Suzuki-Miyaura Coupling Reaction Research Articles

Biosynthesis Parameters Control the Physicochemical and Catalytic Properties of Microbially Supported Pd Nanoparticles.

The biosynthesis of Pd nanoparticles supported on microorganisms (bio-Pd) is achieved via the enzymatic reduction of Pd(II) to Pd(0) under ambient conditions using inexpensive buffers and electron donors, like organic acids or hydrogen. Sustainable bio-Pd catalysts are effective for C-C coupling and hydrogenation reactions, but their industrial application is limited by challenges in controlling nanoparticle properties. Here, using the metal-reducing bacterium Geobacter sulfurreducens, it is demonstrated that synthesizing bio-Pd under different Pd loadings and utilizing different electron donors (acetate, formate, hydrogen, no e- donor) influences key properties such as nanoparticle size, Pd(II):Pd(0) ratio, and cellular location. Controlling nanoparticle size and location controls the activity of bio-Pd for the reduction of 4-nitrophenol, whereas high Pd loading on cells synthesizes bio-Pd with high activity, comparable to commercial Pd/C, for Suzuki-Miyaura coupling reactions. Additionally, the study demonstrates the novel synthesis of microbially-supported ≈2nm PdO nanoparticles due to the hydrolysis of biosorbed Pd(II) in bicarbonate buffer. Bio-PdO nanoparticles show superior activity in 4-nitrophenol reduction compared to commercial Pd/C catalysts. Overall, controlling biosynthesis parameters, such as electron donor, metal loading, and solution chemistry, enables tailoring of bio-Pd physicochemical and catalytic properties.

Boosted electrostatic interaction by surface sulfonation over Calixarene-TPE copolymer for prompt adsorption of cationic contaminates

Removal of cationic pollutants, including dyes, herbicides, and antibiotics from water is significant owing to their persistence, bioaccumulation, carcinogenicity, mutagenicity, and reproductive risks. In this paper, a calixarene-tetraphenyl ethylene containing copolymer adsorbent, named CP-TPE, was synthesized using the Suzuki-Miyaura coupling reaction between the resorcinol calixarene and tetraphenyl ethylene boric acid esters. Subsequently, the phenolic groups on the CP-TPE were further reacted with chlorosulfonic acid, resulting in a sulfonated product named CP-TPE-SO3H. The introduction of the sulfonate groups not only significantly improved the hydrophilicity of CP-TPE-SO3H but also enhanced the electrostatic interaction between CP-TPE-SO3H and cationic molecules, achieving an outstanding maximum adsorption capacity for paraquat (representative herbicide, 300.06 mg g−1) and tetracycline hydrochloride (representative antibiotic, 888.74 mg g−1), which surpassed the majority of reported polymeric adsorbents. Moreover, the k2 of CP-TPE-SO3H on TC (0.0407 g mg−1 min−1) reached the maximum value reported so far. This study demonstrated the significance and superiority of sulfonation modification in synthesizing POPs-based adsorbents, which can be potentially employed in real wastewater treatment.

Aminative Suzuki-Miyaura coupling.

The Suzuki-Miyaura and Buchwald-Hartwig coupling reactions are widely used to form carbon-carbon (C-C) and carbon-nitrogen (C-N) bonds, respectively. We report the incorporation of a formal nitrene insertion process into the Suzuki-Miyaura reaction, altering the products from C-C-linked biaryls to C-N-C-linked diaryl amines and thereby joining the Suzuki-Miyaura and Buchwald-Hartwig coupling pathways to the same starting-material classes. A combination of a bulky ancillary phosphine ligand on palladium and a commercially available amination reagent enables efficient reactivity across aryl halides and pseudohalides, boronic acids and esters, and many functional groups and heterocycles. Mechanistic insights reveal flexibility on the order of bond-forming events, suggesting potential for expansion of the aminative cross-coupling concept to encompass diverse nucleophiles and electrophiles as well as four-component variants.

Difluoro Dipyridomethene Boron Complexes: Synthesis, Characterization, and Ab Initio Calculations.

Molecular engineering studies on the meso-cyano difluoro dipyridomethene boron complexes are presented and two series (a and b) of novel fluorophores are extensively studied. Halogenated derivatives were reacted under Suzuki-Miyaura or Sonogashira cross coupling reactions to introduce electron-donating or electron-withdrawing functional groups on positions 1 and 2 of the aromatic ligand. All derivatives were obtained in 14-90% yields and studied in detail by structural, photophysical, and computational analyses. Both series display excellent emissive properties in solution with blue to orange fluorescence emission upon blue light absorption and promising features as solid emitters. All the spectroscopic measurements are supported and confirmed by first-principles theoretical calculations combining TD-DFT and CC2. Series b, featuring an aryl substituent onto position 1 of the aromatic core, showed significantly large Stokes shifts values.

BIII-Subporphyrins Bearing Distorted Metal-Coordinating Straps: CuII-Assisted meso-Fabrications.

BIII-subporphyrins 4, 5, and 6 possessing metal-coordinating carbaporphyrin-like pockets were synthesized by Suzuki-Miyaura coupling reactions. Compounds 4 and 5 gave PdII complexes 4-Pd and 5-Pd upon metalation with Pd(OAc)2 but did not give either their NiII or CuII complexes. Conversely, 6 was expected to induce distorted square planar coordination because of its 2,5-di(pyrid-2-yl)pyrrole strap. Indeed reaction of 6 with Cu(OAc)2 did not give its CuII complex but produced meso-alkoxy and meso-phenoxy products in the presence of alcohols and phenol, possibly via CuII-mediated C-H bond functionalization, which was further extended to meso-C-C bond-forming fabrications by using organoboronic acids. These CuII-mediated C-H bond meso-fabrications are the first example for porphyrinoid substrates.

Nanocatalytic and antimicrobial potency of CQD@Pd nanoparticles: Experimental and theoretical approach

A single-pot approach has been developed for the fabrication of novel heterogeneous nanocatalyst of carbon quantum dots doped palladium (CQD@Pd-NPs) nanoparticles. Herein, Aegle marmelos fruit extract was utilized as a reducing and capping agent for the fabrication of CQD@Pd-NPs. Synthesis of metallic nanoparticles through green chemistry route is environment beneficial technology owing to its low cost and ecological compatibility. The formation of CQD-NPs and CQD@Pd-NPs was confirmed with high-end sophisticated techniques and theoretical studies. The computational analysis revealed a discernible decrease in the band gap value (Egap = ELUMO - EHOMO) from 0.08 eV to 0.03 eV upon the introduction of Pd atoms into carbon quantum dots (CQDs). Therefore, computational data also authenticates the stability of the CQD@Pd-NPs nanocatalyst which was predominantly supported by electrostatic interaction between Pd and CQDs. The developed nanocatalyst has vouched for an effective candidature in the Suzuki-Miyaura and Mizoroki-Heck coupling reactions with a superior selectivity for product formation. The excellent antibacterial properties against E. coli and S. aureus were further supported by visualizing bacterial growth, inhibition zone, FESEM results and molecular docking studies. Moreover, the nanocatalyst displayed facile separation from the reaction system and showcased efficient recyclability with minimal activity loss. This further supports an effective potential over existing commercial catalysts and holds immense future prospective in industrial applications.

Preparation of recyclable magnetic palladium nanocatalysts by dispersion strategy based on sodium alginate for reduction of p-nitrophenol and Suzuki-Miyaura coupling

Palladium (Pd) has excellent catalytic performance, its application is seriously limited by low atomic utilization and weak recovery capacity. To solve these problems, we report a universal palladium nanocatalysts preparation strategy by taking advantage of the rich chemistry of sodium alginate (SA). SA units not only self-assemble into a cross-linked porous carboxyl and hydroxyl framework but also can coat different substrates. Benefiting from the distinguished chelation of SA, metallic nanocatalysts can be achieved. As a proof-of-concept demonstration, Pd loading on nano-Fe3O4 modified with SA and investigated their catalytic capabilities. The catalyst was Fe3O4 nanoparticles encapsulated by SA film loaded with 0.4 wt% of Pd. It has a particle size around 100 nm and has good superparamagnetism with a saturation strength of 76.26 emu/g. It exhibited good catalytic activity at TOF = 660 h−1 and TOF = 4311 h−1 in typical Suzuki-Miyaura coupling reaction and the reduction of p-nitrophenol, respectively, and showed appreciable recyclability in the test of recyclability. Thus, our findings demonstrate that recyclable magnetic palladium nanocatalysts have several attractive features, such as easy preparation, outstanding catalytic activity and reusability. This work lays the foundation for the preparation of palladium nanocatalysts and the potential application of SA in the field of catalysts.

Fabrication of thiosemicarbazone-based Pd(II) complexes: structural elucidations, catalytic activity towards Suzuki-Miyaura coupling reaction and antitumor activity against TNBC cells.

Currently, there are many uses of metal complexes, especially in the fields of medicinal chemistry and catalysis. Thus, fabrication of new complexes which perform as a catalyst and chemotherapeutic drug is always a beneficial addition to the literature. Herein, we report three heterocyclic thiosemicarbazone-based Pd(II) complexes [Pd(HL1)Cl] (C1), [Pd(L2)(PPh3)] (C2) and [Pd(L3)(PPh3)]Cl (C3) having coligands Cl and PPh3. Thiosemicarbazone ligands (H2L1, H2L2 and HL3) and the complexes (C1-C3) were characterized methodically using several spectroscopic techniques. Single-crystal X-ray diffraction methods reveal that the structural environment around the metal center of C2 is square planar, while for C1 and C3 it is a slighty distorted square plane. The supramolecular network of compounds was built via hydrogen bonds, C-H⋯π and π⋯π interactions. Density functional theory (DFT) study of the structure of the complexes supports experimental findings. The application of these complexes as catalysts toward Suzuki-Miyaura coupling reactions has been examined with various aryl halides and phenyl boronic acid in PEG 400 solvent. The complexes displayed good biomolecular interactions with DNA/protein, with a binding constant value of the order of 105 M-1. C3 showed greater binding efficacy toward these biomolecules than the other complexes, which might be due to the cationic nature of C3. Furthermore, antitumor activity of the complexes was studied against the human triple-negative breast cancer (TNBC) cell line MDA-MB-231. It was found that C3 was more toxic (IC50 = 10 ± 2.90 μM) toward MDA-MB-231 cells than the other complexes. A known chemotherapeutic drug, 5-fluorouracil, was included as positive control. The programmed cell death mechanism of C3 was confirmed. Additionally, complex-induced apoptosis was confirmed and occurred via a mitochondria-dependent (intrinsic) pathway.

Electron-donating arene-substituted pentacenedione derivatives: a study of structural, electronic, and electrochemical properties.

A new series of redox-active tetraryl-substituted pentacenedione derivatives, namely Ar4-PDs, was prepared through Suzuki-Miyaura coupling reactions between a bis(dibromomethane)pentacenedione and various arene boronic acids. Single-crystal X-ray diffraction analysis and density functional theory (DFT) calculations have confirmed that these Ar4-PDs possess highly twisted conformations due to the significant steric encumbrance between the Ar substituents and the anthraquinodimethane moiety. Cyclic voltammetric analysis revealed that the nature of the Ar group critically influences the redox properties of Ar4-PDs. In the case where the Ar group is a strong electron donor, triphenylamino (TPA), the Ar4-PD derivative exhibits an amphoteric redox behavior with a narrowed electrochemical band gap (1.38 eV) and a noticeable intramolecular charge transfer (ICT) band in the visible region of the spectrum. The twisted molecular conformation is believed to facilitate through-space interactions between the donor (TPA) and acceptor (anthraquinone) groups, while protonation of this compound with a strong organic acid can further enhance the ICT effect.

Stepwise construction of a metallocatenane based on non-labile bis(terpyridine)-CdII complexes.

A series of metalloligands bearing homoleptic 2,2':6',2''-terpyridine (tpy)-CdII complexes has been successfully synthesized. The formation of ML1 was accomplished through a sequence of Suzuki-Miyaura coupling and complexation reactions, offering an alternative method to produce tpy-based metalloligands under relatively mild conditions. Moreover, the metallomacrocycle C1 and metallocatenane C2 were self-assembled from heteroleptic complexation reactions involving ML1 and suitable counterparts.

A palladium-catalyzed synthesis of cyclic alkenyl boronates from alkenyl chlorides.

A palladium-catalyzed borylation of cyclic alkenyl chlorides with B2pin2 is reported. This transformation allows for the conversion of diverse cyclic alkenyl chlorides into synthetically versatile alkenyl boronates with moderate to excellent yields. The utility of this reaction has been demonstrated with practical Suzuki-Miyaura coupling and aziridination reactions, which allow access to functionalized olefins and valuable boron-substituted aziridines.

Oxazaborolidinones: Steric Coverage Effect of Lewis Acidic Boron Center in Suzuki-Miyaura Coupling Reactions.

It was demonstrated that α-hydroxycarboxamide is an excellent boron-protecting group. The reaction between α-hydroxycarboxamide and organoboronic acids produced stable oxazaborolidinones (OxBs), in which the -hybridized boron atom was sterically protected by α-hydroxycarboxamide. The alkyl groups of the α-hydroxycarboxamide moiety can dynamically cover the p-orbital of the -hybridized boron center, creating a small space around the boron atom, allowing for smooth transmetalation by a Pd catalyst and easy deprotection by water. This protecting phenomenon is effective for readily purification, Suzuki-Miyaura coupling reactions with unstable boronic acids and iterative cross-couplings.

Synthesis of biphenyl via sustainable Suzuki-Miyaura coupling reaction using mesoporous MCF-supported tin-palladium nanoparticles

The current work presents a novel approach to synthesizing monometallic palladium (Pd) and bimetallic tin-palladium (Sn-Pd) nanoparticles anchored to mesostructured cellular foam silica (MCF). The monometallic catalyst Pd@MCF was prepared by the impregnation method, whereas the bimetallic catalyst Pd@MCF(Sn) was prepared by a green electroless reduction method. Our findings demonstrate that the bimetallic Sn-Pd nanoparticles produced through green electroless reduction exhibit no aggregation or clustering, and possess high and uniform dispersion, smaller average particle size and a narrower distribution of particle size than Pd nanoparticles obtained via impregnation. The synthesis of Pd@MCF(Sn) used tin as one of the metallic components of the catalyst and also as a reducing agent rather than conventionally used harmful reducing agents in the electroless reduction method. Remarkably, the introduction of tin into the catalyst system also displays a synergistic effect in the Suzuki-Miyaura coupling (SMC) reaction. The monometallic Pd@MCF catalyst was outperformed by the bimetallic Pd@MCF(Sn) catalyst in terms of catalytic activity for SMC reaction of phenylboronic acid with iodobenzene to produce biphenyl without using toxic reagents, organic solvents, costly phosphine ligands or protective atmospheres. This study also explored and optimized the factors controlling the reaction rate, offering insightful information to improve the production of biphenyl. The reaction follows a second-order kinetics with an apparent activation energy of 8.2 Kcal/mol by applying the Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism. Here, we present a promising strategy for formulating a highly effective and eco-friendly catalyst for sustainable production of biphenyl using Suzuki-Miyaura coupling reaction.

Decoration of MnFe2O4@cys with Pd as a highly efficient nanocatalyst in C-C coupling reaction at ambient temperature

An environmentally friendly nano-catalyst was prepared by the functionalization of MnFe2O4 with cysteine (MnFe2O4@cys) and decoration with Pd(0) (MnFe2O4@cys/Pd) and fully characterized with physicochemical techniques. As-prepared MnFe2O4@cys/Pd was applied as a catalyst in the carbon-carbon (C-C) Suzuki-Miyaura coupling reaction using various aryl halides and phenylboronic acid with electron withdrawing and electron donating groups. The MnFe2O4@cys/Pd catalyst showed high efficiency, achieving significant reaction conversions and yields even with small amounts used in mild conditions such as room temperature and green solvents. The new nanocatalyst was stable, easily isolated by an external magnet, and was used at least 5 times without any noticeable decrease in its catalytic efficiency.

Bimetallic Cu/Pd(ppm)-catalyzed Suzuki-Miyaura couplings: DFT studies on mechanism, roles of Pd(ppm) and ligands

Transition metal-catalyzed Suzuki-Miyaura coupling (SMC) reaction is an important method to constructe the C-C bond. In this work, the mechanisms of SMC between ArI and ArB(OH)2 (Ar=C6H4(OCH3)) catalyzed by single [Cu] catalyst and bimetallic [Cu]/[Pd] catalysts have been studied by DFT calculations. Comparing to the N, O-bidentate ligand, the N, P-bidentate ligand coordinated [L12-Cu] catalyst is not efficient for the above reaction, due to the high energy barrier of the C-C coupling procedure. The different coordination mode of the N, O-bidentate ligand increases the positive charge of coupling C atom, lowering the energy barrier when catalyzed by [L13-Cu]. The [Cu]/[Pd] catalyzed process involves two cycles: LCuAr is obtained from the [Cu] catalyzed cycle by the reaction between ArB(OH)2 and [L12Cu]. The [Pd] catalyzed cycle consists of four steps: L12Pd(0) insertion into C-I bond by oxidation addition, coordination transformation, transmetallation between LCuAr and ArPdI, and C-C coupling by reductive elimination. In these two cycles, the coordination transformation of the Pd is the rate-determining step. The participation of [Pd] catalyst changes the C-C coupling process from the Cu center to the Pd center, which lowers the energy barrier and makes the reaction become easier.

Decarboxylative Iodination and Suzuki-Miyaura Coupling Reactions to Access Chiral 3,3'-Diaryl-1,1'-bi-2-naphthols.

An efficient synthesis of the enantiomerically pure 3,3'-bis-arylated BINOLs is accomplished through decarboxylative iodination of the dimethyl ether derivative of BINOL-3,3'-dicarboxylic acid followed by Suzuki-Miyaura coupling using a one-pot protocol. The decarboxylative iodination is effected with the dimethyl ether derivative of BINOL-3,3'-dicarboxylic acid using iodine as a terminal oxidant and the cheaply available K3PO4 as a base under neat conditions. This protocol facilitated the introduction of the aryl group at the 3,3'-position on the binaphthyl system using aryl boronic acid through a palladium-catalyzed Suzuki-Miyaura coupling reaction.

Colloid template route for the synthesis of polyaniline-Pd nanocomposite and catalytic activity study for Suzuki-Miyaura coupling reaction in aqueous media

Colloid template route for the synthesis of polyaniline-Pd nanocomposite and catalytic activity study for Suzuki-Miyaura coupling reaction in aqueous media

An efficient and recyclable palygorskite-supported palladium catalyst for Suzuki–Miyaura coupling reactions in water at room-temperature

An efficient and recyclable palygorskite-supported palladium catalyst for Suzuki–Miyaura coupling reactions in water at room-temperature

Palladium Catalysts Supported in Microporous Phosphine Polymer Networks.

A new set of microporous organic polymers (POPs) containing diphosphine derivatives synthesized by knitting via Friedel-Crafts has been attained. These amorphous three-dimensional materials have been prepared by utilizing diphosphines, 1,3,5-triphenylbenzene, and biphenyl as nucleophile aromatic groups, dimethoxymethane as the electrophilic linker, and FeCl3 as a promoting catalyst. These polymer networks display moderate thermal stability and high microporosity, boasting BET surface areas above 760 m2/g. They are capable of coordinating with palladium acetate, using the phosphine derivative as an anchoring center, and have proven to be highly efficient catalysts in Suzuki-Miyaura coupling reactions involving bromo- and chloroarenes under environmentally friendly (using water and ethanol as solvents) and aerobic conditions. These supported catalysts have achieved excellent turnover numbers (TON) and turnover frequencies (TOF), while maintaining good recyclability without significant loss of activity or Pd leaching after five consecutive reaction cycles.

Organometallic Nickel(II) Phosphine Complexes for Suzuki-Miyaura Cross-Coupling; A Greener Alternative?

In this experiment, students perform a Grignard reaction under air-free conditions to synthesize and isolate organometallic Ni(II) phosphine complex(es) that are used as pre-catalysts for a Suzuki-Miyaura Coupling reaction in tert-amyl alcohol.