Sonogashira Cross-coupling Reaction Research Articles

Synthesis of pyrene-centered D-π-a structured dyes for efficient dye-sensitized solar cells

An asymmetric pyrene derivative was designed as a dye with D-π-A structure. This dye was synthesized by the following steps (acylation reaction, Friedele Crafts acylation reaction, bromination reaction, Hagiharae Sonogashira cross-coupling reaction, and knoevenagel condensation reactions). The structure of the dye was analyzed and identified by FT-IR and 1H-NMR. The dye-sensitized solar cells were prepared with the dye and TiO2 electrode. Futhermore, the I-V curves and IPCE curves of the dye-sensitized solar cells were investigated detailedly. The result showed that the photoelectric conversion efficiency of the dye-sensitized solar cells reached 33.5% of N719 dye cells.

Nickel-palladium bimetallic nanoparticles supported on multi-walled carbon nanotubes; versatile catalyst for Sonogashira cross-coupling reactions.

We have developed an efficient method to generate highly active nickel-palladium bimetallic nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) by dry mixing of the nickel and palladium salts utilizing the mechanical energy of a ball-mill. These nanoparticles were successfully employed in Sonogashira cross-coupling reactions with a wide array of functionalized aryl halides and terminal alkynes under ligand and copper free conditions using a Monowave 50 heating reactor. Notably, the concentration of palladium can be lowered to a minimum amount of 0.81% and replaced by more abundant and less expensive nickel nanoparticles while effectively catalyzing the reaction. The remarkable reactivity of the Ni-Pd/MWCNTs catalyst toward Sonogashira cross-coupling reactions is attributed to the high degree of the dispersion of Ni-Pd nanoparticles with small particle size of 5-10 nm due to an efficient grinding method. The catalyst was easily removed from the reaction mixture by centrifugation and reused several times with minimal loss of catalytic activity. Furthermore, the concentration of catalyst in Sonogashira reactions can be reduced to a minimum amount of 0.01 mol% while still providing a high conversion of the Sonogashira product with a remarkable turnover number (TON) of 7200 and turnover frequency (TOF) of 21 600 h-1. The catalyst was fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).

Metal phosphine aldehyde complexes and their application in Cu-free Sonogashira and Suzuki-Miyaura cross-coupling reactions.

Transition metal coordination chemistry and catalysis are rife with phosphine ligands. One of the rather less studied members of the phosphine ligand family are phosphine aldehydes. We have synthesised 3-(diphenylphosphino)propanal (PCHO) with a slight modification of the known procedure and studied its complexation behaviour with palladium(II) and platinum(II). The catalytic activity of the palladium(II) phosphine aldehyde complexes was investigated in Cu-free Sonogashira and Suzuki-Miyaura cross-coupling reactions. Furthermore, the homogeneous nature of the catalytically active species was confirmed.

Effects of donor and acceptor substituents on the photophysics of 4-ethynyl-2,1,3-benzothiadiazole derivatives.

The present work explores the photophysical, electrochemical, and fluorescence polarization properties of a group of π-conjugated phenylethynyl-2,1,3-benzothiadiazole derivatives (BTDs) bearing different electron-donating (ED) or electron-withdrawing (EW) substituents at the para position of the phenylethynyl moiety. The BTDs were synthesized through the Sonogashira cross-coupling reaction between 4-bromo-2,1,3-benzothiadiazole and the respective para-substituted phenylethynyl derivatives. The BTDs with the EW-substituents show relatively weak solvatochromic behavior, while the BTDs with the strong ED-substituents like methoxy and N,N-dimethylamino-based substituents (BTDPhOMe and BTDPhNMe2) exhibit a pronounced solvatochromic behavior. The change in dipole moments in the excited states of the derivatives was calculated using Lippert-Mataga plots. The conclusions drawn on the spectral behavior of the molecules could be rationalized by TD-DFT calculations involving electron density difference (EDD) maps that correlate with the ICT characteristics of the molecules. The experimental and theoretical calculations reveal that the BTDs with the strong ED-substituents (strong push-pull type BTDs) have a strong ICT character in the excited state. These strong push-pull type BTDs show high fluorescence quantum yield (ΦF) in apolar solvents and low ΦF in polar solvents. In contrast, the BTDs with the weak ED-substituents (weak push-pull type BTDs) and EW-substituents (pull-pull type BTDs) have a weaker ICT character with low ΦF in apolar and high ΦF in polar solvent media. There is good a agreement among the HOMO-LUMO band gaps obtained from absorption spectroscopy and electrochemical studies and theoretical calculations. The fluorescence anisotropy measurement in the glycerol medium shows that the studied BTDs generally exhibit higher sensitivity towards microviscosity than the traditional DPH fluorescence anisotropy probe.

Influence of bridge structure manipulation on the electrochemical performance of π-conjugated molecule-bridged silicon quantum dot nanocomposite anode materials for lithium-ion batteries.

To assess the influence of bridge structure manipulation on the electrochemical performance of π-conjugated molecule-bridged silicon quantum dot (Si QD) nanocomposite (SQNC) anode materials, we prepared two types of SQNCs by Sonogashira cross-coupling and hydrosilylation reactions; one is SQNC-VPEPV, wherein the Si QDs are covalently bonded by vinylene (V)-phenylene (P)-ethynylene (E)-phenylene-vinylene, and the other is SQNC-VPV. By comparing the electrochemical performances of the SQNCs, including that of the previously reported SQNC-VPEPEPV, we found that the SQNC with the highest specific capacity varied depending on the applied current density; SQNC-VPEPV (1420 mA h g-1) > SQNC-VPV (779 mA h g-1) > SQNC-VPEPEPV(465 mA h g-1) at 800 mA g-1, and SQNC-VPV (529 mA h g-1) > SQNC-VPEPEPV (53 mA h g-1) > SQNC-VPEPV (7 mA h g-1) at 2000 mA g-1. To understand this result, we performed EIS and GITT measurements of the SQNCs. In the course of investigating the lithium-ion diffusion coefficient, charge/discharge kinetics, and electrochemical performance of the SQNC anode materials, we found that electronic conductivity is a key parameter for determining the electrochemical performance of the SQNC. Two probable causes for the unique behavior of the electrochemical performances of the SQNCs are anticipated: (i) the SQNC with predominant electronic conductivity is varied depending on the current density applied during the cell operation, and (ii) the degree of surface oxidation of the Si QDs in the SQNCs varies depending on the structures of the surface organic molecules of the Si QDs and the bridging molecules of the SQNCs. Therefore, differences in the amount of oxides (SiO2)/suboxides (SiOx) on the surface of Si QDs lead to significant differences in conductivity and electrochemical performance between the SQNCs.

3D printing of a palladium-alumina cermet monolithic catalyst: catalytic evaluation in microwave-assisted cross-coupling reactions

A straightforward manufacture strategy is proposed to obtain an efficient and robust palladium-alumina (Pd0/Al2O3) cermet monolithic catalyst, specifically designed to perform safe microwave assisted organic synthesis (MAOS). In this approach, a cermet catalyst with high surface area, controlled composition and adapted shape and dimensions to a microwave reactor vessel is generated via 3D printing technology and sintering. The resulting catalyst has been explored in heterogeneous Suzuki, Sonogashira, Stille and Heck cross-coupling reactions, in MAOS. The Pd0 catalyst is permanently active, stable, without leaching and can be recycled and reused at least 200 reaction cycles. The generation of hot spots, sparking or hazardous discharges is controlled by the effective immobilization of the palladium in the monolithic structure during the reaction. The palladium content is forming part of both the internal and external structure, providing greater mechanical resistance and catalytic activity with respect to the basic ceramic material (alumina).

Application of hindered ether solvents for palladium catalyzed Suzuki-Miyaura, Sonogashira and cascade Sonogashira cross-coupling reactions.

Cross-coupling and cascade reactions typically rely on unsustainable and toxic volatile organic solvents. 2,2,5,5-Tetramethyloxolane (TMO) and 2,5-diethyl-2,5-dimethyloxolane (DEDMO) are both inherently non-peroxide forming ethers, and have been used in this work as effective, more sustainable, and potentially bio-based alternative solvents for Suzuki-Miyaura and Sonogashira reactions. Suzuki-Miyaura reactions demonstrated good yields for a range of substrates, 71-89% in TMO and 63-92% in DEDMO. In addition, a Sonogashira reaction exhibited the excellent yields of 85-99% performed in TMO, which was significantly higher than traditional volatile organic solvents, THF or toluene, and higher than those reported for another non-peroxide forming ether, namely eucalyptol. Cascade Sonogashira reactions utilizing a simple annulation methodology were particularly effective in TMO. Furthermore, a green metric assessment confirmed that the methodology employing TMO was more sustainable and greener than the traditional solvents THF and toluene, thereby demonstrating the promise of TMO as an alternative solvent for Pd-catalyzed cross-coupling reactions.

Chemometric tools for kinetic investigations of a homogeneously catalysed Sonogashira cross-coupling reaction in flow

A chemometrics-based approach for process optimisation of a chemical reaction in an automated microreactor flow setup and performing kinetic investigations.

Solid-Supported Heterogenized Palladium Nanoparticles: Propitious Vehicles for Sonogashira Cross-Coupling Reaction

Abstract

Total Synthesis, Absolute Configuration, and Phytotoxic Activity of Foeniculoxin.

Foeniculoxin is a major phytotoxin produced by Italian strains of Phomopsis foeniculi. The first total synthesis is described utilizing the ene reaction and Sonogashira cross-coupling reaction as key steps. The absolute configuration of the C6' was determined using chiral separation and an advanced Mosher's method. The phytotoxicity of the synthesized compound was demonstrated via syringe-based infiltration into Chenopodium album and Arabidopsis thaliana leaves. Synthetic foeniculoxin induced various defects in A. thaliana leaf cells before lesion formation, including protein leakage into the cytoplasm from both chloroplasts and mitochondria and mitochondrial rounding and swelling. Furthermore, foeniculoxin and the antibiotic hygromycin B caused similar agglomeration of mitochondria around chloroplasts, highlighting this event as a common component in the early stages of plant cell death.

Cu-Ce Bimetallic Metal-Organic Framework-Derived, Oxygen Vacancy-Boosted Visible Light-Active Cu2O-CeO2/C Heterojunction: An Efficient Photocatalyst for the Sonogashira Coupling Reaction.

The development of an economical transition metal-based catalyst for photocatalytic carbon-carbon coupling reactions is aspiring. Herein, a Cu-Ce metal-organic framework (MOF) was synthesized and carbonized to produce bimetallic Cu2O-CeO2/C, which was utilized in the Sonogashira cross-coupling reaction. The defects and oxygen vacancies in the catalyst were characterized by X-ray photoelectron spectroscopy and Raman spectroscopy, while the nature of Cu was characterized by H2-TPR analysis. The defect-induced MOF-derived Cu-Ce heterojunction created more oxygen vacancies (OV) in CeO2, revealing the high photocatalytic activity. The Cu-Ce heterojunction (Cu2O-CeO2/C) formed a Cu(I)-phenylacetylide active complex and exhibited higher catalytic activity for the visible light-induced Sonogashira cross-coupling reaction. 25%Cu2O-CeO2/C offered 93.8% phenylacetylene conversion with a 94.2% Sonogashira product selectivity by using household light-emitting diodes. No discernible activity loss was observed from the recycling of the catalyst. Based on catalytic activity, control reactions, and physicochemical and optoelectronic characterization, the structure-activity relationship was established and a reaction mechanism was proposed. Replacement of the costly Pd metal-based catalyst with a cheap Cu2O-CeO2-based catalyst for the synthesis of commercially important compounds with a sustainable visible light-induced catalytic process will be highly attractive to chemists and industrialists.

Cyano-rich donor-acceptor-donor-type NLOphores containing dialkylated triazene and aniline groups

Continuous progress on the synthesis of push-pull chromophores is related to their outstanding optoelectronic properties. Expanding scope is a challenge due to the instability of targets and long synthetic strategies. Herein, we report the synthesis of thirteen different triazene-substituted alkyne substrates using Sonogashira cross-coupling reactions. Although we have previously described successful syntheses of homoconjugated and π-conjugated push-pull systems starting from triazene-substituted terminal alkynes, symmetric and unsymmetric bis-triazenes that we reported in this study unexpectedly did not undergo [2 + 2] cycloaddition-retroelectrocyclizations (CA-RE) with well-known electron acceptors, TCNE and TCNQ. With the use of diethylaniline-substituted substrates in CA-RE, this issue was successfully circumvented. Two different groups of NLOphores were synthesized in very high yields via [2 + 2] CA-RE with TCNE (95–99%) and TCNQ (92–99%). All target NLOphores were investigated by UV/Vis spectroscopy, thermal gravimetric analysis, high-resolution mass spectrometry, theoretical studies, and EFISHG experiments. While different dialkyltriazene groups did not appear to have an important impact on ICT properties of the chromophores, modifications made in the electron withdrawing units significantly affected the ICT performance of the chromophores. Target push–pull-systems displayed λmax values for their CT bands ranging between 454 and 692 nm. The ICT properties of the chromophores were confirmed by computational studies (Time-dependent density functional theory (TD-DFT) studies, frontier orbital visualizations, electrostatic potential maps, and calculation of several parameters such as dipole moment, HOMO-LUMO gaps, electronegativity, global chemical hardness, and softness, average polarizability, first hyperpolarizability) as well as experimental UV/Vis studies. As computational studies indicate that synthesized chromophores are potential NLOphores, experimental NLO measurements were performed by the EFISHG technique. Target structures exhibited large NLO responses (μβ values ranging 850 × 10−48 esu to 6050 × 10−48 esu).

A Cascade Sonogashira Cross-Coupling-Substitution-Elimination Reaction for the Synthesis of Linear Conjugated Dienynes.

The engagement in tandem of well-known organic reactions such as the Pd-catalyzed Sonogashira cross-coupling reaction, nucleophilic substitution and elimination reactions, enables the synthesis of otherwise difficult to obtain linear dienynes, in moderate to high yields. This retrosynthetic approach opens new ways to prepare highly conjugated alkenes and alkynes. Furthermore, ionic liquids are suitable solvents to perform the cascade reaction and recycle the metal catalysts.

Copper adorned magnetic nanoparticles as a heterogeneous catalyst for Sonogashira coupling reaction in aqueous media

A nanomagnetic hydrophilic heterogeneous copper catalyst, termed γ-Fe2O3@PEG@PAMAM G0-Cu, has been successfully prepared and characterized using FT–IR, XRD, FE-SEM, TEM, EDX, mapping, TGA/DTG, VSM and ICP analyses. The catalyst displayed excellent activity for the palladium-free Sonogashira cross coupling reaction of various aryl iodides and bromides with phenylacetylene derivatives in pure water. The presence of polyethylene glycol coupled with hydrophilic character of the Cu-catalyst adorned on γ-Fe2O3 MNPs provides the ready dispersion of the catalyst particles in water, leading to higher catalytic performance as well as facile catalyst recovery via simple magnetic decantation. The recovered catalyst was reused for at least six successive runs with little reduction in its catalytic activity and any noticeable changes in its structure. The use of water as a green solvent, without requiring any additive or organic solvent, as well as the exploitation of abundant and low-cost copper catalyst instead of expensive Pd catalyst along with the catalyst recovery and scalability, make this method favorable from environmental and economic points of view for the Sonogashira coupling reaction.

The construction of conjugated organic polymers containing phenanthrenequinone redox centers for visible-light-driven H2O2 production from H2O and O2 without any additives

Photocatalytic preparation of hydrogen peroxide (H2O2) by visible light irradiation is a promising approach to achieve the conversion of solar-to-chemical energy. But it still faces a huge challenge with the development of efficient and environmentally friendly catalytic system which is applied to H2O2 production from H2O and O2 without any additives. Hereby, we present a conjugated organic polymer (PQTEE-COP) by Sonogashira cross-coupling reaction between 2,7-dibromophenanthrenequinone (PQ) with 1,1,2,2-tetrakis(4-ethynylphenyl)ethene (TEE), which contains phenanthrenequinone redox centers and can efficient photocatalysis the production of H2O2 from H2O and O2 without any additives. The extended two-dimensional π-conjugated framework with electron-donor tetrakis(4-ethynylphenyl)ethene and electron-acceptor phenanthrenequinone moieties can not only improve visible light harvesting, but also accelerate photo-induced charges separation and migration. In addition, the phenanthrenequinone moieties can serve as redox centers to accept photo-induced electrons and transfer to adsorbed O2 molecule for subsequent H2O2 production through electron-coupled hydrogenation reaction (PQ to PQH2). The PQTEE-COP exhibits efficient photocatalytic production of H2O2 with initial rate of 3009 μmol g-1h−1 from H2O and O2 under visible light (λ ≥ 400 nm) irradiation without any additives. This work provides a scheme for the rational design of conjugated organic polymer based materials for efficient solar-to-chemical energy conversion.

Regiochemically Pure 1,6-Ditriflato-Perylene Diimide: Preparation and Transformation.

Preparation of regioisomerically pure 1,6-disubstituted perylene diimide (PDI) is not a trivial task owing to the lack of facile synthetic and separation methodologies for the precursors. Herein, we present a simple synthesis for 1,6-ditriflato-PDI (1,6-diOTf-PDI) using 1,6,9,10-tetrabromo-perylene monoimide 1 as the starting material. The selective methoxylation of 1 at the 1,6-position is the key step. Based on a four-step sequence of selective methoxylation, domino carbonylative amidation, demethylation, and triflation, 1,6-diOTf-PDI can be obtained in a satisfactory yield. Moreover, as a building block, 1,6-diOTf-PDIa can readily undergo Suzuki and Sonogashira cross-coupling reactions.

Cobalt nanoparticle adorned on boron- and nitrogen-doped 2D-carbon material for Sonogashira cross-coupling reactions: Greener and efficient synthesis of anti-cancer drug, Ponatinib

Herein, a novel heterogeneous cobalt catalyst was synthesized, characterized and its efficiency in Sonogashira cross-coupling reaction was investigated. Nano cobalt species dispersed on a graphene-like carbonaceous 2D network comprising nitrogen and boron atoms sites, were produced by synthesizing of NHC-cobalt complex followed by 2D metal-organic hybrid preparation and a high-temperature pyrolysis in the final step. A combination of assorted analytical techniques like TEM, XRD, EA, ICP, and XPS studies endorsed the structure of the catalyst. This catalyst exhibited unprecedented efficiency in Pd-free coupling of various substituted challenging heterocyclic acetylenes and aryls. In addition to sustainable and green reaction conditions, the catalytic system displayed the brilliant feature of stability and reusability even after 12 runs. Finally, we used this catalytic system in the synthesis of Ponatinib in fewer steps and at much lower costs than available commercial synthesis methods; Ponatinib is a recently FDA-approved multi-tyrosine kinase inhibitor, anti-sarcomas cancer agent, and a drug for common neurodegenerative diseases.

Stereoselective Reduction of Alkynes: Synthesis of 4-Organoselenyl Quinolines.

This study describes the reaction of 2-amino arylalkynyl ketones with organoselenolates to form (Z)-vinyl selenides, which lead to 4-organoselenyl quinolines via an intramolecular condensation. Using the optimized reaction conditions, the generality of this cyclization was studied with various arylalkynyl ketones and diorganyl diselenides. The study of the reaction mechanisms led to the isolation and identification of a vinyl selenide, which was the key intermediate for this cyclization. To expand the structural diversity and to demonstrate the applicability of the 4-organoselenyl quinolines prepared, we studied their application as substrates in the cleavage of the carbon-selenium bond using n-butyllithium followed by the capture of the lithium intermediate by electrophiles and Suzuki and Sonogashira cross-coupling reactions.

Structural characterization of ((9-fluorenylidene) (ferrocenyl)methyl)palladium iodide as the catalytic intermediate in the synthesis of 9-(ferrocenyl (ferrocenylethynyl)methylene)-9H-fluorene

The reaction of 2,2′-diiodo-1,1′-biphenyl (1a) with ethynyl ferrocene (2) gave trace amounts of the expected 2,2′-bis(ferrocenylethynyl)-1,1′-biphenyl (3) together with 9-(ferrocenyl(ferrocenylethynyl)methylene)-9H-fluorene (4), formed via a cyclization process during the Sonogashira cross-coupling reaction, as the major product. In contrast, a similar reaction of the 2,2′-diiodo-1,1′-diphenyl ether analogue with 2 gave the anticipated 2,2′-bis(ferrocenylethynyl) substituted product (11). Reaction of 11 with tetracyanoethylene gave its bis-[2 + 2] cycloaddition product in high yield (12), while the alkynyl motif in fluorenylidene 4 proved to be inert towards such reactions. Studies of the mechanism leading to formation of 4 using a Pd/dppf (dppf = 1,1′-bis(diphenylphosphino)ferrocene) catalyst combination allowed for isolation of a {C = C(Fc)–PdI(dppf)} intermediate (13), which was structurally characterized by single crystal X-ray diffraction. Electrochemical investigations of 4, 11, 12 and 13 revealed a series of essentially ferrocene-based oxidation processes, which in the case of 4 and 11 could be better resolved using a non-coordinating anion based electrolyte. Electronic structure studies at the DFT level (B3LYP/def2-TZVP/CPCM(CH2Cl2) suggest that the first oxidation event in 4 can be assigned to the vinyl-bonded ferrocenyl moiety.

A novel and efficient magnetically recoverable copper catalyst [MNPs-guanidine-bis(ethanol)-Cu] for Pd-free Sonogashira coupling reaction

We designed and fabricated a copper complex immobilized on the surface of silica-coated magnetic nanoparticles modified with guanidine-bis ethanol (prepared via the ring-opening reaction of MNPs-guanidine with epoxide). FT-IR spectroscopy, Scanning electron microscope (SEM, Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), Thermogravimetric analysis (TGA), Vibrating sample magnetometer (VSM), X-ray diffraction (XRD), Elemental mapping, Atomic absorption spectroscopy (AAS), Inductively Coupled Plasma Optical Emission spectroscopy (ICP-OES) and Elemental mapping-analysis were used to characterize the structure of MNPs-guanidine-bis(ethanol)-Cu nanocatalyst. The MNPs-guanidine-bis(ethanol)-Cu nanocomposite showed high catalytic activity in the Pd-free Sonogashira cross-coupling reactions. The MNPs-guanidine-bis(ethanol)-Cu catalyst was consistent toward a variety of aryl halides bearing amine, acid, aldehyde, nitro, etc., functional groups, where high-to-excellent yields were obtained for all substrates. The copper nanocatalyst could be easily recovered by a simple magnetic separation and recycled at least 8 times without deterioration in catalytic activity.