Coupling Reaction Of Terminal Alkynes Research Articles

A Novel Copper-Catalyzed Synthesis of N-Monosubstituted 2-Alkynimidamides from 1-Alkynes and Trichloroacetamidines

A one-pot Cu-catalyzed synthesis of functionalized alkynyl imidamide by terminal alkynes, trichloroacetonitrile and aniline or benzyl amine is reported. The compounds were produced via coupling reaction of terminal alkynes with trichloroacetamidine. This method was performed under mild, ligand-free conditions and easy work-up method.

Chemoselective On-surface Homocoupling of Terminal Alkynes Catalyzed by Exogenous Cupric Ions.

The on-surface coupling reactions of terminal alkynes catalyzed by exogenous cupric ions on chemically inert highly oriented pyrolytic graphite (HOPG) surface have been investigated by scanning tunnelling microscopy. In the presence of exogenous cupric ions, diyne-linked nanostructures generated via homocoupling of terminal alkynes are the exclusive products, whereas no coupling reaction occurs for the terminal alkynes on the surface in the absence of the cupric ions, suggesting that exogenous cupric ions are efficient to catalyze the highly chemoselective on-surface reaction of terminal alkynes. The HOPG surface displays a template effect to the growth and alignment of the products on the surface. As a result, 2D arrays of diyne-linked zigzag polymers and 2D diyne-linked porous polymers are fabricated from ditopic monomer 3,6-diethynylcarbazole and tritopic monomer 1,3,5-tris-(4-ethynylphenyl) benzene, respectively. This synthetic strategy combining the high selectivity of cupric ion catalyst as well as the template effect of on-surface synthesis approach could be a general strategy to fabricate diyne-linked nanostructures and nanomaterials on solid surfaces.

Harnessing the Untapped Catalytic Potential of a CoFe2O4/Mn-BDC Hybrid MOF Composite for Obtaining a Multitude of 1,4-Disubstituted 1,2,3-Triazole Scaffolds.

Metal-organic frameworks derived nanostructures with extraordinary variability, and many unprecedented properties have recently emerged as promising catalytic materials to address the challenges in the field of modern organic synthesis. In this contribution, the present work reports the fabrication of an intricately designed magnetic MOF composite based on Mn-BDC (manganese benzene-1,4-dicarboxylate/manganese terephthalate) microflakes via a facile and benign in situ solvothermal approach. Structural information about the as-synthesized hybrid composite has been obtained with characterization techniques such as TEM, SEM, XRD, FT-IR, AAS, EDX, ED-XRF, and VSM analysis. Upon investigation of catalytic performance, the resulting material unveils remarkable efficacy toward facile access of a diverse array of pharmaceutically active 1,2,3-triazoles from a multicomponent coupling reaction of terminal alkynes, sodium azide, and alkyl or aryl halides as coupling partners. In addition to a wide substrate scope, the catalyst with highly accessible active sites also possesses a stable catalytic metal center along with superb magnetic properties that facilitate rapid and efficient separation. The prominent feature that makes this protocol highly desirable is the ambient and greener reaction conditions in comparison to literature precedents reported to date. Further, a plausible mechanistic pathway is also proposed to rationalize the impressive potential of the developed catalytic system in the concerned reaction. We envision that findings from our study would not only provide new insights into the judicious design of advanced MOF based architectures but also pave the way toward greening of industrial manufacturing processes to tackle critical environmental and economic issues.

Palladium-catalyzed double coupling reaction of terminal alkynes with isocyanides: a direct approach to symmetrical N-aryl dialkynylimines

A novel and efficient one-pot synthesis of symmetrical N-aryl dialkynylimines via palladium-catalyzed and copper-promoted isocyanide insertion, cross-coupling and elimination has been developed. This method features readily available starting materials, mild reaction conditions and high atom efficiency as well as simple one-pot operation, which make this strategy highly attractive. Moreover, 2-iodobenzo[f]quinoline derivatives can be obtained via electrophilic cyclization of N-aryl dialkynylimines.

DFT study on theE-stereoselective reductive A3-coupling reaction of terminal alkynes with aldehydes and 3-pyrroline

The mechanism of the Cu(i)-catalyzed reductive A3-coupling reaction of terminal alkynes with aldehydes and 3-pyrroline for the synthesis ofE-allylic amines has been studied by DFT calculations.

Copper Nanoparticle Catalyzed Reductive Coupling Reactions of Terminal Alkynes

Copper Nanoparticle Catalyzed Reductive Coupling Reactions of Terminal Alkynes

Catalytic Alkynylation of Polyfluoroarenes by Amide Base Generated In Situ.

We herein demonstrate that the amide base generated in situ from CsF and N(TMS)3 catalyzes the deprotonative coupling reactions of terminal alkynes with polyfluoroarenes, wherein mono- and dialkynylations occur efficiently for penta- and hexafluorobenzenes, respectively. Tetraalkynylated products could also be synthesized from dialkynylated compounds.

Synthesis of ynones at room temperature catalyzed by copper chloride cryptand complex under solvent free conditions

An air-stable highly efficient reusable CuCl2-cryptand-[2.2.Benzo] catalyst is reported first time for coupling reaction of terminal alkynes with different acyl chlorides in the presence of triethylamine acting both as base and solvent at room temperature to give the corresponding ynones. Easy-going, short reaction time, cost-effective, palladium-, phosphorus- and solvent-free, high yield and recyclability up to 5th times make this method green procedure for ynones’ synthesis with wide substrate variety.

Caffeine gold complex supported on magnetic nanoparticles as a green and high turnover frequency catalyst for room temperature A3 coupling reaction in water

A new heterogeneous catalyst derived from gold (III) and supported on caffeine‐coated magnetic nanoparticles, Fe3O4@Caff‐Au, has been prepared and characterized using different techniques. This magnetic gold composite shows high catalytic activity in A3 coupling reactions of terminal alkynes, aldehydes and secondary amines. Using this green catalyst, propargylamines are obtained in high turnover frequency in short reaction times using water as solvent at room temperature. This stable and ready accessible catalyst can be easily recycled magnetically for at least nine consecutive runs without significant loss of activity and with slight aggregation of Au species.

A convenient route to 1,3-diynes using ligand-free Cadiot-Chodkiewicz coupling reaction at room temperature under aerobic conditions

In this study, we report a copper-catalyzed ligand-free Cadiot-Chodkiewicz coupling reaction. No additives or ligands are required for this Cu-catalyzed C(sp)-C(sp) coupling reaction of terminal alkynes with alkynyl halides. The low cost of copper catalyst, excellent yield of the products, suppression of side-products and mild reaction conditions are the major advantages of this protocol.

Gold-Catalyzed Oxidative Coupling of Terminal Alkynes and Borane Adducts: Efficient Synthesis of α-Boryl Ketones

Herein, we report a gold-catalyzed oxidative coupling reaction of terminal alkynes and borane adducts for the synthesis of α-boryl carbonyl compounds, which are versatile organoboron reagents and could undergo various synthetic transformations. This efficient, regiospecific reaction showed good functional group tolerance and could be used for late-stage modification of structurally complex bioactive compounds.

Palladium-Catalyzed Reductive Coupling Reaction of Terminal Alkynes with Aryl Iodides Utilizing Hafnocene Difluoride as a Hafnium Hydride Precursor Leading to trans-Alkenes.

Herein, we describe a reductive cross-coupling of alkynes and aryl iodides by using a novel catalytic system composed of a catalytic amount of palladium dichloride and a promoter precursor, hafnocene difluoride (Cp2 HfF2 , Cp=cyclopentadienyl anion), in the presence of a mild reducing reagent, a hydrosilane, leading to a one-pot preparation of trans-alkenes. In this process, a series of coupling reactions efficiently proceeds through the following three steps: (i) an initial formation of hafnocene hydride from hafnocene difluoride and the hydrosilane, (ii) a subsequent hydrohafnation toward alkynes, and (iii) a final transmetalation of the alkenyl hafnium species to a palladium complex. This reductive coupling could be chemoselectively applied to the preparation of trans-alkenes with various functional groups, such as an alkyl group, a halogen, an ester, a nitro group, a heterocycle, a boronic ester, and an internal alkyne.

Copper-Catalyzed C(sp)-C(sp3) Coupling of Terminal Alkynes with Alkylsilyl Peroxides via a Radical Mechanism.

A copper-catalyzed C(sp)-C(sp3) coupling reaction between terminal alkynes and alkylsilyl peroxides is reported. In the presence of a copper catalyst and 4-dimethylaminopyridine, the reaction smoothly affords a variety of internal alkynes by coupling alkylsilyl peroxides and terminal alkynes. Mechanistic studies suggest that the reaction proceeds via a radical mechanism, whereby the alkyl radicals are generated from the alkylsilyl peroxides. The present transformation represents a rare example of a radical-mediated C(sp)-C(sp3) coupling reaction of terminal alkynes.

Carbon Nitride‐Supported Silver Nanoparticles: Microwave‐ Assisted Synthesis of Propargylamine and Oxidative C‐C Coupling Reaction

AbstractIn the present study we have, synthesized silver nanoparticles supported on carbon nitride AgNPs@g‐C3N4 and investigated its catalytic aspects by using microwave. We found that silver nanoparticles supported on g‐C3N4 were highly active in the A3‐coupling reaction of (Aldehyde, secondary amine and terminal alkynes) for the synthesis of propargylamines with excellent yield up to 97% and in C−C coupling reaction of terminal alkynes for the synthesis of 1, 3‐diyne with excellent yield up to 98%. We have achieved excellent TON (72932), TOF (3636 min−1), E‐factor (0.27) and atom economy AE (94%). Reaction parameters like effect of catalyst quantity, effect of time and effect of temperature was deeply studied. The catalyst was characterized by SEM, HR‐TEM, EDX, XRD, ICP‐AES and IR.

Palladium‐Catalyzed Dehydrogenative Coupling Reaction of Terminal Alkynes with Unactivated Alkenes

Terminal alkynes having a bulky substituent dehydrogenatively couple with unactivated terminal alkenes with catalysis of palladium. The terminal sp carbon forms a bond with the internal sp2 carbon of the alkene regioselectively to produce branched, conjugated 1,3‐enynes with wide functional group tolerance.

ChemInform Abstract: Nickel‐Catalyzed Stereoselective Dicarbofunctionalization of Alkynes.

AbstractA radical‐mediated, three‐component coupling reaction of terminal alkynes, areneboronic acids, and alkyl halides leads to trisubstituted alkenes with high regio‐ and stereoselectivity.

Asymmetric Three-Component Coupling Reaction of Alkyne, Enone, and Aldehyde Catalyzed by Chiral Phebox Ruthenium Catalysts.

Catalytic asymmetric three-component coupling reactions of terminal alkynes, α,β-unsaturated ketones, and aldehydes were studied. The chiral ruthenium complexes containing bis(oxazolinyl)phenyl ligands were found to serve as efficient catalysts for a tandem reaction based on conjugate addition of terminal alkynes to α,β-unsaturated ketones and subsequent aldol reaction with aldehydes, giving β-hydroxyketone derivatives containing α-propargyl groups in high yields with moderate to good enantioselectivities. This method can produce various functional molecules from commercially available substrates in a one-pot procedure. The absolute configuration of the major product was determined by X-ray analysis. The control experiments suggested that a ruthenium enolate species generated in situ by conjugate addition could be involved as an intermediate for the aldol coupling with an aldehyde.

Synergistic Rhodium/Copper Catalysis: Synthesis of 1,3-Enynes and N-Aryl Enaminones.

Synergistic rhodium/copper catalysis enables new three-component coupling reactions of terminal alkynes and α-diazoketones and/or arylamines, allowing dediazotized carbene C-H insertion for the synthesis of functionalized 1,3-enynes and N-aryl enaminones with high stereoselectivity. The synthetic utility of these transformations results in subsequent C-C or/and C-N bond-forming reactions to effectively build up functional molecules with potential significance.

Identifying a Highly Active Copper Catalyst for KA(2) Reaction of Aromatic Ketones.

The well-established A(3) coupling reaction of terminal alkynes, aldehydes, and amines provides the most straightforward approach to propargylic amines. However, the related reaction of ketones, especially aromatic ketones, is still a significant challenge. A highly efficient catalytic protocol has been developed for the coupling of aromatic ketones with amines and terminal alkynes, in which Cu(I) , generated in situ from the reduction of CuBr2 with sodium ascorbate, has been identified as the highly efficient catalyst. Since propargylic amines are versatile synthetic intermediates and important units in pharmaceutical products, such an advance will greatly stimulate research interest involving the previously unavailable propargylic amines.

An efficient alkynylation of 4-thiazolidinone with terminal alkyne under C–H functionalisation

A method of palladium catalysed efficient alkynylation through the cross coupling reaction of terminal alkynes with the slightly more acidic C–H bonds of 4-thiazolidinone has been developed.