Suzuki Coupling Research Articles

Eco-Friendly Cellulose-Supported Nickel Complex as an Efficient and Recyclable Heterogeneous Catalyst for Suzuki Cross-Coupling Reaction.

In this work, we applied commercially available 2-pyridinecarboxylic acid to modify cellulose by simple manipulations, and then anchored low-toxicity metal nickel onto the modified cellulose to prepare the heterogeneous catalyst (CL-AcPy-Ni). The obtained catalyst was characterized by FT-IR, TG-DSC, BET, XRD, SEM-EDS, ICP-OES, XPS, and GPC. The catalytic performance of CL-AcPy-Ni in the Suzuki cross-coupling reaction was investigated using 4-methyl iodobenzene and phenylboronic acid as the model substrates reacting in THF under 120 °C for 24 h. The catalytic ability of CL-AcPy-Ni for various halobenzenes and phenylboronic acid derivatives was also further investigated under optimal conditions and demonstrated good catalytic activity, and a series of diaryls were successfully synthesized. Finally, this green nickel-based catalyst could be reused for five successive cycles by simple centrifugation.

Boosting Suzuki coupling reaction by multiscale porous Pd/carbon nanofibers photothermal catalyst

Carbon-based photothermal catalysts represent a novel, energy-saving, and eco-friendly paradigm in catalysis. In this work, multiscale porous Pd/carbon nanofibers catalyst (Pd/MPCF) was synthesized by electrospinning, CO2 thermal activating and atomic layer deposition (ALD) method. The multiscale pores of MPCF enable uniform Pd deposition on the carbon support, which showed better catalytic performance in Suzuki coupling reaction than commercial Pd/C catalyst through harnessing solar heat, resulting in a zero fossil energy consumption reaction process.

Aqueous extract of CAP-ash: A greener benchmark for Suzuki-Miyaura coupling reaction in palladium catalyzed ligand-free condition

Synthesis, molecular, spectroscopic properties, and electronic structure calculations of biphenyls derivatives have been achieved using a highly efficient catalytic amount of Pd(OAc)2 in aqueous extract of custard apple peels (CAP)-ash (AECAP) a green, highly cost-effective, operationally convenient and environmentally benign media at ambient temperature. The analytical reports showed the presence of metal oxides which are probably extracted in water produces corresponding hydroxides, which provide alkaline media in water which shows dual performance (solvent and base) for said cross-coupling transformation. The catalytic system is generated in situ based on aqueous extract and Pd(OAc)2 which requires no external base and ligand. Moreover, the study also offers insights into the frontier molecular orbitals (FMO), electronegativity, chemical potential, global electrophilicity index, ionization potential, electron affinity, chemical hardness, and softness properties of the synthesized biphenyl derivatives for understanding their stability, active sites, and biological activity using density functional theory (DFT) at the B3LYP/6–311G(d,p) level/basis.

Towards Nickel-NHC Fluoro Complexes-Synthesis of Imidazolium Fluorides and Their Reactions with Nickelocene.

While hundreds of complexes of the general formula [Ni(η5-C5H5)(NHC)(X)] exist (NHC = a N-heterocyclic carbene, X = Cl, Br, I), none is yet known with X = F. We attempted to prepare such a species by reacting nickelocene with imidazolium fluorides. Three imidazolium fluorides (ImH)+ F- [Im = (N,N'-bis-(R)-imidazolium: 1a, IMe, R = Me; 1b, IMes, R = 2,4,6-trimethylphenyl; 1c, IPr, R = 2,6-diisopropylphenyl)] were prepared and characterized by spectroscopic methods. In addition, the salts 1b [(IMesH)+ F-] and 1c [(IPrH)+ F-] were subjected single-crystal X-ray diffraction experiments. The reactions of these imidazolium fluorides with nickelocene did not lead to [Ni(η5-C5H5)(NHC)(F)] species. Instead, the reaction of 1a [(IMeH)+ F-] and 1b [(IMesH)+ F-] with nickelocene led to the salt 2 [Ni(η5-C5H5)(IMe)2]+ F- and to the square planar complex 3atrans-[NiF2(IMes)2] respectively. Both complexes were characterized spectroscopically and by single crystal X-ray diffraction. All four X-ray diffraction studies reveal hydrogen bonding and hydrogen interactions with the F atom or anion, and in some cases with solvent molecules of crystallization, and these phenomena are all discussed. Complex 2, in particular, exhibited a wide range of interesting H-bonded interactions in the solid state. Complexes 2 and 3a were tested as catalysts for Suzuki-Miyaura coupling but were not promising: complex 2 was inactive, and while 3a did indeed catalyze the reaction, it gave widely diverging results owing to its instability in solution.

In Situ generated PdNPs immobilized on polystyrene supported DABCO Dicationic ionic liquid: An efficient and reusable catalyst for Suzuki and Heck coupling reactions

A catalyst named PdNPs-DDIL@PS has been synthesized by immobilizing PdNPs on a DABCO Dicationic Ionic Liquid (DDIL) supported on Merrifield Resin (PS). The PdNPs (∼4.16 nm size) generated in situ were fully characterized using different techniques such as SEM, TEM, TGA-DTA, and XPS. It has been found that the catalyst is highly active in the Suzuki coupling reaction of various aryl bromides and aryl boronic acids in 70 % aqueous ethanol at room temperature. The catalyst produced the desired Suzuki coupling products in good to excellent yields. Additionally, the protocol was extended for the Heck coupling reactions in DMF at 80 °C with good to excellent yields. The catalyst attained a good turnover number (TON) of 160.00–189.92 and a turnover frequency (TOF) of 8.493–18.992 min−1 for the Suzuki and TON of 173.33–189.77 and TOF of 3.952–6.325 min−1 for the Heck coupling reactions. The catalyst displayed at least four times recyclability for the Suzuki coupling without a substantial decrease in product yields. Additionally, it boosts impressive environmentally-friendly credentials in Suzuki coupling reactions.

Facile Synthesis of N-(4-Bromo-3-methylphenyl)pyrazine-2-carboxamide Derivatives, Their Antibacterial Activities against Clinically Isolated XDR S. Typhi, Alkaline Phosphatase Inhibitor Activities, and Docking Studies.

The emergence of extensively drug-resistant Salmonella Typhi (XDR-S. Typhi) poses a grave public health threat due to its resistance to fluoroquinolones and third-generation cephalosporins. This resistance significantly complicates treatment options, underscoring the urgent need for new therapeutic strategies. In this study, we synthesized pyrazine carboxamides (3, 5a-5d) in good yields through the Suzuki reaction. Afterward, we evaluate their antibacterial activities against XDR-S. Typhi via the agar well diffusion method; 5d has the strongest antibacterial activity with MIC 6.25 (mg/mL). Moreover, in vitro Alkaline Phosphatase inhibitor activity was also determined; 5d is the most potent compound, with an IC50 of 1.469 ± 0.02 µM. Further, in silico studies were performed to find the type of interactions between synthesized compounds and target proteins.

Synthesis of new binary trimethoxyphenylfuran pyrimidinones as proficient and sustainable corrosion inhibitors for carbon steel in acidic medium: experimental, surface morphology analysis, and theoretical studies

In this study, synthesis and assessment of the corrosion inhibition of four new binary heterocyclic pyrimidinones on CS in 1.0 M hydrochloric acid solutions at various temperatures (30–50 °C) were investigated. The synthesized molecules were designed and synthesized through Suzuki coupling reaction, the products were identified as 5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1221), 2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1222), 1,3-diethyl-2-thioxo-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)dihydropyrimidine-4,6(1H,5H)-dione (HM-1223) and 1,3-dimethyl-5-((5-(3,4,5-trimethoxyphenyl)furan-2-yl)methylene)pyrimidine-2,4,6(1H,3H,5H)-trione (HM-1224). The experiments include weight loss measurements (WL), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). From the measurements, it can be shown that the inhibition efficiency (η) of these organic derivatives increases with increasing the doses of inhibitors. The highest η recorded from EIS technique were 89.3%, 90.0%, 92.9% and 89.7% at a concentration of 11 × 10−6 M and 298 K for HM-1221, HM-1222, HM-1223, and HM-1224, respectively. The adsorption of the considered derivatives fit to the Langmuir adsorption isotherm. Since the ΔGoads values were found to be between − 20.1 and − 26.1 kJ mol−1, the analyzed isotherm plots demonstrated that the adsorption process for these derivatives on CS surface is a mixed-type inhibitors. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), atomic force microscope (AFM) and Fourier- transform infrared spectroscopy (FTIR) were utilized to study the surface morphology, whereby, quantum chemical analysis can support the mechanism of inhibition. DFT data and experimental findings were found in consistent agreement.Graphical

Enantioselective Synthesis of P-Chiral Phosphine Oxides Bearing an All-Carbon Quaternary Stereogenic Center via Palladium-Catalyzed Domino Heck–Suzuki Reaction

Enantioselective Synthesis of <i>P</i>-Chiral Phosphine Oxides Bearing an All-Carbon Quaternary Stereogenic Center via Palladium-Catalyzed Domino Heck–Suzuki Reaction

Yellow-transmissive blue electrochromic polymers based on triphenylamine and ProDOT derivatives

Electrochromic polymer with yellow hue is few relative to those with other two primary colors due to its optical absorption at short wavelength of ≈ 450 nm. Triphenylamine (TPA) and its derivatives (TPAs) as chromogenic groups are frequently used to construct neutral yellow electrochromic polymers, however, those polymers based on TPAs usually exhibit low transmittance at oxidation state due to the residual absorption at short wavelength. Here, three neutral yellow electrochromic polymers (PBBE-1, PBBE-2 and PBBE-3) with different content ratios of ProDOT-10, TPA-4 and benzene were synthesized by Suzuki coupling reaction. With ProDOT-10 content in polymeric chain increasing, the oxidation potentials of polymers decrease gradually. Due to the twisted molecular structure, the absorption peaks of polymers almost remain unchanged when ProDOT-10 content in polymer reaches critical value, which provide an effective method for preparing neutral yellow electrochromic polymers. During oxidation process, PBBE-1 turns to black; PBBE-2 turns to dark blue; PBBE-3 turns to light grey, further to light blue. Through optimizing TBA-4/ProDOT-10 ratio, the electrochromic properties of polymers have been improved, such as optical contrast, response time and coloration efficiency. Especially, PBBE-3 possesses 40 % optical contrast at 435 nm, which is higher than reported TPAs based polymers at short wavelengths.

Novel quinoline-4-carboxamide derivatives potentiates apoptosis by targeting PDK1 to overcome chemo-resistance in colorectal cancer: Theoretical and experimental results

A series of novel N,2-diphenyl-6-(aryl/heteroaryl)quinoline-4-carboxamide derivatives were designed and synthesized using the Suzuki coupling reaction and evaluated them for their anticancer activity. These compounds were screened for anti-colon cancer activity through in-silico studies by molecular docking and molecular dynamics studies. Furthermore, the density functional theory was used to determine the molecule's electrical properties. The molecular electrostatic potential map is used to evaluate the charge distribution on the molecule surface. Unveiling that the compound 7a (binding energy of −10.2 kcal/mol) has good inhibition activity compared to other synthesized compounds (7b-7j) as well as the standard drug Gefitinib. The stability of the compound 7a with the 1OKY protein was confirmed through molecular dynamics simulation studies, indicating potential anti-colon cancer activity against phosphoinositide dependent protein kinase-1 (PDK1). The in-silico ADMET pharmacokinetic properties indicate adherence to Lipinski's rule of five for favorable safety profiles and the compound falls within the optimal range for physicochemical and pharmacokinetic properties, which is comparable to that of the standard medication drug Gefitinib. The synthesized library of compounds was further evaluated for their in-vitro anticancer potency against colon, pancreatic and breast cancer cells. The results demonstrated that the compounds effectively suppressed the proliferative potential of the screened cells in a concentration-dependent manner, as revealed by MTT assay. The anticancer potential of these molecules was further evaluated by acridine orange/PI, and Hoechst/PI which demonstrates the potential of molecules to induce apoptosis in cancer cells. Further investigations and optimization of these derivatives could lead to the development of effective anticancer strategies.

Efficient and Direct Route to 5-Iodo-4H-Quinoxalines via Copper-Catalyzed Double C-N Arylations of 1,2,3-Triiodoarenes: Potential Application towards 5-Substituted 4H-Quinoxalines

A simple, direct and regioselective protocol to substituted 5-iodo-4H-quinoxalines through domino double C-N arylations of 1,2,3-triiodobenzene and 1,2-diamines is reported. Remarkably, the N-arylation couplings proceeded unimolecularly at the vicinal positions, the most active and less hindered positions. This domino process tolerated a wide range of aromatic substrates. The reaction of electron-deficient 1,2,3-triiodoarene systems and DMEDA under the optimized conditions provided the highest isolated yields. The chemical transformation of the target compound, which serves as a valuable precursor in synthesis, was successfully demonstrated in the Suzuki-Miyaura reaction, giving the desired coupling derivatives with excellent isolated yields. This article describes a method for the first and unprecedented synthesis of 5-iodo-4H-quinoxalines that is regioselective, scalable, and provides useful derivatives for other chemical reactions.

Stereoselective Approach to the Core Structure of (+)-Phainanoid A via Strategically Engineered Cascade Polyene Cyclization.

Stereoselective synthesis of 3b and its cascade polyene cyclization to 18b have been described. Acyclic polyene 3b was prepared from allyl bromide 4 and 1,3-dithiane 5, and intermediates 4 and 5 were synthesized from the commercially available geraniol (6) and cyclopenten-2-one (8), respectively, using enantioselective reduction of ketone, Johnson-Claisen rearrangement, and the Suzuki reaction as key steps. Au(I)-mediated diastereoselective polyene cyclization of 3b efficiently afforded tetracyclic compound 18b.

Synthesis, Characterization, and Catalysis of Planar Chiral Ferrocene‐based N‐Heterocyclic Carbene Ligands and Its Metal Complexes

This study presents the development of a novel planar chiral ferrocene‐based NHC ligand and its corresponding metal complexes. The key unit of the imidazolium backbone, planar chiral ortho‐isopropyl ferrocenyl amine, was synthesized starting from (R)‐Ugi's amine. Imidazolium was obtained through the sequential condensation of glyoxal with ferrocenyl amine, followed by the ring‐closure of 1,3‐diferrocenyldiimine with chloromethylethyl ether. Chiral imidazolylidene NHC (IFcPr) metal complexes were prepared by treating imidazolium with silver oxide or base followed by transmetalation with appropriate metal salts. The steric and electronic properties of the IFcPr ligand were assessed using %Vbur and TEP, respectively. These assessments indicated that the ligand was as bulky as the adamantyl NHC ligand and exhibited strong donor ability similar to that of a triazolylidene NHC ligand. The catalytic performance of the copper and palladium complexes was evaluated in the asymmetric borylation of ethyl cinnamate and Suzuki–Miyaura coupling reactions, respectively. The IFcPr‐Cu complex catalyzed the borylation of ethyl cinnamate with bis(pinacolato) diboron, followed by oxidation to yield the hydroxy ester with 58% yield and 30% ee. In contrast, the IFcPr‐Pd‐PEPPSI complex provided the axial chiral binaphthyl compound with 59% yield and 51% ee at a low catalyst loading (0.1 mol%, TON = 590).

Enhancing photocatalytic hydrogen evolution performance for D-π-A conjugated polymers based on the perylene diimide

Efficient photocatalysts rely on constructing heterostructure with reasonable configuration. In this study, a novel conjugated polymer with a D-π-A structure was fabricated from polycondensation of perylene diimide and dibenzothiophene sulfone through the suzuki coupling reaction, during which the biphenyl was incorporated as a π-bridge. The photocatalytic hydrogen evolution performance of these copolymers were optimized by introducing different mass fractions of π-bridges via adjusting the additions of biphenyls The optimized PyBpDBSO-5 copolymer, with 17 wt.% perylene diimide and 5 wt% biphenyl, obtained photocatalytic hydrogen productivity of 48.54mmol/h g−1 under visible light without adding Pt as cocatalyst, which is 146.1 % improvement compared to the poly(dibenzothiophene-S,S-dioxide) (PDBTSO, 19.72mmol/h g−1). Based on the analysis of physical and chemical properties, electrochemical testing, the significant advantages of D-π-A configuration in promoting light absorption, photogenerated carriers transfer and separation was confirmed, which was further rationalized by the larger co-planarity of the polymer based on DFT calculations. This study provides inspiration about construction of conjugated organic polymer catalyst towards efficient photocatalysts.

Synthesis and band gap determination for 4-phenyl-7-(5-(thiazol-2-yl) thien-2-yl)benzo[c][1,2,5]thiadiazole, a new polyheterocyclic molecule with potential applications as a semiconductor in organic photovoltaic solar cells

Organic photovoltaic (OPV) solar cells are a promising emerging technology for sustainable energy generation. In these cells, the absorbing layer consists of a repeated series of aromatic organic rings with a system of π delocalized electrons, a feature that allows these materials to absorb sunlight and facilitate electron transfer. In the present work, a new tetrameric molecule with high structural complexity, 4-phenyl-7-(5-(thiazol-2-yl) thien-2-yl)benzo[c][1,2,5]thiadiazole, was synthesized by a convergent pathway. The final step of the synthetic route was the Suzuki coupling of two new dimeric molecules, obtained from commercially available raw materials such as thiophene and o-phenylenediamine. The band gap of the final compound was found to be 2.5 eV using an optical methodology and 2.38 eV using an electrochemical methodology. The results suggest that this tetrameric molecule has potential for application in OPV cells.

Size‐Dependent Catalytic Activity Over MOF‐Derived Cobalt Oxide Supported PdO Nanoparticles in Suzuki Reaction

ABSTRACTPalladium nanoparticles immobilized on ZIF 67‐derived porous CoOx were prepared by wet‐impregnation method, followed by calcination at different temperatures. The calcination temperature has been employed to effectively manipulate the size of metal nanoparticles, where higher calcination temperatures resulted in larger sizes. The experimental results revealed that by manipulating the calcination temperature, the synthesis of palladium nanoparticles with varying sizes could be effectively controlled. Increasing the calcination temperature resulted in larger particle sizes. At a calcination temperature of 350°C, the synthesis process produced the smallest palladium nanoparticles, averaging 1.35 nm in size, facilitating the reaction between aryl halides and arylboronic acids with yields ranging from 83% to 99%. Furthermore, these nanoparticles demonstrated superior catalytic activity and recyclability.

Regioselective Synthesis of α-Vinyl Boronates via a Pd-Catalyzed Mizoroki-Heck Reaction.

We report a palladium-catalyzed synthesis of α-vinyl boronates via a regioselective Mizoroki-Heck reaction between aryl triflates and vinyl boronates. This selectivity is achieved by the use of a 1,5-diaza-3,7-diphosphacyclooctane (P2N2) ligand, which results in minimal formation of the more commonly observed (linear) β-product. The choice of base, solvent, and presence of water are shown to be critical for controlling this outcome, with organic bases, nonpolar solvents, and anhydrous conditions favoring the Heck product and suppressing the competitive Suzuki-Miyaura coupling product.

Total Synthesis of the Phenylnaphthacenoid Type II Polyketide Antibiotic Formicamycin H via Regioselective Ruthenium-Catalyzed Hydrogen Auto-Transfer [4 + 2] Cycloaddition.

The first total synthesis of the pentacyclic phenylnaphthacenoid type II polyketide antibiotic formicamycin H is described. A key feature of the synthesis involves the convergent, regioselective assembly of the tetracyclic core via ruthenium-catalyzed α-ketol-benzocyclobutenone [4 + 2] cycloaddition. Double dehydration of the diol-containing cycloadduct provides an achiral enone, which upon asymmetric nucleophilic epoxidation and further manipulations delivers the penultimate tetracyclic trichloride in enantiomerically enriched form. Subsequent chemo- and atroposelective Suzuki cross-coupling of the tetracyclic trichloride introduces the E-ring to complete the total synthesis. Single-crystal X-ray diffraction analyses of two model compounds suggest that the initially assigned stereochemistry of the axially chiral C6-C7 linkage may require revision.

An Acid-Responsive Fluorescent Molecule for Erasable Anti-Counterfeiting.

A tetraphenylethylene (TPE) derivative, TPEPhDAT, modified by diaminotriazine (DAT), was prepared by successive Suzuki-Miyaura coupling and ring-closing reactions. This compound exhibits aggregation-induced emission enhancement (AIEE) properties in the DMSO/MeOH system, with a fluorescence emission intensity in the aggregated state that is 5-fold higher than that of its counterpart in a dilute solution. Moreover, the DAT structure of the molecule is a good acceptor of protons; thus, the TPEPhDAT molecule exhibits acid-responsive fluorescence. TPEPhDAT was protonated by trifluoroacetic acid (TFA), leading to fluorescence quenching, which was reversibly restored by treatment with ammonia (on-off switch). Time-dependent density functional theory (TDDFT) computational studies have shown that protonation enhances the electron-withdrawing capacity of the triazine nucleus and reduces the bandgap. The protonated TPEPhDAT conformation became more distorted, and the fluorescence lifetime was attenuated, which may have produced a twisted intramolecular charge transfer (TICT) effect, leading to fluorescence redshift and quenching. MeOH can easily remove the protonated TPEPhDAT, and this acid-induced discoloration and erasable property can be applied in anti-counterfeiting.

Design and synthesis of N-formyl/carbothioamide based pyrazoline analogs using Pd(PPh3)4 catalyst: Cytotoxicity, apoptosis, and molecular docking studies

To expand the scope of our research and find anticancer drugs with novel structures, heterocyclic derivatives (3a-3n) were designed and synthesized via Suzuki coupling reaction in the presence of Pd(PPh3)4 [Tetrakis(triphenylphosphine)-palladium(0)] catalyst with good yields. The synthesized heterocyclic analogs were characterized using various spectroscopic techniques like 1H, 13C NMR, and FT-IR spectroscopy. The cytotoxicity of heterocyclic analogs (3a-3n) was carried out by MTT assay towards breast cancer cell (MCF-7), and human normal cells (HepG2), analog 3j exhibited excellent activity against an MCF-7 (IC50 = 5±1.58µM) and low toxicity against the HepG2 (IC50 = >80µM). Furthermore, the anticancer activity of lead analog against the MCF-7 cancer cell line was confirmed using flow cytometry. Molecular docking study revealed that the derivative fits well at the active site of the target protein epidermal growth factor receptor tyrosine kinase.