Sonogashira Cross-coupling Reaction Research Articles

Synthesis of 4,5-disubstituted-1H-1,2,3-triazoles

Two-step procedure, a palladium catalyzed Sonogashira cross-coupling reaction of aroyl chlorides with aryl acetylenes, and 1,3-dipolar cycloaddition of the 1,3-diarylprop-2-yn-1-ones with sodium azide under catalyst free conditions achieved the synthesis of aryl(4-aryl-1H-1,2,3-triazol-5-yl)methanones in moderate-to-good chemical yields (30–90%). The procedures allowed the synthesis of 4,5-disubstituted-1H-1,2,3-triazol scaffolds containing electron-neutral, -withdrawing, or -donating groups.

Ligand Free Heterogeneous Sonogashira Cross-Coupling Reaction over an in Situ Organoiodine Capsulized Palladium Anchored to a Perovskite Catalyst

An environmentally friendly Sonogashira cross-coupling reaction is described in this study with high potential for application in a fluidized system. The LaCo0.9Ni0.05Pd0.05O3 perovskite based cata...

Pd@GO/Fe3O4/PAA/DCA: a novel magnetic heterogeneous catalyst for promoting the Sonogashira cross-coupling reaction

A hybrid system involving graphene oxide (GO), magnetic oxide (Fe3O4), acrylamide and dicyandiamide was prepared via amine functionalization of GO/Fe3O4 by means of covalent bonding with acrylamide and subsequent reaction with dicyandiamide to provide a multinitrogen containing polymer on the surface of GO. This hybrid system was utilized as a heterogeneous catalyst support for immobilizing Pd nanoparticles to provide the hybrid, Pd@GO/Fe3O4/PAA/DCA. This nano-Pd composite was characterized using Fourier transform infrared, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometer, thermogravimetric analysis, X-ray diffraction, and ICP techniques and used for promoting Sonogashira cross-coupling under mild reaction conditions. This heterogeneous and magnetic catalyst was easily separated by external magnet and was reused in a model reaction, efficiently up to six times with slight loss of catalytic activity and Pd leaching, showing the suitability of GO/Fe3O4/PAA/DCA for embedding Pd nanoparticles. To check the effect of the number of surface nitrogens of the polymeric chain on the catalytic performance, the activity of the catalyst was compared with Pd@GO/Fe3O4/PAA; increased number of the surface nitrogens on the chain polymer leads to higher loading of Pd and lower the Pd leaching.

Agro waste derived nanosilica supported Pd(ll) complex: A protocol for copper free Sonogashira reaction in water

A palladium (II) complex immobilized onto nanosilica(Pd-imine@nanoSiO2) has been developed and evaluated as a highly efficient, retrievable catalyst for carbon-carbon triple bond activation reactions between aryl halides and terminal alkynes. Nanosilica has been derived from rice husk by simple and eco-compatible methodology. The catalyst has been extensively characterized by techniques such as FT-IR, UV–vis, powder XRD, XPS, SEM-EDX, thermogravimetric analysis, BET surface area measurement. The catalyst can be reused for five consecutive runs without compromising much with the activity. Easy preparation, its long shelf life, air-stability, wide substrate scope, ‘in water’ reactions, easy separability and good recyclability make it an ideal system for Sonogashira cross-coupling reaction. Moreover, various alkyne substrates were efficiently cross-coupled with a broad range of aryl iodides and aryl bromides to afford diaryl alkynes, providing improved yields with low catalyst loading in water. This protocol is also suitable for aliphatic alkynes.

Synthesis and Functionalization of Ynone-Based Tubular Microporous Polymer Networks and Their Carbonized Products for CO2 Capture

Ynone-based microporous polymer networks (YMPNs) were synthesized by the reaction of aromatic dicarboxylic acid chloride and alkyne groups under Sono-gashira cross-coupling reaction conditions. As the reaction proceeded in a mixture of toluene and triethylamine (TEA), tubular precipitates formed rapidly. The microscopic and XRD studies showed thatthe precipitates had a core-shell structure with a rod-shaped triethylammonium chloride (TEA-HC1) crystalline core and a polymeric shell. The core was removed by washing with methanol to provide a hollow polymeric tube. The TEA-HC1 rod formed in situ during the cross-coupling reaction and served as a template in forming the tubular morphology. YMPNs could be modified with ease because of the presence of highly reactive ynone groups. YMPNs were functionalized with ethylenediamine by the Michael-type addition reaction. The amino group functionalized YMPNs were used as precursors of nitrogen-doped porous carbons. The pyrolysis of the polymers at 800 °C produced microporous carbon materials withoutthe activation process. The carbon materials showed significantly enhanced Brunauer-Emmett-Teller (BET) surface areas and CO2 uptake capacities compared to their precursor polymers.

Heterogeneous-phase Sonogashira cross-coupling reaction on COC surface for the grafting of biomolecules – Application to isatin

The grafting of 5-iodoisatin heterocycle on a cyclic olefin copolymer (COC) and a gold surface was performed using a heterogeneous phase Sonogashira reaction consisting of coupling 5-iodoisatin with an arylalkyne previously introduced onto the surfaces. This optimized strategy takes advantage of the well-established methodology to functionalize COC or gold surfaces using aryldiazonium surface chemistry. Herein, we reported the first example of an isatin decorated polymeric or metallic surface. The surfaces were analyzed with a combination of techniques such as IR (Infrared spectroscopy), XPS (X-Ray photoelectron spectroscopy) and SPR (surface plasmon resonance). Docking studies showed that isatin and two derivatives interact with AmiC, a dimeric protein produced by Pseudomonas aeruginosa. Bacterial adhesion on isatin−COC platform was also observed. This general strategy for robust surface functionalization represents an easy approach for patterning surfaces with compounds of biological interest, allowing access to a large panel of original biosensors.

Triptycene-Derived Photoresponsive Fluorescent Azo-Polymer as Chemosensor for Picric Acid Detection.

Two new triptycene-based azobenzene-functionalized polymers (TBAFPs) have been synthesized using the well-known Pd-catalyzed Sonogashira cross-coupling polycondensation reaction between 2,6-diethynyltriptycene and (meta or para) dibromo-azobenzenes. Enhancement of the fluorescent emission intensity was observed upon trans → cis isomerization of −N=N― linkage in TBAFPs. The cis-lifetime of TBAFP1 is rather long (greater than 2 days). The resulting materials were tested as a potential chemosensor for the detection of picric acid (PA)—a water pollutant as well as chemical constituent of explosives used in warfare. PA was found to interact strongly with TBAFPs, which led to significant quenching of the latter’s fluorescence emission intensities. The binding constants are in the order of 105 M–1. TBAFPs were also able to detect PA in nanomolar concentrations.

Novel 2-phenyl-6-phenylethynyl-4-(trifluoromethyl)quinolines: Synthesis by Sonogashira cross-coupling reaction and their evaluation as liquid crystals

This work reports the synthesis of a new series of 2-aryl-6-(phenylethynyl)-4-(trifluoromethyl) quinolines (2), where aryl = 4-(phenylethynyl)phenyl (2a), Ph (2b), 4-MeC6H4 (2c), 4-FC6H4 (2d). These were obtained by the Sonogashira coupling reaction producing 42–88% yield, utilizing 6-bromoquinolines and phenylacetylene as precursors in the presence of catalyst systems of Pd(OAc)2 and PPh3. The precursor 6-bromoquinolines were obtained from an intramolecular cyclisation reaction of (Z)-4-[(4-bromophenyl)amino]-1,1,1-trifluorobut-3-en-2-ones, which were previously prepared though the reaction of 4-methoxy-4-aryl-1,1,1-trifluoroalk-3-en-2-ones with 4-bromoaniline. Liquid crystal (LCs) properties were evaluated using thermal data and mesophase texture. Only compound 2a displayed monotropic nematic mesophase with very narrow liquid crystal window. Compounds 2b, 2c and 2d only displayed transition between the crystal phase to a liquid state. Nematic behavior was mainly dependent on the molecular length, as proved for 2a, which has the longest molecular length. Torsional angles between quinoline and aryl moieties at the 2-position were significant on hysteresis observed during the crystallization process.

Approach for Producing New 3,3,3-Trifluoropropenylation Reagents: Introduction of a 3,3,3-Trifluoroprop-1-enyl Group for Drug Development

The chemistry of the 3,3,3-trifluoroprop-1-enyl (TFPE) group has attractive characteristics in medicinal chemistry as a new fluorine motif. However, there are no reports on the properties of this group because it is difficult to construct molecules with it. For the convenient construction of the TFPE group, a new fluorination reagent, CF3CH=CHTMS (1), was developed from commercially available chemicals with easy purification processes and excellent yields. The utility of 1 as a trifluoropropenylation reagent was exhibited in several types of reaction such as the Sonogashira cross-coupling reaction. Furthermore an indometacin analogue bearing a TFPE group showed greater pharmaceutical activity than the original indometacin. This review describes the details of these research studies under three topics: 1) synthesis of 1; 2) Sonogashira cross-coupling reaction of 1 with acetylene, followed by cyclization into an indole ring; and 3) synthesis of an indometacin analogue with a TFPE group.

Sonogashira cross-coupling in iodo-containing 2-aryloxazolines

Aryloxazolines represents potential building blocks in the synthesis of precursors of ESIPT-active sensors. Here we describe the Sonogashira cross-coupling reaction between iodo-containing 2-aryloxazolines and terminal alkynes. The reaction occurs under mild conditions and a range of alkynes was employed leading the formation of a small library of functionalized aryloxazolines.

Synthesis of triptycene-derived covalent organic polymer networks and their subsequent in-situ functionalization with 1,2-dicarbonyl substituents

Three-dimensional polymer derivatives TP1–4 containing triptycene comonomers were synthesized from 1,4-diethynyl triptycene 1 with various di-, tri-, and tetra-brominated aromatic building blocks 3a-d through the mild Sonogashira cross-coupling reaction conditions. The abovementioned alkyne-containing copolymers were subsequently oxidized into their respective 1,2-diketone derivatives, OTP1–4, under mild reaction conditions. The UV–Vis and emission studies of copolymers TP1–4 and their oxidized homologues OTP1–4 confirmed the major influence of the aromatic substituent on the copolymer conjugation. Thermogravimetric analysis of copolymers TP1–4 revealed relatively high 10% weight loss temperature values (Td) reaching up to 490 °C. On the other hand, the 1,2-diketone containing target polymers OTP1–4 showed lower 10% weight loss temperature values Td, with a maximum of 431 °C.

Synthetic Approaches to Star-Shaped Molecules with 1,3,5-Trisubstituted Aromatic Cores.

Herein, we summarize the synthetic approaches that have been developed for the synthesis of star-shaped molecules. Typically, to design such highly functionalized molecules, simple building blocks are first assembled through trimerization reactions, starting from commercially available starting materials. Then, these building blocks are synthetically manipulated to generate extended star-shaped molecules. We also discuss the syntheses of star-shaped molecules that contain 2,4,6-trisubstituted 1,3,5-triazine or 1,3,5-trisubstituted benzene rings as a central core and diverse substituted styrene, phenyl, and fluorene derivatives at their periphery, which endows these molecules with extended conjugation. A variety of metal-catalyzed reactions, such as Suzuki, Buchwald-Hartwig, Sonogashira, Heck, and Negishi cross-coupling reactions, as well as metathesis, have been employed to functionalize a range of star-shaped molecules. The methods described herein will be helpful for designing a wide range of intricate compounds that are highly valuable in the fields of supramolecular chemistry and materials science. Owing to space limitations, we will not cover all of the publications on this topic. Instead, we will focus on examples that were reported by our research group and other relevant recent literature. Apart from the trimerization sequence, this Minireview has been structured based on the key reactions that were used to prepare the star-shaped molecules and other higher analogues. Finally, some examples that do not fit into this classification are discussed.

Stereoselective Synthesis of (Z)-2-Bromo-2-CF3-Vinyl Phenyl Sulfide and its Sonogashira Cross-Coupling Reaction

A practical synthesis of (Z)-2-bromo-2-CF3-vinyl phenyl sulfide from 2-CF3-vinyl phenyl sulfide was achieved using bromine (Br2) in the presence of LiBr and LiOAc in AcOH in one flask. This method affords a stereodefined product in high yield under mild conditions. The synthetic application of the product was briefly examined, providing a wide range of Sonogashira cross-coupling products using terminal acetylenes as a coupling partner.

Homocoupling defects in porphyrinoid small molecules and their effect on organic solar cell performance

Abstract Porphyrinoid small molecules can be used as electron donor or acceptor components in bulk heterojunction organic solar cells, which has resulted in steadily improving power conversion efficiencies. However, the effect of material purity is often neglected. In this work, a series of D1-A-π-D2-π-A-D1 conjugated chromophores based on the A2B2-meso-ethynylporphyrin core is synthesized. Different electron-donating (D1) end groups are chosen to investigate their influence on the material properties and optoelectronic characteristics. The porphyrin small molecules are tested as electron donor materials in bulk heterojunction organic solar cells in combination with PC71BM, affording an efficiency up to 4.6% under standard illumination. Furthermore, it is shown that (Glaser type) homocoupled side products are generated during the final Sonogashira cross-coupling reactions, which can be very challenging to remove. Their presence reduces solar cell performance by affecting the open-circuit voltage and fill factor.

Transition metal- and oxidant-free sulfonylation of 1-sulfonyl-1H-1,2,3-triazoles to enols for the synthesis of sulfonate derivatives

A novel and convenient protocol for the synthesis of sulfonate derivatives via DABCO-catalyzed direct sulfonylation of 1-sulfonyl-1,2,3-triazoles to different enols has been established. This synthetic route could effectively avoid the use of transition metal catalysts and extra oxidants, and the target products could be obtained in good to excellent yields (75-86%) with wide substrate scope under mild conditions at low-catalyst loadings, which would provide a facile and practical access to enol sulfonates. Furthermore, the use of the resulting enol sulfonates for the C-C bond formation has been demonstrated via Suzuki-Miyaura, Sonogashira, and Heck cross-coupling reaction.

Solvent-Dependent Nanostructures Based on Active π-Aggregation Induced Emission Enhancement of New Carbazole Derivatives of Triphenylacrylonitrile.

In the present study, the carbazole and 2,3,3-triphenylacrylonitrile (TPAN) nanostructures (2-CTPAN and 2,2'-CTPAN) have been designed and synthesized by Pd-catalyzed Sonogashira cross-coupling reaction. CTPAN exhibit aggregation-induced emission enhancement (AIEE) behavior in water with high fluorescence quantum yield. Both the compounds show tunable self-assembly in water as well as in N,N-dimethylformamide (DMF) by extended π-π stacking interactions. CTPAN can be self-assembled into spherical particles in water and the structures of these self-assemblies have been investigated using X-ray diffraction. Interestingly, 2-CTPAN and 2,2'-CTPAN form organogels with a critical gelation concentration (CGC) of 11 and 15 mg mL-1 , respectively, in DMF and exhibit acicular and rod shaped morphology, respectively. The single-crystal structure of 2-CTPAN shows that the intermolecular C-H⋅⋅⋅π interactions lock the molecular conformation into a staircase-shaped supramolecular assembly. These AIEE active compounds reveal high water dispersibility, strong yellow fluorescence with high quantum yield, promising photostability and excellent biocompatibility, which make them potential bioimaging agents.

Design and Synthesis of a Novel Banana-Shaped Functional Molecule via Double Cross-Coupling.

A novel banana-shaped molecule using 2,8-Dimethyl-6H,12H-5,11-methanodibenzo [b,f] [1,5]diazocine (Tröger’s base) as bent-core was synthesized via double Carbon-Carbon cross-coupling reaction. The double Sonogashira cross-coupling reaction was optimized by using Pd(PPh3)2Cl2 as catalyst, CuI as cocatalyst and diisopropylamine as base in place of triethylamine. The structure of this compound was confirmed by 1H-NMR, 13C-NMR, Fourier transform infrared (FT-IR) spectroscopy and mass spectrometry.

Effect of Substrates on Catalytic Activity of Biogenic Palladium Nanoparticles in C-C Cross-Coupling Reactions.

This work describes a practical methodology for C–C bond formation reactions with the aid of biogenic palladium nanoparticles, which are synthesized by using phytochemicals extracted from two common plant species. Comparative studies have been done on the activity of two plant species (Ocimum sanctum and Aloe vera) in generation of palladium nanoparticles via ex situ and in situ methods. The structural and morphological characteristics of the nanoparticles are examined by UV/visible spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy analyses. We have observed a significant influence of the substrates on the catalytic activity of the palladium nanoparticles in Sonogashira and Suzuki cross-coupling reactions.

Electronic Coupling in π-Conjugated Molecule-Bridged Silicon Quantum Dot Clusters Synthesized by Sonogashira Cross-Coupling Reaction.

π-Conjugated molecule-bridged silicon quantum dot (Si QD) clusters were first synthesized by Sonogashira cross-coupling reaction between 4-ethynylstyryl and octyl co-capped Si QDs (4-Es/Oct Si QDs) and 2,5-dibromo-3-hexylthiophene. The formation of Si QD clusters was confirmed by field emission transmission electron microscopy. The electronic coupling between the QDs in the Si QD cluster is significantly enhanced as compared with that for 4-Es/Oct Si QDs, which is verified from the red shift in ultraviolet–visible absorption and photoluminescence spectra of the Si QD cluster with the possibility of exciton transport, the increased charging effect found in the core-level photoemission spectra, the shift to lower binding energy of the valence band photoemission spectrum, and more decisively, the increase in electrical conductance of the Si QD cluster thin film. To investigate the physical origin of the temperature dependence of the electrical conductance, we have merged the microscopic viewpoint, Marcus theory, on the electron transfer (W) between the adjacent QDs, with macroscopic concepts, such as the conductance (G), mobility (μ), and diffusion coefficient (D). The effective reorganizational energies of charge transfer between the neighboring Si QDs in 4-Es/Oct Si QD and Si QD cluster thin films are estimated to be 170 and 140 meV, respectively, while the ratio of the effective electronic coupling of the latter to that of the former is determined to be 7.3:1.

Functionalized graphene oxide anchored to Ni complex as an effective recyclable heterogeneous catalyst for Sonogashira coupling reactions

The Sonogashira cross coupling reaction is an applied method for preparation of diarylethyne compounds from readily available aryl halide derivatives and phenyl acetylene. The coupling reaction using nickel complex of N,N′-Bis(2-hydroxyethyl)ethylenediamine onto core shell graphene oxide (GO@SiO2-BHED-Ni) as a catalyst was studied in this research. This heterogonous catalyst showed good thermal stability, highly efficiency and recyclability in the reaction. Moreover, the catalyst is simply separated and can be reused several times without significant loss of catalytic activity. A wide range of aryl halides was coupled successfully under palladium and phosphine free conditions. The use of this catalyst led to the formation of substituted aromatic alkynes in excellent yields and short reaction times.