Catalyzed Suzuki Miyaura Research Articles

Suzuki-Miyaura coupling reaction: Blue-yellow emitting AIE active dyes for organic electronics

A series of eight novel donor‒acceptor (D─A) based 2,3-di(thiophen-2-yl)quinoxaline derivatives 2–9 were prepared by modulating donor species on quinoxaline core with Palladium catalyzed Suzuki–Miyaura ‘C–C bond’ coupling reaction. The synthesized molecules were fully characterized and studied for impact of D–A interaction on opto-electrochemical properties. Absorption spectra of 2–9 display intramolecular charge transfer (ICT) transitions in the range of 388–414 nm. Dyes shows positive solvatochromism and emit in blue‒yellow region with emission maxima 444−550 nm on excitation at their respective ICT maxima in toluene, chloroform, DCM, DMSO and neat solid film. Further, solid state emission was studied for aggregation‒induced emission (AIE) effect in THF–water system due to the nanoparticles formation, as confirmed by FEG‒SEM technique. The HOMO and LUMO energy level for compounds 2–9 were measured by cyclic voltammetry and found in the range of −5.15 to −5.94 eV and −2.81 to −3.39 eV. Theoretical studies of molecules were also carried out by using DFT and TD‒DFT calculations. The comparable HOMO and LUMO energy levels with reported ambipolar materials and efficient solid-state emission make synthesized compounds potential candidate for solid state emissive, ambipolar charge transporting materials in organic electronics.

Bio‐Inspired Cu/Pd Bimetallic Catalysts Facilitating One‐Pot Relay Catalysis of Homo‐Couplings of Arylboronic Acids

ABSTRACTInspired by the multienzymatic relay catalysis in nature, herein, we reported a pioneering bio‐inspired Cu/Pd bimetallic composite microspheres (Cu/CMC@Pd/C) as a simple and efficient relay catalyst for the homo‐coupling of arylboronic acids. In this composite, Pd/C was encapsulated by Cu(II)‐crosslinking carboxymethyl cellulose (Cu/CMC). Cu/CMC@Pd/C microspheres were easily achieved by adding a mixture solution of Pd/C and carboxymethyl cellulose into a Cu(II) solution through an ion exchange reaction between carboxylate groups of CMC and Cu(II) ions. The morphology and composition of the as‐prepared Cu/CMC@Pd/C microspheres were well characterized using various analytical tools such as FT‐IR, XRD, XPS, SEM, TEM, elemental mapping, EDS, and ICP‐AES. The analysis indicated that the composite microspheres have a porous structure and Pd/C is uniformly distributed within the interior of the composite microspheres. The porous structure facilitates mass transfer of the substrate and increases the contact area of the catalyst, thus improving reaction efficiency. The performance of Cu/CMC@Pd/C microspheres was assessed in the homo‐coupling of arylboronic acid for the synthesis of symmetric biaryl without the need for an aryl halide as a partner. This process mimics a multienzyme catalysis through a relay Cu(I)‐catalyzed halogenation of one portion of arylboronic acid and a Pd(0)‐catalyzed Suzuki–Miyaura cross‐coupling between the in situ generated aryl halide and another portion of arylboronic acid. The results showed that this bio‐inspired Cu/CMC@Pd/C has excellent relay catalytic activity with tolerance of broad functional groups, producing the desired symmetrical biaryls in excellent yields within a short reaction time under mild conditions. Moreover, the catalyst can be easily recovered through simple filtration and still has good catalytic activity after six cycles. Consequently, this innovative pseudo‐homogeneous Cu/Pd relay catalyst emerges as a convenient and efficient alternative for the synthesis of asymmetric biaryls.

New multiple-layered 3D polymers showing aggregation-induced emission and polarization.

An exceptional achiral and chiral multilayer 3D polymer has been created and controlled by uniform and distinct aromatic chromophore units that are multiply sandwiched by naphthyl berths. In order to put together this assembly, it was necessary to search for new catalytic Suzuki-Miyaura polycouplings among various catalytic systems, monomers, and catalysts. Gel Permeation Chromatography (GPC) was able to verify the presence of many framework layers. The resulting achiral and chiral polymers displayed notable optical characteristic.

Mechanochemical Synthesis of PdO2 Nanoparticles Immobilized over Silica Gel for Catalytic Suzuki-Miyaura Cross-Coupling Reactions Leading to the C-3 Modification of 1H-Indazole with Phenylboronic Acids.

The C-3 modification of 1H-indazole has produced active pharmaceuticals for the treatment of cancer and HIV. But, so far, this transformation has seemed less available, due to the lack of efficient C-C bond formation at the less reactive C-3 position. In this work, a series of silica gel-supported PdO2 nanoparticles of 25-66 nm size were prepared by ball milling silica gel with divalent palladium precursors, and then employed as catalysts for the Suzuki-Miyaura cross-coupling of 1H-indazole derivative with phenylboronic acid. All the synthesized catalysts showed much higher cross-coupling yields than their palladium precursors, and could also be reused three times without losing high activity and selectivity in a toluene/water/ethanol mixed solvent. Although the palladium precursors showed an order of activity of PdCl2(dppf, 1,1'-bis(diphenylphosphino)ferrocene) > PdCl2(dtbpf, 1,1'-bis(di-tert-butylphosphino)ferrocene) > Pd(OAc, acetate)2, the synthesized catalysts showed an order of C1 (from Pd(OAc)2) > C3 (from PdCl2(dtbpf)) > C2 (from PdCl2(dppf)), which conformed to the orders of BET (Brunauer-Emmett-Teller) surface areas and acidities of these catalysts. Notably, the most inexpensive Pd(OAc)2 can be used as a palladium precursor for the synthesis of the best catalyst through simple ball milling. This work provides a highly active and inexpensive series of catalysts for C-3 modification of 1H-indazole, which are significant for the large-scale production of 1H-indazole-based pharmaceuticals.

Synthesis of the chelated axially chiral 1,2,3-Triazol-5-ylidene-Pd(II), Ni(II) and Ru(II) complexes and exploration of Bis-MIC-Pd(II) catalyst's application in coupling reaction

A series of chelated (R)-binaphthyl-2,2-diamine (BINAM) based chiral mesoionic Pd(II), Ni(II) and Ru(II) complexes, including three chelated bis-1,2,3-triazol-5-ylidene Pd(II) complexes, one chelated bis-1,2,3-triazol-5-ylidene Ni(II) complex and one chelated mono-1,2,3-triazol-5-ylidene Ru(II) complex, have been developed through either direct metalation (Ni(II) complex) or silver(I) transmetallation (Pd(II) and Ru(II) complexes) methods. These MIC-Pd(II), Ni(II) and Ru(II) complexes have been fully characterized by NMR, ESI-MS data, in which, the structures of (R)-5a, (R)-7, and (R)-9 have been further determined by X-ray diffraction studies of their single crystals. The catalytic activities of the chiral bis-MIC-Pd(II) complexes were explored in Pd(II)-catalyzed Suzuki–Miyaura coupling reaction, in which, bisaryl coupling products could be synthesized in good to excellent yields from the reactions of various aryl boronic acids with aryl iodides. Asymmetric coupling reaction was also tested, but no enantioselectivity was obtained. Scale–up reaction and mercury poisoning experiment were then performed. The catalytic activity of (R)-5a was partly inhibited by a large excess of elemental mercury, indicating the presence of heterogeneous Pd nanoparticles in the reaction mixture.

Nickel(II) Thiocyanate Complex as a Catalyst for Cross-Coupling Reactions

AbstractA nickel thiocyanate complex was prepared by the reaction of Ni(NCS)2 with (2S,3S)-2,3-bis(diphenylphosphino)butane (Chiraphos) by following a method reported in the literature. The resulting nickel complex was found to be active in the polymerization reactions of 1,4-dihalobenzenes and 2-halo-3-hexylthiophenes, leading to poly-1,4-phenylenes and poly(3-hexylthiophene-2,5-diyl), respectively. The polymerization in the presence of similar catalysts containing other ligands, such as 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, or N-heterocyclic carbenes, also proceeded in a similar manner. Ni(NCS)2 complexes also successfully catalyzed Suzuki–Miyaura couplings and Buchwald–Hartwig aminations to afford the corresponding biaryls and arylamines, respectively.

Desymmetrization of Vicinal Bis(boronic) Esters by Enantioselective Suzuki-Miyaura Cross-Coupling Reaction.

The development of an enantioselective catalytic Suzuki-Miyaura reaction that applies to meso 1,2-diborylcycloalkanes is described. This reaction provides a modular route to enantiomerically enriched substituted carbocycles and heterocycles that retain a synthetically versatile boronic ester. With appropriately constructed substrates, compounds bearing additional stereogenic centers and fully substituted carbon atoms can be generated in a straightforward fashion. Preliminary mechanistic experiments suggest that substrate activation arises from the cooperative effect of vicinal boronic esters during the transmetalation step.

Role of Intralayer Hydrogen Bonding in the Fast Crystallization of the Hydrazone-Linked Nanoporous Covalent Organic Framework for Catalytic Suzuki–Miyaura Cross-Coupling Reactions

Covalent organic frameworks (COFs) are the emerging smart materials that can be designed and synthesized by tuning their structural diversity and topology for various applications. Despite vast advancements in the design of COFs, the synthetic methodologies to construct COFs are always a significant challenge. Herein, we demonstrate a fast crystallization in hydrazone-based Bth-Tp-COF, synthesized via a Schiff-base reaction between benzene-1,3,5-tricarbohydrazide (Bth) and triformylphloroglucinol (Tp) linkers under stirred conditions. The growth of the COF was typically completed in 30 min and likely driven by intra- and interlayer hydrogen bonding in COF layers, leading to the fast crystallization. Here, the intralayer hydrogen bonding prevented in-plane bond rotation, while the interlayer hydrogen bonding provided rigidity to the COF layers favoring the antiparallel stacking model. The synthesized Bth-Tp-COF was found to be highly stable in harsh chemicals such as 12 M HCl, 12 M NaOH, TFA, and water for 5 days. Moreover, when we doped palladium (Pd) in Bth-Tp-COF, the resulting Pd/Bth-Tp-COF was found to be a highly efficient heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction that completed in a quick reaction time of only 20 min with excellent yields. In addition, Pd/Bth-Tp-COF displayed high activity in the recycling experiment with a slight decrease in its crystallinity up to five catalytic cycles. The fast crystallization and metal doping strategy in COFs open up several opportunities to develop excellent heterogeneous catalysts for various chemical transformations.

Micelle-Derived Palladium Nanoparticles for Suzuki–Miyaura Coupling Reactions in Water at Room Temperature

Despite the wide utility of colloidal palladium (Pd) nanoparticle (NP)-catalyzed Suzuki–Miyaura cross-coupling reactions in laboratory and industrial synthesis, the easy construction of colloidal Pd NPs and the detailed role of surfactants remain the focus of attention. Here, we present a simple and sustainable strategy to construct a nanoreactor by connecting micelles with Pd NPs. The strategy enables us to employ a pH-induced morphological transition of sugar-based surfactant aggregates, such as worm-like, spherical, and tubular micelles, to investigate the solubilization of organic substrates. Pd NPs are mainly synthesized by the reduction of phenylboronic acid, further stabilized by the sugar-based surfactant micelles. A kinetic model is established, and the apparent activation energy of this reaction in aqueous micellar solutions is determined to be 46.7 kJ/mol. Notably, the recycled aqueous reaction mixture containing the micelles and Pd NPs can be reused.

TXPhos: a highly stable and efficient ligand designed for ppm level Pd-catalyzed Suzuki–Miyaura coupling in water

TXPhos, a highly stable and efficient ligand designed for ppm level Pd catalyzed Suzuki–Miyaura coupling reactions under micellar conditions with a TOF up to 40 000 s−1.

Minimizing base stoichiometry in Pd(0)/g-C3N4O catalyzed Suzuki–Miyaura cross-coupling reaction

A Pd nanoparticle supporting graphitic carbon nitride oxide (g-C3N4O) sheet is developed as an efficient heterogeneous catalyst for Suzuki–Miyaura cross-coupling reaction requiring just under a substoichiometric amount of exogenous base.

Induction heating enables efficient heterogeneous catalytic reactions over superparamagnetic nanocatalysts

Most catalytic processes are achieved by heating the whole reaction systems including the entire reactor, substrate and solvent, which leads to energy loss and obvious heat transfer limits. In this study, induction heating was employed to boost the catalytic Suzuki-Miyaura cross-coupling reactions by using conductive superparamagnetic microspheres with loaded Pd nanoparticles as heterogeneous catalysts. It was found that, at the same apparent reaction temperatures, the reactions by adopting the induction heating all exhibit better catalytic performance with higher conversion and yield, as compared to the reactions using conventional joule heating. The improvement is mainly attributed to the localized heating effect endowed by high efficiency of the heat transfer from the heat source to catalytic sites, which dissipates the electromagnetic energy through Néel relaxation mechanism. Moreover, it has be found that the reactions have been largely accelerated, resulting in much shorter reaction time required to approach a given value of reactant conversion. These results indicate that the unique heating method based on the superparamagnetic nanomaterials as both the inductive component and catalyst support holds a promising application for fast and efficient heterogeneous catalytic process, and exhibits potential for improving energy transfer efficiency and reducing the side reactions attributed to the uneven temperature profile.

A Novel Utilization of Water Extract of Suaeda Salsa in the Pd/C Catalyzed Suzuki-Miyaura Coupling Reaction.

Using biomass-derived solvents in various organic reactions is challenging for the fine chemicals industry. We herein report a Pd/C catalyzed Suzuki–Miyaura reaction in water extract of suaeda salsa (WES) without using external phosphine ligand, base, and organic solvent. The cross-coupling reactions were carried out in a basic WES medium with a broad substrate scope and wide functional group tolerance. Furthermore, the high purity of solid biaryl products can be obtained by column chromatography or filtration.

Noble‐metal free Suzuki–Miyaura reaction catalyzed by magnetically recyclable MOF composites

An effective metal–organic frameworks composite, Cu‐BTC@Fe3O4, was applied to catalyze Suzuki–Miyaura reaction under mild conditions and could achieve a good yield up to 98%. This magnetic noble‐metal free catalyst was proved excellent reusability for at least four cycles without loss of catalytic activity and crystallinity. X‐ray photoelectron spectroscopy confirmed that the binding energy of Fe‐2p shifted to a negative value by 0.3 eV in Cu‐BTC@Fe3O4 after catalysis; in the meantime, the binding energy of Cu‐2p shifted to a positive value by 0.1 eV. A possible bimetallic catalytic mechanism involved in this coupling reaction was proposed. In addition, the heterogeneous and recyclable properties of the catalyst were shown by hot filtration experiments, and the catalyst can be easily separated from reaction system in the presence of magnetic field.

Palladium-NHC (NHC = N-heterocyclic Carbene)-Catalyzed Suzuki–Miyaura Cross-Coupling of Alkyl Amides

Palladium-NHC (NHC = N-heterocyclic Carbene)-Catalyzed Suzuki–Miyaura Cross-Coupling of Alkyl Amides

Asymmetric Catalytic Assembly of Triple‐Columned and Multilayered Chiral Folding Polymers Showing Aggregation‐Induced Emission (AIE)

Unprecedented chiral multilayer folding 3D polymers have been assembled and regulated by uniform and differentiated aromatic chromophore units between naphthyl piers. Screening catalysts, catalytic systems and monomers were proven to be crucial for asymmetric catalytic Suzuki-Miyaura polycouplings for this assembly. X-ray crystallography of the corresponding dimers and trimers revealed the absolute configuration and the intermolecular packing pattern. Up to 61 960 Mw /41 900 Mn and m/z 4317 for polymers and oligomers, as confirmed by gel permeation chromatography (GPC) and MALDI-TOF MS, indicated that these frameworks were composed of multiple stacked layers. The resulting multiple π-assemblies exhibited remarkable optical properties in aggregated states (photoluminescence in solids and aggregation-induced emission in solutions), as well as reversible redox properties in electrochemical performance.

Pd–Ni bimetallic catalyst supported on dendrimer-functionalized magnetic graphene oxide for efficient catalytic Suzuki-Miyaura coupling reaction

A novel type of dendritic structure was grown on the magnetic graphene oxide nanocomposite surface through thiol-ene click reaction. The resulting nanocomposite was utilized as a support for immobilizing Pd–Ni bimetallic nanoparticles, which were employed in catalytic Suzuki-Miyaura coupling reaction. Transmission electron microscopy and X-ray diffraction analyses confirmed the small size and high dispersity of Pd–Ni nanoparticles. The catalyst efficiently promoted the Suzuki-Miyaura reaction of various aryl bromides and chlorides with arylboronic acids, with excellent yields under mild conditions. The combination of Pd and Ni nanoparticles together with dendritic structure of the catalyst ultimately resulted in the excellent catalytic activity. Not only the existence of dendrimer with high cavities provided the fast adsorption of reactants, but also the synergistic effect between two metals greatly increased the catalytic activity. More importantly, the introduction of Ni significantly increased the catalyst cost-effective. By magnetic separation of the catalyst, it could be retrieved for five times with no remarkable change of activity.

Synthesis of Functionalized Thiophene Based Pyrazole Amides via Various Catalytic Approaches: Structural Features through Computational Applications and Nonlinear Optical Properties.

In the present study, pyrazole-thiophene-based amide derivatives were synthesized by different methodologies. Here, 5-Bromothiophene carboxylic acid (2) was reacted with substituted, unsubstituted, and protected pyrazole to synthesize the amide. It was observed that unsubstituted amide (5-bromo-N-(5-methyl-1H-pyrazol-3-yl)thiophene-2-carboxamide (7) was obtained at a good yield of about 68 percent. The unsubstituted amide (7) was arylated through Pd (0)-catalyzed Suzuki–Miyaura cross-coupling, in the presence of tripotassium phosphate (K3PO4) as a base, and with 1,4-dioxane as a solvent. Moderate to good yields (66–81%) of newly synthesized derivatives were obtained. The geometry of the synthesized compounds (9a–9h) and other physical properties, like non-linear optical (NLO) properties, nuclear magnetic resonance (NMR), and other chemical reactivity descriptors, including the chemical hardness, electronic chemical potential, ionization potential, electron affinity, and electrophilicity index have also been calculated for the synthesized compounds. In this study, DFT calculations have been used to investigate the electronic structure of the synthesized compounds and to compute their NMR data. It was also observed that the computed NMR data manifested significant agreement with the experimental NMR results. Furthermore, compound (9f) exhibits a better non-linear optical response compared to all other compounds in the series. Based on frontier molecular orbital (FMO) analysis and the reactivity descriptors, compounds (9c) and (9h) were predicted to be the most chemically reactive, while (9d) was estimated to be the most stable among the examined series of compounds.

A highly crosslinked, mesoporous poly(ionic liquid) containing salen–Pd for efficient, eco-friendly Suzuki–Miyaura coupling reactions

Mesoporous poly(ionic liquid) obtained by hyper-crosslinking of a salen-containing poly(ionic liquid) can efficiently catalyze Suzuki–Miyaura coupling reactions with excellent recyclability under an air atmosphere in 50% aqueous ethanol.

Bimetallic Pd–Ag nanoclusters decorated micro-cellulose bio-template towards efficient catalytic Suzuki–Miyaura coupling reaction of nitrogen-rich heterocycles

Cellulose-fiber extracted from biomass waste by a simple method is used as a template for bimetallic Pd-Ag nanoclusters that exhibited photocatalytic proficiency in Suzuki-Miyaura cross-coupling of nitrogen heterocycles at room-temperature.