Aryl Alkynes Research Articles

A copper-catalyzed three component reaction of aryl acetylene, sulfonyl azide and enaminone to form iminolactone via 6π electrocyclization.

We developed a copper-catalyzed three component reaction of aryl acetylene, enaminone and sulfonyl azide to construct iminolactone via a cascade process involving copper-catalyzed alkyne-azide cycloaddition (CuAAC), Michael addition of metalated ketenimine followed by elimination and 6π electrocyclization.

A single palladium site catalyst as a bridge for converting homogeneous to heterogeneous in dimerization of terminal aryl acetylenes

Herein, we utilize the surface dangling bond of MOFs as anchoring sites to access single Pd sites embedded on a hollow MOF nanobox.

Metal-free synthesis of quinolines by direct condensation of amides with alkynes: revelation of N-aryl nitrilium intermediates by 2D NMR techniques

Employing triflic anhydride/2-fluoropyridine as an activation system, the coupling reactions of secondary N-aryl amides with terminal alkynes yielded substituted quinolines in moderate to excellent yields. The reaction tolerated both electron-donating and electron-withdrawing groups at the benzamide moiety. Electron-rich aryl acetylenes served as excellent coupling partners, and aliphatic terminal alkynes such as cyclopropyl and conjugate vinyl acetylenes could also be used as reaction partners. By means of 2D NMR techniques (heteronuclear multiple bond correlation (HMBC), heteronuclear single quantum correlation (HSQC)), nitrilium ions were probed as reactive intermediates which are in contrast with that suggested by Movassaghi on the basis of in situ IR monitoring experiments. On the basis of these results, a plausible mechanism for the formation of quinolines was suggested.

Regioselective Synthesis of 2‐(Trifluoromethyl)‐3‐ethoxycarbonyl‐4‐(2‐oxo‐2‐arylethyl)‐4H‐chromene Derivatives by [3, 3] Sigmatropic Rearrangement

AbstractA new and an efficient method has been developed to synthesize ethyl 4‐(2‐oxo‐2‐arylethyl)‐2‐(trifluoromethyl)‐4H‐chromene‐3‐carboxylate derivatives 3 from 2H‐chromene 1 and aryl acetylene 2 through [3, 3] sigmatropic rearrangement in presence of catalytic amount of BF3.OEt2 (10 mol %).

Base-Mediated Three-Component Tandem Reactions for the Synthesis of Multisubstituted Pyrimidines.

A base-mediated three-component tandem reaction for the synthesis of multisubstituted pyrimidines from amidines, aryl alkynes, and aldehydes in a one-pot manner has been developed. Advantages of this transformation include being transition-metal-free, high efficiency, available starting materials, and being environmentally friendly.

Chemical Fixation of CO2 and Other Heterogeneous Catalytic Studies by Employing a Layered Cu-Porphyrin Prepared Through Single-Crystal to Single-Crystal Exchange of a Zn Analogue.

A solvothermal reaction of Zn(NO3 )2 ⋅6 H2 O, tetra-(4-pyridyl)porphyrin (H2 TPyP), and 4,4'-oxybis(benzoic acid) (H2 OBA) resulted in a new two-dimensional Zn- porphyrin metal-organic framework compound, [Zn2 (C40 H24 N8 )0.5 (C14 H8 O5 )(DMA)](DMA)(H2 O)6 (1; DMA=N,N-dimethylacetamide). The ZnII ions present in 1 could be exchanged by using a solution of Cu(NO3 )2 ⋅3 H2 O in DMA at room temperature to give [Cu2 (C40 H24 N8 )0.5 (C14 H8 O5 )(DMA)](DMA)(H2 O)3 (Cu∈1). The extra-framework solvent molecules have been shown to be reversibly removed or exchanged without collapse of the framework. Solvent-free Cu∈1 was explored as an active heterogeneous catalyst towards three different organic reactions: 1) the chemical fixation of CO2 into cyclic carbonate at room temperature and 1 atm; 2) the nitroaldol reaction under solvent-free conditions, and 3) the three-component coupling of aminopyridine, benzaldehyde, and aryl alkynes followed by 5-exo-dig cyclization to produce the important pharmacophore imidazopyridine.

Kinetics and Mechanistic Insights into the Acetate-Assisted Dimerization of Terminal Alkynes under Ruthenium- and Acid-Promoted (RAP) Catalysis

The mechanism of the dimerization of terminal aryl alkynes promoted by [{RuCl(μ-Cl)(η6-p-cymene)}2](1)/AcOH, under cooperative transition metal/Bronsted acid catalysis, has been investigated with regard to (i) the activation of the dinuclear ruthenium complex and (ii) the catalytic formation of the trans-1,4-diaryl-1,3-enyne products, by a detailed kinetic investigation of both processes. Complex 1 is subject to a slow solvolytic process in neat acetic acid or is transformed rapidly in the presence of sodium acetate to form the monomeric ruthenium(II) acetato complex [RuCl(η6-p-cymene)(OAc)]. The latter is the active catalytic species promoting the alkyne dimerization process, via initial π-alkyne coordination and intramolecular C–H abstraction by the acetate ligand, as key steps of the catalytic cycle. The presence of additive acetate salts allows for the reaction to proceed at room temperature with short reaction times and high trans/cis stereoselectivity, thus rendering this catalytic system among the ...

The Reactions of Aryl Tin(II) Hydrides {AriPr6Sn(μ-H)}2 (AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) and {AriPr4Sn(μ-H)}2 (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) with Aryl Alkynes: Substituent Dependent Structural Isomers

The reactions of the aryl tin(II) hydrides {AriPr6Sn(μ-H)}2 (AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) and {AriPr4Sn(μ-H)}2 (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) with aryl alkynes were investigated. Reaction of {AriPr6Sn(μ-H)}2 and {AriPr4Sn(μ-H)}2 with 2 equiv of diphenyl acetylene, PhCCPh, afforded the aryl alkenyl stannylenes AriPr6SnC(Ph)C(H)Ph (1) and AriPr4SnC(Ph)C(H)Ph (2). In contrast, the analogous reactions of {AriPr6Sn(μ-H)}2 with 2 equiv of phenyl acetylene, HCCPh, afforded a high yield of the cis-1,2 addition product AriPr6(H)SnC(H)C(Ph)Sn(H)AriPr6 (3), which has a four-membered Sn2C2 core structure comprised of two Sn–Sn bonded Sn(H)AriPr6 units bridged by a −C(H)═C(Ph)– moiety. The corresponding reaction of the less bulky hydride {AriPr4Sn(μ-H)}2 with 2 equiv of phenyl acetylene leads to AriPr4SnC(H)C(Ph)Sn(H)2AriPr4 (4) which unlike 3 has no Sn–Sn bonding. Instead, the tin atoms are connected solely by a −C(H)═C(Ph)– moiety. Each tin atom carries a AriPr4 substituent but one is also substituted...

Lewis Acid-Catalyzed Selective [2 + 2]-Cycloaddition and Dearomatizing Cascade Reaction of Aryl Alkynes with Acrylates.

Combined Lewis acid, consisting of two or more Lewis acids, sometimes shows unique catalytic ability, and it may promote reactions which could not be catalyzed by any of the Lewis acids solely. On the other hand, the development of efficient methods for the facile synthesis of cyclobutenes and densely functionalized decalins is an attractive target for synthetic chemists due to their versatile synthetic utilities and widespread occurrence in natural products. Herein, we wish to report an efficient method for the assembly of cyclobutenes and densely functionalized decalin skeletons through In(tfacac)3-TMSBr catalyzed selective [2 + 2]-cycloaddition and dearomatizing cascade reaction of aryl alkynes with acrylates with high chemo- and stereoselectivity. The obtained cyclobutene could be easily converted into cyclobutane as well as synthetically useful 1,4- and 1,5-diketones with high chemo- and stereoselectivity. On the basis of mechanistic studies, plausible reaction mechanisms were proposed for both the [2 + 2]-cycloaddition and the dearomatizing cascade reaction. Finally, the computational studies of reaction mechanisms were conducted, and the results suggest that the combined Lewis acid could efficiently promote both reactions.

Copper‐Catalyzed Decarboxylative Alkylation of Terminal Alkynes

AbstractA copper‐catalyzed decarboxylative alkylation of terminal alkynes under mild reaction conditions has been reported. Various alkyl diacyl peroxides were applied as the alkyl source for the formation of C(sp3)−C(sp) bond. A range of terminal alkynes including aryl alkynes and alkyl alkynes delivered the alkylated internal alkynes with good to high performances. Mechanism studies suggested that this reaction involves a free radical pathway.magnified image

Aqueous-Phase Synthesis of Size-Tunable Copper Nanocubes for Efficient Aryl Alkyne Hydroboration.

Copper nanocubes with average sizes of 82, 95, and 108 nm have been synthesized in an aqueous mixture of cetyltrimethylammonium chloride (CTAC) surfactant, copper acetate, and sodium ascorbate reductant heated at 100 °C for 40 min. Copper nanowires with an average length of 25 μm can also be prepared this way by simply increasing the volume of sodium ascorbate introduced. Small shifts in the plasmonic absorption band positions with tunable particle sizes have been observed. The copper nanocubes were employed to catalyze hydroboration of phenylacetylene and various substituted aryl alkynes with 100 % (E)-product selectivity and 82-95 % product yields. The copper nanocubes are cheap to make and should catalyze a broad scope of organic coupling reactions.

Synthesis of Enaminones by a Palladium-Catalyzed Four-Component Carbonylative Addition Reaction

A palladium-catalyzed carbonylative addition reaction of aryl bromides, amines, and alkynes has been developed. The reaction ­occurs readily in N,N-dimethylformamide with PdCl2(PPh3)2 as a catalyst to give the corresponding enaminones in medium to excellent yields. Furthermore, a mechanism for the palladium-catalyzed four-component carbonylative addition reaction is proposed.

A Convergent Synthesis of Functionalized Alkenyl Halides through Cobalt(III)‐Catalyzed Three‐Component C−H Bond Addition

AbstractA CoIII‐catalyzed three‐component coupling of C(sp2)−H bonds, alkynes, and halogenating agents to give alkenyl halides is reported. This transformation proceeds with high regio‐ and diastereoselectivity, and is effective for a broad range of aryl and alkyl terminal alkynes. Diverse C−H bond partners also exhibit good reactivity for a range of heteroaryl and aryl systems as well as synthetically useful secondary and tertiary amide, urea, and pyrazole directing groups. This multicomponent transformation is also compatible with allenes in place of alkynes to furnish tetrasubstituted alkenyl halides, showcasing the first halo‐arylation of allenes.

A Convergent Synthesis of Functionalized Alkenyl Halides through Cobalt(III)-Catalyzed Three-Component C-H Bond Addition.

A CoIII -catalyzed three-component coupling of C(sp2 )-H bonds, alkynes, and halogenating agents to give alkenyl halides is reported. This transformation proceeds with high regio- and diastereoselectivity, and is effective for a broad range of aryl and alkyl terminal alkynes. Diverse C-H bond partners also exhibit good reactivity for a range of heteroaryl and aryl systems as well as synthetically useful secondary and tertiary amide, urea, and pyrazole directing groups. This multicomponent transformation is also compatible with allenes in place of alkynes to furnish tetrasubstituted alkenyl halides, showcasing the first halo-arylation of allenes.

Nanoparticles Covered Surfaces for Post-functionalization with Aromatic Groups to Obtain Parahydrophobic Surface with High Water Adhesion (Petal Effect)

Numerous exceptional properties can be observed in nature. Among these properties, parahydrophobic feature is of interest. This property describes material with high adhesion with water such as rose petals or gecko foot. Such kind of surface presents a real potential for applications in the field of water harvesting systems. In this work, we report a new synthetic strategy to mimic this property. Here, we combine three strategies in one. First, a monomer is electropolymerized in order to form the starting structured surface. Then, nanoparticles are grafted on the surface to increase the structuration and consequently to create the reactive surface. Finally, the grafted surface is post-functionalized (Huisgen reaction) with various aryl alkynes to control the surface chemistry and energy. This strategy allows to reach surfaces with both very high hydrophobic properties (θ = 140°) and high water adhesion. This work also includes the surface wettability, roughness and morphology investigation in order to study the impact of the starting monomer structure and post-functionalization on the surface properties.

A nickel(II) thiosemicarbazonato complex: synthesis, structure, electrochemistry, and application in catalytic coupling of terminal alkynes with arylboronic acids

A simple route for the synthesis of a new square-planar nickel(II) complex of 2-((3-methylthiophen-2-yl)methylene)hydrazinecarbothioamide is described. Elemental analysis, solution conductivity, and spectral measurements were used to authenticate the composition of the complex. In addition, the X-ray crystal structure of the complex was obtained. Each of the two ligands of the centrosymmetric structure is coordinated to the metal center via the azomethine N and the thioimidate S atoms, forming five-membered chelate rings. Infrared and NMR spectroscopic features of the complex are consistent with its molecular structure. The complex displays a quasi-reversible reduction with E 1/2 of −0.83 V (ΔE p 160 mV), indicating that the ligand system can stabilize the Ni(I) oxidation state. The complex acts as an active catalyst for the C–C coupling of aryl acetylenes with arylboronic acids containing a variety of substituents. The influence of solvent, base, reaction temperature, and catalyst loading on the C–C coupling reaction was evaluated. A new square-planar nickel(II) complex bearing 2-((3-methylthiophen-2-yl)methylene)-hydrazinecarbothioamide was synthesized and characterized by elemental analysis, FTIR, NMR, and single-crystal X-ray crystallographic technique. Cyclic voltammetric study indicates stabilization of Ni(I) oxidation state. The complex acts as an effective catalyst for the carbon–carbon cross-coupling reaction of substituted phenylacetylenes with various arylboronic acids under optimized conditions.

Combining ethylenediamine and ionic liquid functionalities within SBA-15: A promising catalytic pair for tandem Cu–AAC reaction

This paper discloses the assembly and characterization of an advanced heterogeneous catalyst formulated as CuI@SBA-15/PrEn/ImPF6. It is based on a mesoporous silica SBA-15 skeleton which bears a supported ethylenediamine/CuI complex and covalently anchored imidazolium/PF6 ionic liquid. This catalyst was successfully applied in tandem methods for triazole synthesis starting from different substrate pairs: aryl halides and aryl acetylenes (method A), arylboronic acids and aryl acetylenes (method B). The CuI@SBA-15/PrEn/ImPF6 catalyst showed high activity (up to 90% yields of triazole products under optimized reaction conditions), high stability and no appreciable leaching of CuI owing to its strong binding via the coordination with PrEn functionality. Therefore, the catalyst can be recycled for several consecutive runs (7–14 cycles) in this new synthetic method. For both methods A and B, specific types of green approaches were developed and the favorable products were produced in high yields.

Cesium Hydroxide-mediated Regio- and Stereoselective Hydroamidation of Internal Aryl Alkynes with Primary Amides

A cesium hydroxide-mediated hydroamidation of internal aryl alkynes with primary amides has been developed. The reaction proceeds with high anti-selectivity to deliver the corresponding stereodefined (Z)-enamides in good yields. The alkali base-promoted system is also compatible with unsymmetrical aryl alkyl alkynes, and the hydroamidated products are obtained with high regioselectivity as well as stereoselectivity.

Exploring the Influence of Phosphine Ligation on the Gold-Catalyzed Hydrohydrazination of Terminal Alkynes at Room Temperature

The synthesis and/or NMR/X-ray characterization of a new series of (L)AuCl complexes is reported, featuring BippyPhos, AdJohnPhos, silyl ether based ligands including OTips-DalPhos, and PAd-DalPhos. These complexes, along with previously reported analogues featuring cataCXium-A, tBuJohnPhos, and Mor-DalPhos, were screened as precatalysts using LiB(C6F5)4·2.5Et2O as an activator in the hydrohydrazination of terminal aryl alkynes with hydrazine hydrate under unprecedentedly mild conditions (25 °C, 1 mol % Au). The precatalyst (cataCXium-A)AuCl proved to be particularly effective in such transformations, demonstrating useful scope.

Bipyridine Facilitates Regioselective Dimerization of Alkynes in the Absence of Transition Metal

AbstractWe herein present a transition metal free protocol for the dimerization of terminal aryl alkynes to prepare enyne derivatives using potassium tert‐butoxide in the presence of catalytic amount of 2,2′‐bipyridine. The reaction is compatible with a wide range of substrates resulting in high to moderate yields of the corresponding head‐to‐head dimers with E‐selectivity.