Phenylacetylene Derivatives Research Articles

Preparation of a magnetic copper NNN pincer complex as an efficient catalyst in the synthesis of 4-(phenylethynyl) and 4-(4-phenyl-1H-1,2,3-triazol-5-yl)coumarin derivatives

In this study, a 3-amino-trimethoxysilane-modified magnetic support was prepared and functionalized with furan-2-carbohydrazide through 2,4,6-trichloro-1,3,5-triazine as an organic linker to form a nitrogen rich pincer type ligand for copper coordination. The structure and morphology of the prepared nanocomposite (Fe3O4@SiO2-FCH (NNN pincer)/Cu) was confirmed with various techniques including FT-IR, FE-SEM, VSM, TEM, ICP, XRD, and EDX analysis. The amount of Cu in the nanocomposite was determined to be 9.9%wt. Then, its application in the synthesis of 4-(phenylethynyl)coumarin derivatives through CC bond formation between substituted 4-hydroxycoumarin and phenylacetylene derivatives was evaluated. After functionalizing of 4-position in 4-hydroxycoumarins with phenylacetylene derivatives, sodium azide was added and substituted 4-triazole-coumarins were synthesized in the presence of low amount of Fe3O4@SiO2-FCH (NNN pincer)/Cu nanocatalyst. The nanocatalyst was easy separated using of an external magnet and reused at least four run without reduction in its activity.

高分子末端の構造を自由に設計できる一置換アセチレン類の精密重合法の開発

Substituted polyacetylene derivatives are promising π-conjugated materials, which can be synthesized by polymerization of the corresponding substituted acetylenes by transition metal catalysis. Rhodium(I) complexes have been widely used for the polymerization of monosubstituted acetylenes such as phenylacetylene derivatives because they are functional group tolerant and provide cis-stereoregular polymers. There are some examples of well-controlled polymerization of phenylacetylene derivatives using well-defined rhodium(I) complexes as initiators. However, versatile design of polymer end structures is difficult in such known methods because initiators having various functional groups are not easily available. To overcome such a problem, we have developed a new method for well-controlled polymerization of phenylacetylene derivatives using a multicomponent catalytic system composed of bicyclo[2.2.1]hepta-2,5-diene-rhodium(I) chloride dimer [Rh(nbd)Cl]2, arylboronic acids, diphenylacetylene and 50% aqueous solution of KOH. This polymerization method showed a typical living nature, and structures derived from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the obtained polymers. Moreover, functionalization of the polymer terminal end could be achieved by reactions of the living polymer terminus with α,β-unsaturated carbonyl compounds such as acrylates, and various telechelic poly(phenylacetylene)s were obtained. Novel 1,3,5-hexatrienylrhodium(I) complexes were isolated from the present multicomponent catalytic system, and their structures were identified. When [Rh(nbd)Cl]2 was replaced with hydroxy(1,5-cyclooctadiene) rhodium(I) dimer ([Rh(cod)OH]2) in the present catalytic system, cyclobutenylrhodium(I) complexes were exclusively obtained. These complexes provided insights into the initiation mechanism in the living polymerization. The present catalytic system was applied to the living polymerization of water-soluble phenylacetylene derivatives and non-conjugated monosubstituted acetylenes such as N-propargylamides.

Synthesis of homo polymers and block copolymers of chiral/achiral phenylacetylene derivatives. Spectroscopic and molecular modeling study on solvent‐dependent predominance of helical sense

AbstractA chiral acetylene monomer, (S)‐4‐(2‐butoxy)phenylacetylene [(S)‐1] and an achiral acetylene monomer, 4‐propoxyphenylacetylene (2) were block copolymerized using [(nbd)Rh{C(Ph)=CPh2}(PPh3)]/PPh3 as a catalyst to obtain chiral‐first/achiral‐second and achiral‐first/chiral‐second block copolymers, poly[(S)‐1]‐block‐poly(2) and poly(2)‐block‐poly[(S)‐1]. The block copolymers exhibited circular dichroism (CD) signals in THF attributable to helical conformation with predominantly one‐handed screw sense originating from the poly[(S)‐1] block. In CHCl3, the block copolymers exhibited CD signals with signs reversed from those in THF. The conformational stability of the copolymers was dependent on the composition of (S)‐1 units, regardless of the feed order of the chiral and achiral monomers. The solvent‐dependent predominance of helical sense was confirmed by the molecular dynamics (MD) simulations of poly[(S)‐1] 32‐mer models.

β-(Z)-Selective alkyne hydrosilylation by a N,O-functionalized NHC-based rhodium(I) catalyst.

Neutral and cationic cyclooctadiene rhodium(I) complexes with a lutidine-derived polydentate ligand having NHC and methoxy side-donor functions, [RhBr(cod)(κC-tBuImCH2PyCH2OMe)] and [Rh(cod)(κ2C,N-tBuImCH2PyCH2OMe)]PF6, have been prepared. Carbonylation of the cationic compound yields the dicarbonyl complex [Rh(CO)2(κ2C,N-tBuImCH2PyCH2OMe)]PF6 whereas carbonylation of the neutral compound affords a mixture of di- and monocarbonyl neutral complexes [RhBr(CO)2(κC-tBuImCH2PyCH2OMe)] and [RhBr(CO)(κ2C,N-tBuImCH2PyCH2OMe)]. These complexes efficiently catalyze the hydrosilylation of 1-hexyne with HSiMe2Ph with a marked selectivity towards the β-(Z)-vinylsilane product. Catalyst [RhBr(CO)(κ2C,N-tBuImCH2PyCH2OMe)] showed a superior catalytic performance, in terms of both activity and selectivity, and has been applied to the hydrosilylation of a range of 1-alkynes and phenylacetylene derivatives with diverse hydrosilanes, including HSiMe2Ph, HSiMePh2, HSiPh3 and HSiEt3, showing excellent β-(Z) selectivity for the hydrosilylation of linear aliphatic 1-alkynes. Hydrosilylation of internal alkynes, such as diphenylacetylene and 1-phenyl-1-propyne, selectively affords the syn-addition vinylsilane products. The β-(Z) selectivity of these catalysts contrasts with that of related rhodium(I) catalysts based on 2-picolyl-functionalised NHC ligands, which were reported to be β-(E) selective. An energy barrier ΔG‡ of 19.8 ± 2.0 kcal mol-1 (298 K) has been determined from kinetic studies on the hydrosilylation of 1-hexyne with HSiMe2Ph. DFT studies suggest that the methoxy-methyl group is unlikely to be involved in the activation of hydrosilane, and then hydrosilane activation is likely to proceed via a classical Si-H oxidative addition.

Synthesis of optically active star polymers consisting of helical poly(phenylacetylene) chains by the living polymerization of phenylacetylenes and their chiroptical properties.

Star polymers consisting of three helical poly(phenylacetylene) chains with a precisely controlled molecular weight (molar mass dispersity < 1.03) were successfully synthesized by the living polymerization of phenylacetylene derivatives with a Rh-based multicomponent catalyst system comprising trifunctional initiators, which have three phenylboronates centered on a benzene ring, the Rh complex [Rh(nbd)Cl]2, diphenylacetylene, triphenylphosphine, and a base. The analysis of chiroptical properties of the optically active star polymers obtained by the living polymerization of optically active phenylacetylene derivatives revealed that the star polymers exhibited chiral amplification properties owing to their unique topology compared with the corresponding linear polymers.

Expanding the scope of bis(catecholato)germane catalysis: hydrosilylation, hydroboration, Friedel-Crafts alkylation and oligomerization.

Various applications of bis(catecholato)germanes in catalysis were examined. The hydrosilylation of benzaldehydes, hydroboration of phenylacetylene derivatives, and Friedel-Crafts alkylation using arylalkenes and either diphenylamine or anisole was achieved. Furthermore, the recently reported oligomerization of α-methylstyrene catalyzed by bis(catecholato)germanes with weak donor ligands was examined further. The formation of a trimer species was observed in DCM. VTNA and Hammett analyses of the oligomerization reaction were conducted and an updated mechanism for bis(catecholato)germane catalysis is proposed.

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.

Synthesis of steroidal dihydropyrazole derivatives using green ZnO NPs and evaluation of their anticancer and antioxidant activity

Zinc oxide nanoparticles (ZnO NPs) were synthesized by a green method using Azadirachta indica leaf extract. The structure of the prepared ZnO (NPs) were characterized by FT-IR, XRD, SEM-EDX and TEM analyses. The biosynthesized ZnO (NPs) were then used as a catalyst for the synthesis of steroidal dihydropyrazole derivatives through a one-pot multicomponent reaction involving phenyl acetylene and hydrazine derivatives. The anticancer activity of newly synthesized compounds were evaluated against three cancer cell lines namely HeLa (human cervical carcinoma), Hep3B (human hepatocellular carcinoma) and MCF7 (human breast adenocarcinoma) by MTT assay. The tested compounds were found to be active against all cancer cell lines and less toxic towards normal peripheral blood mononuclear cells (PBMCs). Antioxidant activity have also been investigated via free radical scavenging ability using DPPH, FRAP and ABTS assay. The tested compounds were found to exhibit moderate to good antioxidant activity which increases with increase in the concentration of steroidal dihydropyrazoles. Among all the tested steroidal dihydropyrazoles, compound 17 is found to be most active.

Hydrotrifluoromethylation of Styrene and Phenylacetylene Derivatives under Visible-Light Photoredox Conditions

Photoredox processes have emerged recently as a powerful tool for methodology developments. In this context, the hydrotrifluoromethylation of alkenes and alkynes using visible light photoredox methodologies has proven its efficiency these last years. This micro-review summarizes the latest developments in this field.

Well‐Controlled Living Polymerization of Phenylacetylenes in Water: Synthesis of Water‐Soluble Stereoregular Telechelic Poly(phenylacetylene)s

AbstractWell‐controlled living polymerization of water‐soluble phenylacetylene derivatives in water was achieved for the first time using a multicomponent catalytic system consisting of [Rh(nbd)Cl]2, an aryl boronic acid, diphenylacetylene having carboxy groups, a tetraalkylammonium hydroxide, and a water‐soluble triphenylphosphine. This catalytic system enables a direct synthesis of various water‐soluble cis‐stereoregular poly(phenylacetylene)s having a narrow molecular weight distribution, the molecular weight of which can be controlled by the initial feed ratio of the monomer to the catalyst. Moreover, the syntheses of water‐soluble telechelic poly(phenylacetylene)s having various functional groups at both chain ends as well as a water‐soluble block copolymer were achieved.

Well-Controlled Living Polymerization of Phenylacetylenes in Water: Synthesis of Water-Soluble Stereoregular Telechelic Poly(phenylacetylene)s.

Well-controlled living polymerization of water-soluble phenylacetylene derivatives in water was achieved for the first time using a multicomponent catalytic system consisting of [Rh(nbd)Cl]2 , an aryl boronic acid, diphenylacetylene having carboxy groups, a tetraalkylammonium hydroxide, and a water-soluble triphenylphosphine. This catalytic system enables a direct synthesis of various water-soluble cis-stereoregular poly(phenylacetylene)s having a narrow molecular weight distribution, the molecular weight of which can be controlled by the initial feed ratio of the monomer to the catalyst. Moreover, the syntheses of water-soluble telechelic poly(phenylacetylene)s having various functional groups at both chain ends as well as a water-soluble block copolymer were achieved.

Intermolecular Carbosilylation of α-Olefins with C(sp3 )-C(sp) Bond Formation Involving Silylium-Ion Regeneration.

A regioselective addition of alkynylsilanes across unactivated, terminal alkenes is reported. The reaction is initiated by the capture of a sterically unhindered silylium ion by a silylated phenylacetylene derivative to form a bis(silylated) ketene‐like carbocation. This in situ‐generated key intermediate is the actual catalyst that maintains the catalytic cycle by a series of electrophilic addition reactions of silylium ions and β‐silicon‐stabilized carbocations. The computed reaction mechanism is fully consistent with the experimental findings. This unprecedented two‐component carbosilylation establishes a C(sp3)−C(sp) bond and a C(sp3)−Si bond in atom‐economic fashion.

Intermolekulare Carbosilylierung von α‐Olefinen mit C(sp3)−C(sp)‐Bindungsknüpfung unter Neubildung von Silyliumionen

AbstractEs wird über eine regioselektive Addition von Alkinylsilanen an nichtaktivierte, endständige Alkene berichtet. Die Reaktion wird durch Abfangen eines sterisch ungehinderten Silyliumions von einem silylierten Phenylacetylenderivat unter Bildung eines bissilylierten ketenartigen Carbokations eingeleitet. Diese lokal erzeugte Schlüsselzwischenstufe ist der tatsächliche Katalysator, der den Katalysecyclus über eine Abfolge von elektrophilen Additionsreaktionen von Silyliumionen und durch den β‐Siliciumeffekt stabilisierten Carbokationen aufrechterhält. Der berechnete Reaktionsmechanismus steht in vollständigem Einklang mit den experimentellen Befunden. Mit dieser vormals unbekannten Zweikomponentencarbosilylierung werden eine C(sp3)−C(sp)‐ und eine C(sp3)−Si‐Bindung atomökonomisch aufgebaut.

Cobalt‐Catalyzed Hydroalkynylation of Vinylaziridines

AbstractTransition metal‐catalyzed hydroalkynylation reactions are efficient transformations allowing the straightforward formation of functionalized alkynes. Therein, we disclose the cobalt‐catalyzed hydroalkynylation of vinylaziridines giving rise to both linear and branched enynes. The optimization of the reaction conditions allowed to determine the key parameters of the cobalt‐based catalytic system. The scope investigation showed that the cobalt‐catalyzed hydroalkynylation is mainly limited to phenylacetylene derivatives. In most cases branched and linear enynes were isolated in equimolar proportions (20 examples). Additional experiments allowed us to propose a plausible mechanism. Finally, the hydroalkynylation products were further subjected to an iodocyclization affording a 2,3‐dihydropyrrole derivative and a platinum‐catalyzed cycloisomerization.magnified image

Sulfur crosslinked poly(m-aminothiophenol)/potato starch on mesoporous silica for efficient Hg(II) removal and reutilization of waste adsorbent as a catalyst

Elemental sulfur, as a by-product of petroleum refining, is regarded as a solid waste stored in above-ground deposits due to limited existing applications, meanwhile, mercury contamination is one of the current environmental issues considering its high toxicity to the human, and how to safely dispose of hazardous waste adsorbents is still an unavoidable problem. This study addresses these need by utilizing sulfur for preparation of a polysulfide complex material to capture Hg(II) and convert the Hg(II)-containing spent adsorbent into a catalyst. Initially, the mesoporous silica was prepared and functionalized by using diatomite and APTES, then, an in-situ preparation method was applied to obtain the amine-mesoporous silica/poly(m-aminothiophenol) nanocomposite (MAP), subsequently sulfur was copolymerized with MAP and vinylic-potato starch through inverse vulcanization, forming the sulfur crosslinked polymers composite cp(MAP-S-PS). Many characterizations were employed to determine the physicochemical structure and morphology of cp(MAP-S-PS). The adsorption study showed the cp(MAP-S-PS) exhibited the theoretical maximum adsorption capacity of 436.68 mg/g, good regeneration performance after 5 cycles and excellent selectivity between Hg(II) ions and common cations. Furthermore, the collected spent adsorbent cp(MAP-S-PS)/Hg(II) was reused as a catalyst for synthesis of acetophenone with 89% yield, and most of phenylacetylene derivatives were also transformed to corresponding acetophenone in good yields.

Synthesis of five propargylamines derivative via the multicomponent reaction catalyzed by a deep eutectic solvent

Deep eutectic solvents (DES), a new generation ionic liquids, are green reactive media in organic synthesis, electrochemical, and biomass conversion. In this paper, we have developed a deep eutectic solvent [ethylene glycol]4[ZnCl2], simply prepared from choline chloride with ethylene glycol and used as a catalyst for the three-component reaction to synthesize propargylamine from available substrates including piperidine, phenylacetylene and benzaldehyde derivatives. The reaction mixture was activated by magnetic stirring and the optimization of conditions was investigated including temperature, time, catalytic mass, substrate effect and recycled catalyst. At 80 ◦ C, we successfully synthesized 5 propargylamine derivatives over a period of 180 minutes with high efficiency and only used 2% moles of catalyst. Desired products are structurally identified by NMR and MS (nuclear magnetic resonance 1H, 13C NMR and gas chromatography coupled mass spectrometry GC-MS). The results showed that DES [ethylene glycol]4[ZnCl2] catalyzed the efficiency of this reaction and the ability to reuse many times with negligible reduction in activity. Research to expand the scope of the substrate (heterocyclic oxygen and nitrogen compounds) and reaction mechanism are underway in the laboratory. Simple, efficient reaction processes have been the potential for industrial applications.

New network polymer functionalized magnetic-mesoporous nanoparticle for rapid adsorption of Hg(II) and sequential efficient reutilization as a catalyst

Herein, a novel magnetic network polymer composite (MCTP) was constructed by introducing the poly(m-aminothiophenol) and chitosan onto the magnetic-mesoporous nanoparticle under tannic acid as a crosslinking agent. Adsorption study indicated the removal rate and adsorption capacity of MCTP reached 98.16% and 245.49 mg/g within 15 min, meanwhile, it showed favorable recyclability after 5 cycles and excellent selectivity. The high-efficiency adsorption of Hg(II) is mainly dominated by chemical adsorption through forming stronger coordination bonds or Hg(II)-chelate complex between sulfur or nitrogen groups and Hg(II). Furthermore, the reutilization of toxic spent adsorbent was explored by converting MCTP/Hg(II) into a catalyst for synthesis of acetophenone with 99% yield, and most of phenylacetylene derivatives were transformed to corresponding acetophenone in excellent yields (>98%). Overall, this work not only reports a promising magnetic composite for treatment of Hg(II)-containing wastewater, but establishes the value-added utilization of waste adsorbent.

Multiwalled carbon nanotubes crowned with nickel‐ferrite magnetic nanoparticles assisted heterogeneous catalytic strategy for the synthesis of benzo[d]imidazo[2,1‐b]thiazole scaffolds

AbstractPresent manuscript elicits an account of the sonication promoted multicomponent reactions strategy assisted by multiwalled carbon nanotubes embraced with nickel‐ferrite (NiFe2O4‐CNTs) magnetic nanoparticles, as a heterogeneous catalyst to synthesize a novel series of pharmacologically active benzo[d]imidazo[2,1‐b]thiazole scaffolds. The synthesis of these biologically active derivatives was achieved via. A3 coupling involving 2‐aminobenzothiazole, pertinent aryl aldehydes and phenyl acetylene derivatives, proceeded in PEG 400 as green solvent under aerobic conditions to afford the products in good to excellent yields. The higher environmental compatibility and sustainability factors such as higher ecoscale score, smaller E‐factor and appreciable atom economy put this etiquette under the parasol of green chemistry precepts. The characterization of synthesized catalysts was attained through varied techniques viz. powder X‐ray diffraction, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, Raman, FT‐IR, VSM and TGA‐DTA‐DTG analyses, dispersion studies, and nitrogen porosimetry analyses. The structures of the synthesized compounds were also endorsed by extensive spectroscopic studies (FT‐IR, 1H and 13C NMR, Mass) and elemental analyses.

Synthesis of poly(phenylacetylene)s containing chiral phenylethyl carbamate residues as coated-type CSPs with high solvent tolerability.

Two novel helical poly(phenylacetylene) derivatives containing chiral phenylethyl carbamate residues in the end of each side chain (PPA-S and PPA-R) were synthesized by polymerization of the corresponding phenylacetylene monomers using Rh(nbd)BPh4 as a catalyst in DMF. The enantioseparation properties of the polymers were evaluated as coated-type chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC). Under the same chromatographic conditions, PPA-S and PPA-R showed different enantioseparation properties, indicating that the different interactions between the analytes and the polymers, which result from the different chiral phenylethyl carbamate groups in the end of each side chains. Racemates 1, 7, and 8 could be better resolved on PPA-S, while racemate 6 was separated on PPA-R more efficiently. In addition, the coated-type CSPs showed good solvent tolerability and could work without any damage by introducing the polar solvents, such as CHCl3 and THF, in eluent. Moreover, some racemates could be better resolved on these coated-type CSPs with the addition of THF to the eluent.

Copper quinolate: A simple and efficient catalytic complex for coupling reactions

We describe an effective and novel method to prepare N‐aryl imidazoles via the copper quinolate‐catalyzed N‐arylation of aryl halides and imidazoles. A wide range of products were obtained in moderate to excellent yields under the optimal reaction conditions. Applying standard conditions, the model reaction could be performed on a gram scale. This method also presents a new avenue to the “click” reaction of terminal alkynes, benzyl bromide, and sodium azide and to the construction of C–C bonds by homocoupling of phenylboronic acid or phenylacetylene derivatives with the aid of copper quinolate.