Catalyzed Suzuki Miyaura Cross-coupling Research Articles

Microwave Irradiated, Sodium Aluminate Supported and Zinc Catalyzed Suzuki-Miyaura Cross-Coupling Reaction on Fused Tricyclic Oxa-Aza-Quinolone: A Green Protocol

Alternative synthesis methods are need of the hour to provide easy protocol for synthesizing biologically active heterocyclic compounds. In this connection, this paper describes the development of a concise, convergent protocol for diversely substituted Suzuki–Miyaura cross-coupling reactions of heteroaryl bromides and boronic acids under microwave irradiation using Sodium aluminate (NaAlO2) as a solid support as well as base. According to my knowledge, this is the first report of the strategy that involves the use of zinc as a catalyst on fused tricyclic di-halo quinolones in a solvent-free condition using simple microwave irradiation. Earlier research from the same laboratory established a solid support assisted Suzuki–Miyaura cross-coupling reaction for forming C–C bonds under the influence of microwave irradiation. Therefore, sodium aluminate (NaAlO2) was attempted as a base and solid support instead of traditional mineral bases. Moreover, zinc was used as a catalyst replacing palladium. The new method is unique and effective due to its energy economy, procedural simplicity, and general applicability. Moreover, the use of Sodium aluminate (NaAlO2) is expected to extend this green-protocol and atom-friendly chemistry for the synthesis of varied heterocyclic compounds of interest.

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.

Adsorption and removal of ethidium bromide from aqueous solution using optimized biogenic catalytically active antibacterial palladium nanoparticles.

Due to being low cost and eco-friendly, biological nanomaterial synthesis and development have made broad spectral progress. This study aimed to optimize the phytomediated synthesis of catalytically active, antibacterial palladium nanoparticles (PdNPs) for adsorption-based removal of ethidium bromide (EtBr) from an aqueous solution. Optimization of synthesis demonstrated that a precursor to extract ratio of 4:1, pH 3, and incubation at 80°C for 60min were the optimum conditions that led to the synthesis of negatively charged, highly stable, polycrystalline, spherical, and monodispersed PdNPs of 5-10nm. When tested as catalysts, PdNPs successfully catalyzed Suzuki-Miyaura cross-coupling between aryl halides and arylboronic acids resulting in the synthesis of 4-acetylbiphenyl. Furthermore, the antibacterial activity test demonstrated that biogenic PdNPs were most effective and potent against Staphylococcus aureus and Proteus vulgaris followed by Escherichia coli, Bacillus subtilis, and Bacillus cereus. In addition, PdNPs were found as an excellent adsorbent for adsorption of EtBr from water as the adsorption reaction obeyed pseudo-second-order kinetics with a linear regression coefficient (R2 > 0.995). The adsorption reaction fitted well with the Freundlich and Temkin isotherm models, indicating multi-layer adsorption. Estimating thermodynamic parameters resulted in a positive value of ΔH0 and ΔG0, demonstrating adsorption was non-spontaneous and endothermic.

Orthogonal C-B Bond Transformation as an Approach for Versatile Synthesis of End-Functionalized Polymers.

Conventionally inaccessible end-functionalized vinyl polymers were synthesized via orthogonal side-chain replacement for terminal and repeating units of poly(alkenyl boronate)s. A terminal-defined polymer of isopropenyl boronic acid pinacol ester (IPBpin) was synthesized via RAFT polymerization, and subsequent cobalt (Co)-catalyzed end olefination afforded the polymer carrying the C(sp2)-B bond at the terminal and the C(sp3)-B bond in repeating units. Herein, the terminal C(sp2)-B bond was selectively transformable via palladium (Pd)-catalyzed Suzuki-Miyaura cross coupling, and subsequent transformation of the repeating C(sp3)-B unit gave the poly(α-methyl vinyl alcohol) [poly(MVA)] bearing various functional groups at the terminal. The boron-based stepwise polymer reaction thus overcame the synthetic difficulty of the end-functionalized poly(MVA), which is ascribed to the poor polymerization ability of the corresponding acetate monomer, i.e., isopropenyl acetate.

Arylation of halogenated thiophene carboxylate via Suzuki–Miyaura reaction: Anti-bacterial study against clinically isolated extensively drug resistant Escherichia coli sequence type 405 and computational investigation

In present study, Pd(0) catalysed Suzuki-Miyaura cross coupling reaction was used to synthesize 2,4-biarylphenyl-5-arylthiophene-2-carboxylate (7a–7f) and 2-aryl-4-chlorophenyl-5-arylthiophene-2-carboxylate derivatives (8a–8l) in moderate to good yields. While 2,4-dibromophenyl-5-bromothiophene-2-carboxylate (4) and 2-bromo-4-chlorophenyl-5-bromothiophene-2-carboxylate (5) were synthesized via Steglich esterification of 5-bromothiophene-2-carboxylic acid (1) with 2,4-dibromo phenol (2) and 2-bromo-4-chlorophenol (3) in the presence of N, N΄-dicyclohexylcarbodiimide (DCC) and 4-(dimethylamino)pyridine (DMAP). 1 H and 13 C NMR were used to confirm all of the compounds. To screen out the most active lead compounds, binding interactions of all synthesized compounds with MurD and MurE Escherichia coli proteins were evaluated theoretically via molecular docking studies indicating the good binding affinities. DFT calculations were performed out by using DFT-B3LYP/3-21g and structural and reactivity parameters were calculated. Compounds 5, 8b, 8e, 8h , and 8j have demonstrated potential reactivities and charge distributions that indicate their efficiency towards biological targets. These chemicals were tested in vitro for antibacterial activity against Gram-negative bacteria ( Escherichia coli ) at different concentrations based on theoretical results. The total results were quite close to the theoretical predictions and compound 8j was found to be having the greatest potential value, strongest binding affinities, and a promising antibacterial agent with MIC value of 50 mg/ml against Escherichia coli.

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

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.

DABCO-mediated decarboxylative cyclization of isatoic anhydride with aroyl/heteroaroyl/alkoylacetonitriles under microwave conditions: Strategy for the synthesis of substituted 4-quinolones

An efficient, 1,4-diazabicyclo[2.2.2]octane(DABCO)-mediated decarboxylative cyclization of isatoic anhydrides with active methylene groups namely aroyl/heteroaroyl/alkoylacetonitriles under microwave condition was developed for the synthesis of substituted 4-quinolones. This method utilizes commercially available substrates, occurs under mild conditions, short reaction time, good to excellent yields, easy scale-up, and is compatible with a wide substrate scope. 4-Quinolones (3) obtained by this DABCO-mediated approach were further explored in order to evaluate their synthetic applicability. Initially, 4-quinolone derivatives were efficiently transformed into corresponding 4-Chloro-2-phenyl-quinoline-3-carbonitriles. Further, 2,4-Diphenyl-quinoline-3-carbonitriles were prepared by palladium catalyzed Suzuki-Miyaura cross-coupling of 4-Chloro-2-phenyl-quinoline-3-carbonitrile with aryl boronic acids.

Synthesis of new functionalized triarylmethanes via Suzuki cross-coupling and Heck-type vinylation reactions

A novel class of triarylmethanes (TRAMs) containing one or two biaryl moieties was synthesized efficiently through the Pd(PPh 3 ) 4 -catalyzed Suzuki–Miyaura cross-coupling reaction of brominated TRAMs with arylboronic acid derivatives. We also demonstrate that brominated TRAMs can be efficiently functionalized via a one-pot, two-step Pd-catalyzed Heck-type process. This protocol provides convenient access to diverse vinylated TRAMs that are generally not obtained by using the common synthetic methods for TRAMs.

Synthesis, characterization and photophysical properties of π-conjugated novel phenothiazine substituted acrylonitrile D–A derivatives: Orange to red emission

• Phenothiazine substituted acrylonitrile derivatives are synthesized. • Optical band gap values range from 2.296 to 2.407 eV. • Measured experimental quantum yields ( φ) are range from 0.065 to 0.121. • The 5% weight loss temperatures of derivatives are in the range 170–250 °C. By utilizing palladium catalyzed Suzuki–Miyaura cross coupling reaction, a series of novel organic dyes containing phenothiazine were designed, synthesized (abbreviated as PTA-5(a–d)) in good yield and confirmed by spectroscopic methods. These bipolar dyes comprise of PTA moiety as the electron donor unit (D) and acrylonitrile as the electron acceptors/anchoring unit (A). By introducing substituents at C(3) and C(7) positions, Intramolecular Charge Transfer character of PTA was improved. Their photophysical/solvatochromic properties were examined with the assistance of DFT computations and the synthesized molecules exhibit red fluorescence with decent quantum yields. The computed and experimental results are found to be in accordance. Differential scanning calorimetry and thermogravimetric analysis showed the thermal stabilities of the compounds. The highest occupied molecular orbitals, lowest unoccupied molecular orbitals and energy band gap were computed with the help of frontier molecular orbitals. The outcome exhibit that the novel (D–A) chromophores could play important role in organic optoelectronics.

Engineering Electronic Structure of Single-Atom Pd Site on Ti 0.87 O 2 Nanosheet via Charge Transfer Enables C–Br Cleavage for Room-Temperature Suzuki Coupling

The palladium (Pd)-catalyzed Suzuki reaction is widely applied in the pharmaceutical industry, where constructing highly active and low-cost Pd sites are impendent. Here, we report the fabrication ...

Palladium-Catalyzed Synthesis and Anticancer Activity of Paclitaxel-Dehydroepiandrosterone Hybrids.

According to the activity–structure relationship of the C-13 side chain in paclitaxel or docetaxel, eighteen novel paclitaxel–dehydroepiandrosterone (DHEA) hybrids were designed and synthesized by Pd(II)-catalyzed Suzuki–Miyaura cross-coupling of 17-trifluoromethanesulfonic enolate-DHEA with different aryl boronic acids. The in vitro anticancer activity of the hybrids against a human liver cancer cell line (HepG-2) was evaluated by MTT assay, showing that most of these hybrids possessed moderate antiproliferative activity against the HepG-2 cancer cell line. Among these hybrids, three ones (7b, 7g, and 7i) with ortho-substituents in the phenyl group of the D-ring of DHEA analogues exhibited moderate anticancer activity. The optimal compound 7i showed superior anticancer activity against the HepG-2 cell line with an IC50 value of 26.39 μM.

Introduction of Low-Barrier High-Throughput Experimentation in the Undergraduate Laboratory: Suzuki—Miyaura Reaction

A contemporary undergraduate laboratory experiment incorporating parallel microscale experimentation was developed for the well-defined palladium catalyzed Suzuki–Miyaura cross coupling of 4-fluorophenylboronic acid with both 4-chloro- and 4-bromoanisole using 11 diverse phosphine ligands and one ligandless control. This laboratory introduces students to low-barrier high-throughput experimentation (HTE) technique that is widely utilized in both academic and industrial research settings. This experiment compliments current topics discussed in organic chemistry, inorganic chemistry, and organometallic chemistry lecture courses and serves to reinforce the students’ understanding of fundamental concepts of transition metal mediated cross-coupling reactions. Students are also exposed to common analytical tools (thin layer chromatography (TLC) and high-pressure liquid chromatography (HPLC)) used in research settings to analyze the corresponding experimental data.

Development of a Tethered Palladium–BODIPY Dual Catalyst for Enhanced Photo- and Thermally Activated Catalysis, and for Promoting Sequential Reactivity

In recent years there has been a growing interest in merging different types of catalysis to create new multistep catalytic processes. However, the majority of reported dual catalysis strategies use a mixture of individual catalysts, with limited reports of dual catalysis reactions where the different catalysts are combined in a single compound. This work reports the synthesis of a tethered palladium-BODIPY dual catalyst to enable increased synergistic interactions between the catalytic centres. Detailed analysis, including single crystal X-ray crystallography, absorption, fluorescence, and phosphorescence measurements, and kinetic analyses to determine singlet oxygen quantum yields, confirm that chemical tethering results in a significant increase in the photocatalytic potential of the palladium-BODIPY dual catalyst, relative to the parent BODIPY chromophore. Interestingly, the palladium-BODIPY complex also exhibited rare long-lived room temperature phosphorescence. Catalytic applications of the palladium-BODIPY dual catalyst indicate that chemical tethering increases the reactivity of the catalytic centres for both photocatalytic oxidation of thioanisole and palladium catalysed Suzuki–Miyaura cross coupling, highlighting that enhancements in both photo and thermally activated catalysis can be achieved on chemical tethering. In addition, the dual catalytic potential of the palladium-BODIPY catalyst was demonstrated using a representative sequential photocatalytic oxidation–cross coupling reaction.

NHC-Pd(II)-azole complexes catalyzed Suzuki–Miyaura cross-coupling of sterically hindered aryl chlorides with arylboronic acids

In order to synthesize hindered biaryls efficiently, a series of NHC-Pd(II)-azole complexes bearing sterically hindered ligands were synthesized and characterized. The steric environment effect as well as the electronic effect of the azole ligands has been assessed. All these complexes were applied in the Suzuki–Miyaura cross-coupling reaction of sterically hindered aryl chlorides with low catalysts loadings (0.1 mol %) under mild conditions in air and good to excellent isolated yields of sterically hindered biaryls were obtained.

Synthesis of aryl-substituted quinolines and tetrahydroquinolines through Suzuki–Miyaura coupling reactions

The synthesis and characterization of substituted (trifluoromethoxy, thiomethyl, and methoxy) phenyl quinolines is described. Dichlorobis(triphenylphosphine)palladium(II)-catalyzed Suzuki–Miyaura cross-coupling of 6-bromo- and 6,8-dibromo-1,2,3,4-tetrahydroquinolines, 5-bromo-8-methoxyquinoline, and 5,7-dibromo-8-methoxyquinoline with substituted phenylboronic acids affords the corresponding 6-aryl- (13a–d), 6,8-diaryl- (14a–c), 5-aryl- (15), and 5,7-diaryl- (16b, c) tetrahydroquinolines and quinolines in high yields (68%–82%). The structures of all the products are characterized by 1H NMR, 13C NMR,19F NMR, and Fourier transform infrared spectroscopy and by elemental analysis.

Preparation and characterization of PEPPSI-palladium N-heterocyclic carbene complexes using benzimidazolium salts catalyzed Suzuki–Miyaura cross coupling reaction and their antitumor and antimicrobial activities

New palladium complexes were efficiently synthesized from the reaction of benzimidazolium salts 2a–e, potassium carbonate (K2CO3) and palladium chloride (PdCl2) in pyridine (for 3a–e). The catalytic activity of these complexes in a catalytic system including palladium complexes and K2CO3 in DMF-H2O was evaluated in Suzuki–Miyaura cross-coupling reactions of aryl bromides and chlorides with phenylboronic acid. Our novel complexes show excellent catalytic activities with high turnover numbers (TON) and high turnover frequencies (TOF) (e.g. for the Suzuki–Miyaura reaction: TON up to 370 and TOF up to 123.3 h−1). Both benzimidazolium salts 2a–e and complexes 3 have been characterized using spectroscopic data and elemental analysis. The antimicrobial activity of the N-heterocyclic carbene palladium complexes 3a–e varies with the nature of the ligands. Also, the IC50 values of both, complexes (3a–e) and benzimidazoles 2a–e, have been determined. In addition, the new palladium complexes were screened for their antitumor activity. Complexes 3e and 3d exhibited the highest antitumor effect with IC50 values 6.85 μg/mL against MCF-7 and 10.75 μg/mL against T47D, respectively.

Heterogeneous Suzuki-Miyaura coupling of heteroaryl ester via chemoselective C(acyl)-O bond activation.

A site-selective supported palladium nanoparticle catalyzed Suzuki–Miyaura cross-coupling reaction with heteroaryl esters and arylboronic acids as coupling partners was developed. This methodology provides a heterogeneous catalytic route for aryl ketone formation via C(acyl)–O bond activation of esters by successful suppression of the undesired decarbonylation phenomenon. The catalyst can be reused and shows high activity after eight cycles. The XPS analysis of the catalyst before and after the reaction suggested that the reaction might be performed via a Pd0/PdII catalytic cycle that began with Pd0.

Synthesis, characterization and photophysical properties of a new class of pyrene substituted 1,3,4-oxadiazole derivatives

We have designed and synthesized a series of a new class of pyrene substituted 1,3,4- oxadiazole derivatives (abbreviated as 3(a-e)) through palladium catalyzed Suzuki-Miyaura cross coupling reaction. The chemical structures of the probes were characterized by using analytical techniques namely 1H NMR, 13C NMR, FT-IR and GC-MS. The novel bipolar molecules consist of pyrene as an electron donor unit (D) and electron-deficient 1,3,4-oxadiazole as an acceptor unit (A) linked via extending π conjugation through a phenyl spacer with para linkages (D-π-A). Intramolecular charge transfer is improved by structure-property relationship. The detailed photophysical/solvatochromic properties of newly synthesized derivatives have been studied employing steady state spectroscopic techniques. The photophysical studies revealed that compounds emit strong indigo-blue fluorescence and efficient blue emission extending into blue-green in solid phase with high quantum yields. Thermal and morphological stabilities of the derivatives were studied employing DSC and TGA measurements. In addition, density functional theory (DFT) computations have been carried out to demonstrate various intramolecular interactions that cause the stabilization of the compound leading to its optoelectronic applications. The highest occupied molecular orbital energy (HOMOs), lowest unoccupied molecular orbital energy (LUMOs), the energy bandgap, chemical hardness (η), softness (δ), electronegativity (χ) and chemical potential (μ) were computed with the help of frontier molecular orbitals. The results were compared and discussed with the experimental results. The results demonstrate that the novel pyrene containing oxadiazole derivatives could be used as small organic molecules for multifunctional organic light-emitting devices (OLED)/optoelectronic devices.

Synthesis, crystal structure analysis, spectral IR, UV–Vis, NMR assessments, electronic and nonlinear optical properties of potent quinoline based derivatives: Interplay of experimental and DFT study

Quinoline and its derivatives are widely studied by both synthetic and computational chemists due to their exciting perspectives in biological and nonlinear optical (NLO) research. Herein, three novel arylated quinolines: 3-(4-acetylphenyl)quinoline (1), 3-(4-(methylthio)phenyl)-quinoline (2) and 3-(4-phenoxyphenyl)quinoline (3) were synthesized employing Pd catalyzed Suzuki–Miyaura cross-coupling reaction. The chemical structures of all compounds were resolved employing different analytical techniques like 1H-NMR, FT-IR, UV–Vis, EIMS, elemental analysis and finally confirmed by single crystal X-ray diffraction analysis. Synthesized compounds were further subjected to density functional theory (DFT) calculations at B3LYP level of theory in conjunction with 6-311 + G(2d,p) basis set to explore optimized geometry, natural bond orbital (NBO) analysis, FT-IR spectroscopic data, frontier molecular orbitals (FMOs) and NLO properties. Overall, a good agreement was found between DFT computed results and corresponding experimental findings. Vertical electronic transition states were computationally calculated using time-dependent DFT (TDDFT) at same B3LYP level of theory and 6-311 + G(2d,p) basis set combination. NBO calculations indicated the occurrence of intra-molecular charge transfer in synthesized compounds, hence enormous molecular stability owing to hyperconjugative interactions. Energy of FMOs was used to calculate the global reactivity descriptors which indicated that synthesized molecules are chemically hard compounds with greater kinetic stability and electron donating capability. NLO properties were found to be in the range 1830–2960 a.u and order of 2 > 1 > 3. Urea molecule comparative analysis and two-state model confirmed that synthesized molecules are excellent NLO candidates and may have prospective uses in the technology related applications.