewed.

Fabrication of magnetic amino-functionalized nanoparticles for S-arylation of heterocyclic thiols

The aminosilane coupling agent and polyethylene imine-600 were loaded onto magnetic nanoparticles to obtain magnetic nanoligands (MNLs) A, B, C and D.