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The transition-metal-catalyzed cyanations of aryl halides are among the most used methods for synthesizing aryl nitriles. Despite tremendous advances, cyanating an aryl halide in a facile and benig...

This paper describes the synthesis and catalytic testing of a palladium complex with a 5-membered chelating [N,O] ligand, derived from the condensation of 2,6-diisopropylphenyl aniline and maple lactone. This catalyst was active towards the Suzuki-Miyaura cross-coupling reaction, and its activity was optimised through the selection of base, solvent, catalytic loading and temperature. The optimised conditions are mild, occurring at room temperature and over a short timescale (1 h) using solvents considered to be ‘green’. A substrate scope was then carried out in which the catalyst showed good activity towards aryl bromides with electron-withdrawing groups. The catalyst was active across a broad scope of electron-donating and high-withdrawing aryl bromides with the highest activity shown for weak electron-withdrawing groups. The catalyst also showed good activity across a range of boronic acids and pinacol esters with even boronic acids featuring strong electron-withdrawing groups showing some activity. The catalyst was also a capable catalyst for the cross-coupling of aryl chlorides and phenylboronic acid. This more challenging reaction requires slightly elevated temperatures over a longer timescale but is still considered mild compared to similar examples in the literature.

Significant attention has been given in the past few years to the selective transformations of N-tosylhydrazones to various useful compounds. However, the development of enantioselective versions poses considerable challenges. Herein we report a Pd-catalyzed enantioselective three-component coupling of N-tosylhydrazone, aryl halide, and terminal alkyne under mild conditions utilizing a novel chiral sulfinamide phosphine ligand (GF-Phos), which provides a facile access to chiral diarylmethyl alkynes, which are useful synthons in organic synthesis as well as exist as the skeleton in many bioactive molecules. A pair of enantiomers of the product could be easily prepared using the same chiral ligand by simply changing the aryl substituents of the N-tosylhydrazone and aryl halide. The salient features of this reaction include the readily available starting materials, general substrate scope, high enantioselectivity, ease of scale-up, mild reaction conditions, and versatile transformations.

Density functional theory computation indicates that bridge splitting of [PtII R2 (μ-SEt2 )]2 proceeds by partial dissociation to form R2 Pta (μ-SEt2 )Ptb R2 (SEt2 ), followed by coordination of N-donor bromoarenes (L-Br) at Pta leading to release of Ptb R2 (SEt2 ), which reacts with a second molecule of L-Br, providing two molecules of PtR2 (SEt2 )(L-Br-N). For R=4-tolyl (Tol), L-Br=2,6-(pzCH2 )2 C6 H3 Br (pz=pyrazol-1-yl) and 2,6-(Me2 NCH2 )2 C6 H3 Br, subsequent oxidative addition assisted by intramolecular N-donor coordination via PtII Tol2 (L-N,Br) and reductive elimination from PtIV intermediates gives mer-PtII (L-N,C,N)Br and Tol2 . The strong σ-donor influence of Tol groups results in subtle differences in oxidative addition mechanisms when compared with related aryl halide oxidative addition to palladium(II) centres. For R=Me and L-Br=2,6-(pzCH2 )2 C6 H3 Br, a stable PtIV product, fac-PtIV Me2 {2,6-(pzCH2 )2 C6 H3 -N,C,N)Br is predicted, as reported experimentally, acting as a model for undetected and unstable PtIV Tol2 {L-N,C,N}Br undergoing facile Tol2 reductive elimination. The mechanisms reported herein enable the synthesis of PtII pincer reagents with applications in materials and bio-organometallic chemistry.

We report a catalytic method to access secondary alcohols by the coupling of aryl iodides. Either aldehydes or alcohols can be used as reaction partners, making the transformation reductive or redox-neutral, respectively. The reaction is mediated by a Ni catalyst and a 1,5-diaza-3,7-diphosphacyclooctane. This P2N2 ligand, which has previously been unrecognized in cross-coupling and related reactions, was found to avoid deleterious aryl halide reduction pathways that dominate with more traditional phosphines and NHCs. An interrupted carbonyl-Heck type mechanism is proposed to be operative, with a key 1,2-insertion step forging the new C-C bond and forming a nickel alkoxide that may be turned over by an alcohol reductant. The same catalyst was also found to enable synthesis of ketone products from either aldehydes or alcohols, demonstrating control over the oxidation state of both the starting materials and products.

The generally accepted mechanism of the Suzuki—Miyaura reaction suggests a sequential activation of the substrate (aryl halide) and the reagent (arylboronic acid) by a palladium catalyst with the formation of unsymmetric biaryl as a result of a single turnover of the catalytic cycle, i.e., it is linear from the kinetic point of view. At the same time, the use of an unconventional kinetic approach based on the analysis of the differential selectivity of the reaction, rather than the regularities of catalytic activity, indicates the inadequacy of the linear mechanism, that is consistent with the hypothesis of a nonlinear (the so-called cooperative) mechanism of catalysis, in which the product is formed as a result of the substrate and reagent activation by two different palladium-containing intermediates in two parallel catalytic cycles. The experimentally observed low kinetic orders of the Suzuki—Miyaura reaction with respect to the concentration of the palladium catalyst precursor under the ligand-free conditions of catalysis are also consistent with the cooperative mechanism and can be due to the changes in the relative amount of the catalyst in two parallel catalytic cycles and/or to the process of catalyst deactivation.

Phenols are important components of pharmaceuticals, biologically active natural products, and materials. Here, we briefly discuss recent advances in catalytic hydroxylation reactions for the synthesis of phenols, with particular attention to our recent work. H2O is proved to be an efficient hydroxide reagent in converting (hetero)aryl halides into the corresponding phenols under synergistic organophotoredox and nickel catalysis. Aryl bromides as well as less reactive aryl chlorides show high reactivity in this catalytic system. This methodology can be applied to the efficient synthesis of diverse phenols and allows the hydroxylation of multifunctional pharmaceutically relevant aryl halides.1 Introduction2 Representative Methods for Transition-Metal-Catalyzed Hydroxylation of (Hetero)Aryl Halides3 Organophotoredox/Ni Dual Catalytic Hydroxylation of Aryl Halides with Water4 Summary and Outlook

Graphical abstract Metal-catalyzed reactions play a vital part to construct a variety of pharmaceutically important scaffolds from past few decades. To carry out these reactions under mild conditions with low-cost easily available precursors, various new methodologies have been reported day by day. Sandmeyer reaction is one of these, first discovered by Sandmeyer in 1884. It is a well-known reaction mainly used for the conversion of an aryl amine to an aryl halide in the presence of Cu(I) halide via formation of diazonium salt intermediate. This reaction can be processed with or without copper catalysts for the formation of C–X (X = Cl, Br, I, etc.), C-CF3/CF2, C–CN, C–S, etc., linkages. As a result, corresponding aryl halides, trifluoromethylated compounds, aryl nitriles and aryl thioethers can be obtained which are effectively used for the construction of biologically active compounds. This review article discloses various literature reports about Sandmeyer-related transformations developed during 2000–2021 which give different ideas to synthetic chemists about further development of new and efficient protocols for Sandmeyer reaction. An updated compilation of new approaches for Sandmeyer reaction is described in this review to construct a variety of carbon-halogen, carbon-phosphorous, carbon-sulfur, carbon-boron etc. linkages.

In this paper, we report a novel magnetically separable silica coated copper nano-magnetite NHC-benzimi@Cu complex as heterogeneous catalyst for the multicomponent click reaction via Huisgen 1,3-dipolar cycloaddition reaction of alkyl or aryl halide, sodium azide and terminal alkyne, which affords various1,4-disubstituted 1,2,3-triazoles. The multistep prepared nano catalyst has been characterized by various spectroscopic methods such as FT-IR, TGA, EDX, XRD, TEM and VSM. The heterogeneous nano catalyst structures coated on the copper surface are responsible for the excellent catalyst performances in the reaction. The reusability of the catalyst makes the present protocol more fascinating from an environmental and economic point of view.

Designing of eco-friendly, low cost, and thermally stable stabilizing/supporting agents are always desired for production of catalyst systems which provide good catalytic performance in organic reactions. In this study, a novel, green, and efficient stabilizer containing chitosan/Co3O4 microspheres (CS/Co3O4) was developed. Palladium nanoparticles (Pd NPs) were then successfully immobilized on CS/Co3O4 as a heterogeneous nanocatalyst (Pd NPs/CS/Co3O4). Characterization of the designed materials were performed by FT-IR, TEM, FE-SEM, XRD, and EDS and it was determined that Pd NPs formed as approximately 20 nm. Catalytic behavior of Pd NPs/CS/Co3O4 was investigated in the production of different substituted benzonitriles via aryl halide cyanation. Catalytic studies indicate that electron-rich or poor aromatic halides were smoothly cyanated with good reaction yields by Pd NPs/CS/Co3O4 nanocatalyst by using K4[Fe(CN)6] as the cyanating agent. Moreover, it was found that Pd NPs/CS/Co3O4 nanocatalyst provided not only good reaction yields and but also good recovery/reusability for six times in the aryl halide cyanations. This paper displays that Pd NPs/CS/Co3O4 nanocatalyst has a great catalytic and recycling potential for aryl halide cyanations.

We herein disclose the first Ni-catalyzed Hiyama coupling of aryl halides with vinylsilanes. This protocol uses cheap, nontoxic, and stable vinyltrimethoxysilane as the vinyl donor, proceeds under mild and ligand-free conditions, furnishing a diverse variety of styrene derivatives in high yields with excellent functional group compatibility.

The formation of diaryl ethers is generally achieved via transition metal catalyzed etherification reactions (Ullmann, Chan–Lam, Buchwald–Hartwig) with prefunctionalized aryl halide substrates at elevated temperatures. Herein, we report a protocol for electrochemical C(sp2)–H/O–H cross-dehydrogenative coupling of phenols and tertiary anilines to synthesize diaryl ethers. The C(sp2) H/O–H coupling product can be obtained under metal- and oxidant-free conditions at room temperature in moderate to excellent yield (up to 83% yield) with high regioselectivity (>99% for para-substitution) and with a broad substrate scope (22 examples).

Biochar is a carbon-rich solid, the surface of which is covered with a high density of functional carbonyl, hydroxyl and carboxylic acid groups. In this work, palladium nanoparticles were embedded on magnetic biochar and a new reusable and environmentally-friendly catalyst was developed and applied for the promotion of Suzuki-Miyaura C-C coupling and cyanation reactions. The high-carbon (77%), low-ash content (5.8%) and the relatively high surface area (266 m(2) g(-1)) of pine tree biochar (PTB) suggested that it might be highly suitable as a catalyst substrate. The Fe3O4-Pd-biochar nanocomposite was successfully characterized using SEM, TEM, EDX, FT-IR, BET and XRD. Its catalytic role was initially evaluated using p-NO2C6H4I as a model reactant (for both types of reactions) and later for the production of biaryls and benzonitriles from a wide range of aryl halides under mild reaction conditions. Biaryls and benzonitriles were characterized using GC-MS. In the case of the Suzuki-Miyaura reaction, the optimum yield of 98% was obtained with a catalyst concentration of 0.04 mol%, microwave irradiation of 400 W, and a residence time of 5 min, using K2CO3 as the base. With respect to the cyanation reaction, dimethylformamide, Na2CO3 and 6 h were the optimum solvent, base and reaction duration, respectively. Subsequently, the nanocatalyst showed excellent catalytic activity in both reactions, achieving >88% yields in most cases, regardless of the aryl iodide or bromide used and the type of substitution.

Recently, the dynamic nature of the metal-NHC bond has been proposed and the key role of chemical evolution in changing the nature of catalytically active sites is now an emerging topic. A comparative analysis of the ketone α-arylation reaction with aryl halides, catalyzed by M/NHC complexes, was carried out in the present study and showed a fundamental difference in the behavior of the catalytic system for M = Ni and Pd. In situ evolution of Ni/NHC complexes with cleavage of the Ni-NHC bond leads to complete deactivation of catalytic systems, regardless of the nature of the aryl halide ArX (X = Cl, Br, I). However, upon Pd/NHC catalysis, the cleavage of the Pd-NHC bond causes deactivation only in the case of aryl chlorides. In the reactions of more active aryl iodides and aryl bromides, NHC-disconnected Pd species, formed as a result of the chemical transformation of Pd/NHC complexes, can provide effective catalysis in the arylation reaction under study. New catalytic systems based on Pd/NHC and Ni/NHC complexes generated in situ from stable imidazolium salts, IPr·HCl and IPr*OMe·HCl, and Pd(OAc)2 (0.1 mol%) or NiCl2Py2 (5 mol%) were developed for the selective α-arylation of methylaryl ketones (Pd-catalysis) and other ketones less prone to aldol-crotonic condensation (Ni-catalysis). The present study has shown that the different effects of the metal-NHC bond cleavage should be taken into account for the efficient choice and optimization of catalytic systems to carry out arylation reaction with various aryl halides.

Three-component cross-coupling in the system aryl halide–arylacetylene–alkene in the presence of simplest ligand-free palladium catalysts gave products of both 1+1+1-coupling and cross-dimerization of arylacetylene with alkene. The possibility of controlling the reaction selectivity has been demonstrated.

We report a facile solution-phase sonochemical route for the glucose-template mediated synthesis of Cu2O nanocrystals with well-defined sizes and shapes. This approach offers a superficial and cost-effective route for the synthesis of Cu2O nanocrystals. The formation of different nanostructures (i.e., stars, cubes, and octahedra) was tuned by varying the reaction conditions as well as the concentration of template. The morphology-controlled Cu2O nanocrystals show high activity for the external base-free Ullmann homocoupling reactions of aryl halides. 61.6% conversion of chlorobenzene was achieved over octagonal Cu2O nanocrystals with a turn-over-frequency (TOF) as high as 1696 h−1. This result demonstrates that the size and shape-dependent properties of Cu2O nanocrystals are critical to the activity of aryl halide and highlights the importance of shape engineering in the design and development of an efficient catalyst for the Ullmann reaction.

Reported here are conditions for the construction of spirocyclic piperidines from linear aryl halide precursors. These conditions employ a strongly reducing organic photoredox catalyst in combination with a trialkylamine reductant to achieve formation of aryl radical species. Regioselective cyclization followed by hydrogen-atom transfer affords a range of complex spiropiperidines. This system operates efficiently under mild conditions without the need for toxic reagents or precious metals.

A palladium-catalyzed cross-coupling reaction with aryl halide functionalities has recently emerged as a valuable tool for protein modification. Herein, a new fluorogenic modification methodology for proteins, with genetically encoded fluorosulfate-l-tyrosine, which exhibits high efficiency and biocompatibility in bacterial cells as well as in aqueous medium, is described. Furthermore, the cross-coupling of 4-cyanophenylboronic acid on green fluorescent protein was shown to possess a unique fluorogenic property, which could open up the possibility of a responsive "off/on" switch with great potential to enable spectroscopic imaging of proteins with minimal background noise. Taken together, a convenient and efficient catalytic system has been developed that may provide broad utilities in protein visualization and live-cell imaging.

The copper-catalyzed arylation of unsaturated nitrogen heterocycles, known as the Ullmann–Goldberg coupling, is a valuable transformation for medicinal chemists, providing a modular disconnection for the rapid diversification of heteroaromatic cores. The utility of the coupling, however, has established limitations arising from a high-barrier copper oxidative addition step, which often necessitates the use of electron-rich ligands, elevated temperatures, and/or activated aryl electrophiles. Herein, we present an alternative aryl halide activation strategy, in which the critical oxidative addition (OA) mechanism has been replaced by a halogen abstraction–radical capture (HARC) sequence that allows the generation of the same Cu(III)-aryl intermediate albeit via a photoredox pathway. This alternative mechanistic paradigm decouples the bond-breaking and bond-forming steps of the catalytic cycle to enable the use of many previously inert aryl bromides. Overall, this mechanism allows access to both traditional C–N adducts at room temperature as well as a large range of previously inaccessible Ullmann–Goldberg coupling products including sterically demanding ortho-substituted heteroarenes.

In this work, Pd nanoparticles (Pd-NPs) were decorated on modified magnetic nanoparticles (MNPs) and used as an efficient and recyclable catalyst for the Suzuki cross-coupling reaction of aryl halides with phenylboronic acid (PhB(OH)2) in a green solvent. The prepared nanocomposite was characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transforms infrared spectroscopy, X-ray powder diffraction, thermogravimetric analysis/differential thermal analysis, and vibrating sample magnetometry. All analyses confirmed the successful modification of MNPs and immobilization of Pd on modified MNPs. This catalyst exhibited superior catalytic activity and stability in the suzuki cross-coupling reaction of PhB(OH)2 and aryl halide derivatives. This protocol includes some advantages, such as magnetically reusability of the catalyst, mild experimental conditions, green solvent, excellent yields of the product (52–98%), and short reaction times (4–33 min). The catalyst could be reused for six successive runs without any significant loss of its efficiency.

The monoarylation of acetone is a powerful transformation, but is typically performed at temperatures significantly in excess of its boiling point. Conditions described for performing the reaction at ambient temperatures led to significant dehalogenation when applied to a complex aryl halide. We describe our attempts to overcome both issues in the context of our drug-discovery program.

A new free radical/palladium cooperative catalyzed formylation of aryl halides with glyoxylic acid as the formyl source under oxygen conditions has been developed. Various aromatic and heteroaromatic aldehydes were produced in medium to good yields.

A photocatalytic system for the dearomative hydroarylation of benzene derivatives has been developed. Using a combination of an organic photoredox catalyst and an amine reductant, this process operates through a reductive radical-polar crossover mechanism where aryl halide reduction triggers a regioselective radical cyclization event, followed by anion formation and quenching to produce a range of complex spirocyclic cyclohexadienes. This light-driven protocol functions at room temperature in a green solvent system (aq. MeCN) without the need for precious metal-based catalysts or reagents or the generation of stoichiometric metal byproducts.

A new Schiff base catalyst (Pd(II) chemically mounted on the cellulose nanocrystals surface (CNC-APTES-IS-Pd) was developed for Ulmann and Suzuki cross-coupling reactions. The catalyst was applied for Ulmann reaction using s series of aryl halide and phenol derivatives in DMSO and preparation of biaryls via Suzuki C-C reactions between aryl halides and phenyl boronic acid. The Catalyst was characterized by FT-IR, XRD, SEM, ICP-AES and TGA techniques. The catalyst demonstrated high reaction efficiency with more than 90% reaction yield. The catalyst indicated good performance after several times recovery and reuse.

Palladium-catalyzed alkene-directed cross-coupling of aryl iodide with another aryl halide through C-H arylation opens a unique avenue for unsymmetrical biaryl-derived molecules. However, homo-coupling of aryl iodides often erodes the overall synthetic efficiency. Reported herein is a highly chemoselective Pd0 -catalyzed alkyne-directed cross-coupling of aryl iodides with bromophenols, which was subsequently followed by phenol dearomatization to furnish a very attractive [2+2+1] spiroannulation. Notably, possible homo-coupling of aryl iodides was not observed at all. Mechanistic studies indicated that a five-membered aryl/vinyl palladacycle most likely accounts for promoting the key step of biaryl cross-coupling.

The combination of metal- and biocatalysis is a challenging but forward-looking topic in synthetic chemistry. The unique selectivity of enzymes paired with the broad range of applications of chemical catalysts enables an undreamed-of number of novel processes. Herein, we describe the application of immobilized phenolic acid decarboxylase (PAD) for the decarboxylation of para-coumaric acid and subsequent Pd-catalyzed Heck cross-coupling with an aryl halide in a fully integrated two-step continuous flow process to synthesize (E)-4-hydroxy-stilbene. The application of a choline chloride-based deep eutectic solvent (DES) proved to be crucial to overcome the problem of solvent compatibility and enabled an increase in substrate concentration (from 5 mM in buffer to 20 mM in DES) as well as a process with a homogeneous starting solution. The two-step process was successfully operated for more than 16 h in continuous flow and full conversion was achieved. The results underline the usefulness of DES to overcome compatibility problems in tandem-catalytic processes. The system benefits from its simplicity due to increased substrate solubility, the possibility to conduct both reactions at their optimal temperatures and the elimination of isolating the reaction intermediate, which is prone to polymerization.

Ni 2,2’–bipyridine (bpy) complexes are commonly employed photoredox catalysts of bond-forming reactions in organic chemistry. However, the mechanisms by which they operate are still under investigation. One potential mode of catalysis is via entry into Ni(I)/Ni(III) cycles, which can be made possible by light-induced, excited state Ni(II)–C bond homolysis. Here we report experimental and computational analyses of a library of Ni(II)-bpy aryl halide complexes, Ni(Rbpy)(R′Ph)Cl (R = MeO, t-Bu, H, MeOOC; R′ = CH3, H, OMe, F, CF3), to illuminate the mechanism of excited state bond homolysis. At given excitation wavelengths, photochemical homolysis rates span two orders of magnitude across these structures and correlate linearly with Hammett parameters of both bpy and aryl ligands, reflecting structural control over key metal-to-ligand charge transfer (MLCT) and ligand-to-metal charge transfer (LMCT) excited state potential energy surfaces (PESs). Temperature- and wavelength-dependent investigations reveal moderate excited state barriers (ΔH‡ ~4 kcal mol-1) and a minimum energy excitation threshold (~55 kcal mol-1, 525 nm), respectively. Correlations to electronic structure calculations further support a mechanism in which repulsive triplet excited state PESs featuring a critical aryl-to-Ni LMCT lead to bond rupture. Structural control over excited state PESs provides a rational approach to utilize photonic energy and leverage excited state bond homolysis processes in synthetic chemistry.

Photoredox nickel catalysis has emerged as a powerful strategy for cross-coupling reactions. Although the involvement of paramagnetic Ni(I)/Ni(III) species as active intermediates in the catalytic cycle has been proposed, a thorough spectroscopic investigation of these species is lacking. Herein, we report the tridentate pyridinophane ligands RN3 that allow for detailed mechanistic studies of the photocatalytic C–O coupling reaction. The derived (RN3)Ni complexes are active catalysts under mild conditions and without an additional photocatalyst. We also provide direct evidence for the key steps involving paramagnetic Ni species in the proposed catalytic cycle: the oxidative addition of an aryl halide to a Ni(I) species, the ligand exchange/transmetalation at a Ni(III) center, and the C–O reductive elimination from a Ni(III) species. Overall, the present work suggests the RN3 ligands are a practical platform for mechanistic studies of Ni-catalyzed reactions and for the development of new catalytic applications.

An efficient nickel-catalyzed regioselective hydroarylation of 1,3-dienes with aryl halides and a silane has been developed, affording a range of allylic arenes in good to excellent yields under mild conditions. This method exhibits broad substrate scope, and excellent functional group tolerance. Late-stage modification of complex architectures was demonstrated.

A highly regioselective Ni-catalyzed electrochemical reductive relay cross-coupling between an aryl halide and an alkyl halide has been developed in an undivided cell. Various functional groups are tolerated under these mild reaction conditions, which provides an alternative approach for the synthesis of 1,1-diarylalkanes.

A series of new monoligated arylpalladacyclic complexes with amide, urea, and carbamate frameworks have been developed and were found to be highly active for Suzuki–Miyaura cross-couplings. These palladacycle precatalysts are derived from simple, inexpensive starting materials and are air- and moisture-stable. The most active congeners among those tested are the urea-based palladacycles, which in conjunction with a tBu3P ligand induce high conversions for a range of aryl halide and boronate coupling partners. Notably, aryl chlorides are viable coupling partners even under relatively mild conditions at short reaction times (e.g., 1 h at 60 °C). One of the best catalysts described here exhibits improved turnover frequency for a particularly difficult coupling reaction involving an aryl chloride and a sterically congested boronic ester.

A practically convenient protocol has been developed to convert a mixture of an aldehyde, aryl halide, and the Bestmann-Ohira reagent into disubstituted acetylene via a successive addition of base (Cs2CO3) and a Pd(II) catalyst, allowing sufficient time after addition of each of these reagents for the tandem processes (Seyferth-Gilbert homologation and Sonogashira coupling) to occur. Notably, for the latter reaction, no copper catalyst was required.

GSK2981278A (1) is a RORγ inverse agonist used as a potential topical nonsteroidal therapy for psoriasis. New synthesis of 1 was developed based on a SNAr reaction of (tetrahydro-2H-pyran-4-yl)methanol with an aryl halide intermediate, prepared from 2-halobenzoic acids. The dianion underwent in situ N,O-bis-isobutylation, followed by a reduction to provide 1. The new route eliminated a genotoxic tosylate of (tetrahydro-2H-pyran-4-yl)methanol and a difficult reductive amination from the original synthesis starting from methyl salicylate. A primary version of the route has been scaled up to deliver 125 kg of 1. However, the heating of a strong base in DMSO for an extended period during the bis-alkylation was found to be a safety concern for manufacturing. A safer and greener process was then developed utilizing a facile N,O-bis-alkylation, which was conducted under phase transfer conditions with mild bases such as potassium carbonate and in green solvents such as water. The concise four stage sequence from ...

A rare reductive coupling of nitro compounds with organohalides has been realized. The reaction is initiated by a partial reduction of the nitro group to a nitrenoid intermediate. Therefore, not only aromatic but also aliphatic nitro compounds are efficiently transformed into monoalkylated amines, with organohalides as the alkylating agent. Given the innate reactivity of the nitrenoid, a catalyst is not required, resulting in a high tolerance for aryl halide substituents in both starting materials.

The aryl halide-arylacetylene-arylboronic acid three-component coupling in the presence of a Pd catalyst containing no organic ligands is described. The reaction routes that take place in the reaction system are shown to include the consecutive carbopalladation of two arylacetylene molecules, leading to unsaturated polyaromatic compounds. The possibility of controlling the alternative reaction routes is demonstrated.

This paper presents the results of a kinetic study on the step of activation of aryl iodides and aryl bromides under conditions of ligand-free catalysis in the direct arylation of indole at a C–H bond performed using an analysis of the integral kinetic curves of consumption of the competing aryl halides. In the course of an experiment under the conditions of competition between a pair of aryl halides having different reactivity, an acceleration in the consumption of a less active substrate was observed, which coincided in time with the almost complete consumption of a more active one. The experimental data unambiguously indicated a rapid character of the stage of oxidative addition with the participation of not only reactive aryl iodides but also nonactivated aryl bromides.

A combination of CuI with oxalic diamide is a powerful catalytic system for cross-coupling reaction of thiols with aryl bromides and chlorides. It is important to note that unactivated aryl...

The Sonogashira cross coupling reaction is an applied method for preparation of diarylethyne compounds from readily available aryl halide derivatives and phenyl acetylene. The coupling reaction using nickel complex of N,N′-Bis(2-hydroxyethyl)ethylenediamine onto core shell graphene oxide (GO@SiO2-BHED-Ni) as a catalyst was studied in this research. This heterogonous catalyst showed good thermal stability, highly efficiency and recyclability in the reaction. Moreover, the catalyst is simply separated and can be reused several times without significant loss of catalytic activity. A wide range of aryl halides was coupled successfully under palladium and phosphine free conditions. The use of this catalyst led to the formation of substituted aromatic alkynes in excellent yields and short reaction times.

We report the synthesis of Fe-NCN pincer complex as homogenous catalyst and its composite by immobilizing the complex on amino functionalized graphene oxide as a heterogeneous catalyst for Suzuki coupling reactions. Both the complex and the composite were employed in catalyzing the Suzuki-Miyaura cross-coupling reaction between the aryl halide and phenyl boronic acid in acetonitrile solvent media with Cs2CO3 as a base. Effect of substitution over aryl halide was also investigated. Immobilization of the pincer complex had advantageous recovery and reuse of the catalyst as compared to its homogenous analog with no significant decrease in the catalytic efficiency. Keywords: Suzuki-Miyaura cross-coupling, NCN pincer, Amino functionalized graphene oxide, Catalysis, Biaryls

Transition metal copper (II) Schiff base composite (Cu NH2 GO) was synthesized using functionalized graphene oxide with (3-aminopropyl) methoxysilane (APTMS). X-ray diffraction, FTIR spectroscopy and thermogravimetric analyses ascertained the incorporation of the copper (II) Schiff base on the functionalized graphene oxide. Scanning electron microscopy and TEM evidences further confirmed the surface morphology of the composite. Catalytic activity study indicated that the synthesized Cu NH2 GO was active for cross-coupling of aryl halide with phenylboronic acid. Above 84% (4-Iodobenzonitrile) biphenyl conversion could be achieved using Cu NH2 GO catalyst in the C C coupling reaction.

Pd-encapsulated porous carbon materials (Pd-PCMs) were prepared from the coupling polymerization of an aryl halide and aryl alkyne under mild conditions. Combining its porous microstructure and encapsulated Pd nanoparticles, Pd-PCMs with high sulfur loading reach a capacity of 920 mA h g-1 after 200 cycles at 0.3C.

Carbon-carbon cross-coupling reactions are essential synthetic tools for synthesizing polymers, natural products, agrochemicals, and pharmaceuticals. Therefore, new catalysts that function with greater efficiency and functional group tolerance are being researched. We have prepared new ferrocenylimine monodentate N and P donor ligands and N^N and N^P bidentate chelating ligands (L1 to L4) employed in stabilizing palladium ions for application in Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions. The ferrocenylimine ligands were successfully synthesized by Schiff base condensation reactions of acetyl ferrocene with hydrazine monohydrate to afford ferrocenyl hydrazone (L1). Ligand L1 was further treated with aldehydes to give ferrocenyl(2-diphenylphosphino)imine (L3) and ferrocenyl(pyridyl)imine (L3), while phosphination of L1 with chlorodiphenylphosphine afforded L2. The ligands were used to prepare new palladium(II) complexes (C1 to C4) by complexation with [PdCl2(MeCN)2]. All the ligands and complexes were fully characterized using standard spectroscopic and analytical techniques, including 1H NMR and 13C NMR spectroscopy, FT-IR spectroscopy, mass spectrometry and elemental analysis. The complexes (C1 to C4) were tested for efficacies in catalyzing Mizoroki-Heck and Suzuki-Miyaura C-C cross-coupling reactions and proved to be suitable catalyst precursors. Ferrocenyl(2-diphenylphosphine)imino and ferrocenyl-methyl hydrazone palladium(II) complexes C2 and C3 showed the best activities at TONs of up to 201. The ferrocenyl palladium(II) (pre)catalysts demonstrated moderate activity in Mizoroki-Heck reactions involving substrates with substituents on the olefin and aryl halide (including 4-Cl, 4-CH3, -CO2Me and -CO2Et). Density Functional Theory was used to study the mechanism of the Mizoroki-Heck cross-coupling reactions and have led to confirmation of the widely accepted catalytic cycle. Catalyst precursors (C1 to C4) also displayed good activity and selectivity in Suzuki-Miyaura cross-coupling reactions, at 0.5 mol% catalyst loading, with good tolerance to functional groups present on the aryl halide and boronic acid substrates (such as 4-Cl, 4-CHO, 4-COOH, 3-NO2, 3,5-dimethoxy and 4-CH3).