Aliphatic Alkynes Research Articles

Silver-Free Direct Synthesis of Alkynylphosphine Oxides via spC-H/P(O)-H Dehydrogenative Coupling Catalyzed by Palladium.

A silver-free palladium-catalyzed dehydrogenative phosphorylation of terminal alkynes with hydrogen phosphine oxides has been developed. Both aromatic and aliphatic terminal alkynes including those bearing functional groups coupled readily with hydrogen phosphine oxides, producing the corresponding value-added alkynylphosphine oxides in good to excellent yields. This reaction could be easily conducted at gram scales (10 mmol) without any decrease of the reaction efficiency, showing highly potential synthetic value in organic synthesis. A plausible Pd(0)/Pd(II) mechanism is proposed.

A3‐Coupling Reaction and [Ag(IPr)2]PF6: A Successful Couple

The recently described homoleptic cationic [Ag(IPr)2]PF6 [IPr = 1,3‐bis(2,6‐diisopropylphenyl)imidazolylidene] complex proved to be a versatile and highly efficient catalyst for the production of propargylamines by using the A3‐coupling reaction. The reaction conditions were equally applicable to aliphatic and aromatic aldehydes and alkynes, including highly hindered aromatic aldehydes. Propargylamines were prepared in short reaction times with low catalyst loadings by using MeOH as a low‐toxicity solvent. In addition, the catalyst was stable enough to support continuous‐flow conditions, which showed that the reaction conditions are scalable.

Room Temperature Multicomponent Polymerizations of Alkynes, Sulfonyl Azides, and Iminophosphorane toward Heteroatom-Rich Multifunctional Poly(phosphorus amidine)s

Multicomponent polymerization (MCP) is a fascinating synthetic method for the construction of polymers with diverse structures and multifunctionalities. As a rapidly developing field, MCP begins to show great impact in polymer chemistry and polymer materials, which attract scientists’ attention by their high convenience and efficiency, great structure diversity, high atom economy, and environmental benefit. In this work, a facile one-pot three-component polymerization of diynes, disulfonyl azides, and iminophosphorane is developed to construct N, O, S, and P-containing heteroatom-rich poly(phosphorus amidine)s with advanced functionalities. The optimized MCP proceeds at room temperature in THF under the catalysis of CuI, generating polymers with high molecular weights (up to 85 600 g/mol) in excellent yields (up to 92%). The MCP enjoys general applicability of various monomers including aromatic and aliphatic alkynes, and the only byproduct generated from the polymerization is nitrogen gas, demonstrating high atom economy and environmental benefit. Interestingly, the phosphorus amidine model compounds were found to possess both aggregation-induced emission behavior and thermally activated delayed fluorescence, indicating unique feature of the corresponding polymer materials. The polymers generally enjoy good solubility in polar organic solvents, good film-forming ability, satisfactory thermal stability, and high refractivity. They can also function as fluorescent chemosensors for Pd2+ ions detection with high sensitivity (Kq up to 207 600 M–1) and selectivity. This MCP provides an efficient approach for the synthesis of heteroatom-rich multifunctional polymer materials, which directly construct the luminescent phosphorus amidine moiety in situ, demonstrating high synthetic efficiency and the potential application in material science.

Catalytic Coupling between Unactivated Aliphatic C-H Bonds and Alkynes via a Metal-Hydride Pathway.

We report a Rh(I)-catalyzed site-selective coupling between ketone β-C(sp3)-H bonds and aliphatic alkynes using an in situ-installed directing group. Upon hydrogenation or hydration, various β-alkylation or β-aldol products of the ketones are obtained with broad functional group tolerance. Mechanistic investigations support the involvement of a Rh-H intermediate through oxidative addition of Rh(I) into the β-C-H bonds. Thus, to the best of our knowledge, this transformation represents the first example of catalytic couplings between unsaturated hydrocarbons and unactivated aliphatic C-H bonds via a metal-hydride pathway.

Disassembling Metal Nanocrystallites into Sub‐nanometric Clusters and Low‐faceted Nanoparticles for Multisite Catalytic Reactions

AbstractMetal nanocrystallites present saturated atoms, in planes, and unsaturated metal atoms, in corners and vertices, for catalytic applications. However, both sites are spatially complementary and simultaneously excluding for a given particle, thus their number cannot be independently maximized for a catalytic process. Here, it is shown that the independent dosage of Au clusters and metallic Au nanoparticles dramatically improves the catalytic activity of Au for the Sonogashira reaction, enabling the coupling of a wide range of iodo‐, bromo‐, and activated chloro‐derivatives with aromatic and aliphatic alkynes, and outperforming ligand‐free Pd and Cu catalysts. Mechanistic studies reveal that the unsaturated atoms of the cluster activate the alkyne and that the saturated atoms of the metallic nanoparticle preferentially activate the halide, to finally perform the coupling. Thus, a precise combination of sub‐nanometric metal clusters and metal nanoparticles, together, constitute a new catalytic strategy to substitute metal nanocrystallites in reactions in which both unsaturated and saturated atoms play a key role.

MIL-101(Cr)-SO3Ag: An efficient catalyst for solvent-free A3 coupling reactions

An Ag(I)-functionalized MOF, MIL-101-SO3Ag, was synthesized and demonstrated to be an efficient and environmentally friendly catalyst for the syntheses of propargylamines through A3 coupling of aldehydes, terminal alkynes and amines. A quite small amount of the catalyst can efficiently catalyze the reactions of aliphatic aldehydes, alkynes, and amines under solvent-free conditions to give propargylamines in excellent yields (>90%). The TOF can be as high as 6600h−1. The catalytic efficiency is higher than other catalysts available in the literature. The catalyst could be easily recycled without a significant loss of its catalytic activity. In addition, we found that the catalyst also promotes the secondary reaction in which the propargylamines formed from aromatic aldehydes undergo propargyl-to-allenyl isomerization and subsequent hydrolysis to give chalcones.

Direct Functionalization of an Acid-Terminated Nanodiamond with Azide: Enabling Access to 4-Substituted-1,2,3-Triazole-Functionalized Particles

Azides on the periphery of nanodiamond materials (ND) are of great utility because they have been shown to undergo Cu-catalyzed and Cu-free cycloaddition reactions with structurally diverse alkynes, affording particles tailored for applications in biology and materials science. However, current methods employed to access ND featuring azide groups typically require either harsh pretreatment procedures or multiple synthesis steps and use surface linking groups that may be susceptible to undesirable cleavage. Here we demonstrate an alternative single-step approach to producing linker-free, azide-functionalized ND. Our method was applied to low-cost, detonation-derived ND powders where surface carbonyl groups undergo silver-mediated decarboxylation and radical substitution with azide. ND with directly grafted azide groups were then treated with a variety of aliphatic, aromatic, and fluorescent alkynes to afford 1-(ND)-4-substituted-1,2,3-triazole materials under standard copper-catalyzed cycloaddition conditions. Surface modification steps were verified by characteristic infrared absorptions and elemental analyses. High loadings of triazole surface groups (up to 0.85 mmol g-1) were obtained as determined from thermogravimetric analysis. The azidation procedure disclosed is envisioned to become a valuable initial transformation in numerous future applications of ND.

Cobalt‐Catalyzed Z‐Selective Hydrosilylation of Terminal Alkynes

AbstractA cobalt‐catalyzed Z‐selective hydrosilylation of alkynes has been developed relying on catalysts generated from bench‐stable Co(OAc)2 and pyridine‐2,6‐diimine (PDI) ligands. A variety of functionalized aromatic and aliphatic alkynes undergo this transformation, yielding Z‐vinylsilanes in high yields with excellent selectivities (Z/E ratio ranges from 90:10 to >99:1). The addition of a catalytic amount of phenol effectively suppressed the Z/E‐isomerization of the Z‐vinylsilanes that formed under catalytic conditions.

Cobalt‐Catalyzed Z‐Selective Hydrosilylation of Terminal Alkynes

A cobalt-catalyzed Z-selective hydrosilylation of alkynes has been developed relying on catalysts generated from bench-stable Co(OAc)2 and pyridine-2,6-diimine (PDI) ligands. A variety of functionalized aromatic and aliphatic alkynes undergo this transformation, yielding Z-vinylsilanes in high yields with excellent selectivities (Z/E ratio ranges from 90:10 to >99:1). The addition of a catalytic amount of phenol effectively suppressed the Z/E-isomerization of the Z-vinylsilanes that formed under catalytic conditions.

Nickel-Catalyzed Stereoselective Alkenylation of C(sp3)-H Bonds with Terminal Alkynes.

A nickel-catalyzed stereoselective alkenylation of an unactivated β-C(sp3)-H bond in aliphatic amide with terminal alkynes using 8-aminoquinoline auxiliary is reported for the first time. This reaction displays excellent functional group tolerance with respect to both aliphatic amides and terminal alkynes and features a cheap nickel catalytic system. The 8-aminoquinolyl directing group could be smoothly removed, and the resultant β-styrylcarboxylic acid derivatives could serve as versatile building blocks for further transformation.

Hydration of aromatic terminal alkynes catalyzed by sulfonated condensed polynuclear aromatic (S-COPNA) resin in water

Hydration of aromatic terminal alkynes in the presence of a catalytic amount of sulfonated condensed polynuclear aromatic (S-COPNA) resin in water gave the corresponding methyl ketones in good yields. On the other hand, aliphatic terminal alkynes did not react at all under the employed conditions. Chemoselective hydration of aromatic terminal alkyne in the presence of aliphatic terminal alkyne catalyzed by S-COPNA resin was carried out.

Au-Cu core-shell nanocube-catalyzed click reactions for efficient synthesis of diverse triazoles.

Au-Cu core-shell nanocubes and octahedra synthesized in aqueous solution were employed to catalyze a 1,3-dipolar cycloaddition reaction between phenylacetylene and benzyl azide in water at 50 °C for 3 h. Interestingly, the nanocubes were far more efficient in catalyzing this reaction, giving 91% yield of a regioselective 1,4-triazole product, while octahedra only recorded 46% yield. The Au-Cu nanocubes were subsequently employed to catalyze the click reaction between benzyl azide and a broad range of aromatic and aliphatic alkynes. The product yields ranged from 78 to 99%. Clearly the Au-Cu cubes exposing {100} surfaces are an excellent and green catalyst for click reactions.

Biosynthesis of Silver Nano Particles from the Ethanolic Extract Fruits of Mallotus phillipensis

Objective: To develop a novel approach for the green synthesis of silver nanoparticles using Ethanolic extract of fruits of Mallotus phillipensis. Characterizations were determined by using ultraviolet-visible (UV-Vis) spectrophotometry, FTIR, scanning electron microscopy (SEM), and X-ray diffraction. The UV results showed the maximum absorption peak at range of 300-400nm. FTIR Showed the Presence of halides group, aliphatic amines group, alkenes group, alkynes, alcohols and phenol Groups. SEM showed the formation of silver nanoparticles with an average size of 30 - 100 nm. The typical XRD pattern revealed that the sample contains a mixed phase (cubic and hexagonal) structures of silver nanoparticles

Hydrophosphorylation of aliphatic alkynes catalyzed by CuNPs/ZnO for the synthesis of vinyl phosphonates. A DFT study on the reaction mechanism

A DFT study on the reaction mechanism for the synthesis of vinyl phosphonates catalyzed by CuNPs/ZnO. Essential role of the solvent and the catalyst support.

AuIII‐Catalyzed Formation of α‐Halomethyl Ketones from Terminal Alkynes

A AuIII‐catalyzed synthesis of α‐halomethyl ketones from terminal alkynes was developed. This approach features excellent functional group compatibility and good yields for both aromatic and aliphatic terminal alkynes. The resulting α‐halomethyl ketones were used to prepare heterocyclic indolizine structures. The plausible mechanism of the one‐pot reaction is proposed.

ChemInform Abstract: Synthesis of Unsymmetrical 1,3‐Diynes via Pd/Cu‐Catalyzed Cross‐Coupling of Terminal Alkynes at Room Temperature.

A facile and practical synthetic route of unsymmetrical 1,3-diynes via the PdCl/CuI catalyzed oxidative coupling of two different terminal alkynes has been developed by using 3-(diphenylphosphino)propanoic acid as a ligand in the presence of oxygen. This system is suitable for not only aromatic alkynes but also heteroaromatic and aliphatic alkynes which were transformed into the corresponding unsymmetrical 1,3-diynes in moderate to good yields at room temperature. Moreover, the unsymmetrical 1,3-diynes were also obtained on a multi-gram scale. Mechanistic studies suggest that oxygen plays a key role in the catalytic cycles.

A copper (I or II)/diethylphosphite catalytic system for base-free additive dimerization of alkynes

Copper (I) or copper (II) salts and oxides promote regioselective head-to-head additive dimerization of aromatic and aliphatic terminal alkynes in the presence a catalytic amount of diethylphosphite. The reaction proceeds under ambient conditions without any added base with the formation of 1,4-disubstituted 1,3-enynes with the E isomer as major product in good to excellent yields. A plausible mechanism for additive dimerization of terminal alkynes is proposed.

Gallic acid-derived palladium(0) nanoparticles as in situ-formed catalyst for Sonogashira cross-coupling reaction in ethanol under open air

A simple and eco-friendly protocol using gallic acid-derived palladium(0) nanoparticles as in situ-formed catalyst for Sonogashira reactions in ethanol under optimum thermal conditions have been developed. Excellent yields were obtained with the addition of a small amount of gallic acid (1mol%) to the reaction mixture. The formation of the PdNPs was confirmed by using UV/Vis spectroscopy, and their size and morphology were determined by TEM and XRD analysis. Both aliphatic and aromatic terminal alkynes displayed efficient reactivity with the catalytic system. Moreover, the reaction condition is highly compatible with less reactive aryl bromides at moderate temperature, and further can be reused repeatedly up to four cycles. Since gallic acid is a non-toxic naturally abundant phytochemical, the present method provides an efficient alternative route for Sonogashira reaction with natural feedstock as additive.

Synthesis of Difluorinated Enynes through Sonogashira-Type Coupling.

The Sonogashira-type coupling of 2,2-difluoroethenyl tosylate with a variety of aliphatic and aromatic terminal alkynes proceeds smoothly even at room temperature to produce the corresponding difluorinated enyne derivatives. 2,2-Difluoroethenyl tosylate is a useful difluoroethenyl source because of its ready availability from 2,2,2-trifluoroethanol. Some of the obtained enynes exhibit strong fluorescence in the solid state. Further derivatization of a difluorinated enyne through Rh(III)-catalyzed oxidative coupling has also been examined.

Enantioselective Direct Alkynylation of Ketones Catalyzed by Chiral CCN Pincer RhIII Complexes.

A direct asymmetric alkynylation of ketones with new chiral CCN Rh catalysts containing N-heterocyclic carbene and oxazoline hybrid ligands is described. The catalytic reaction of fluoroalkyl-substituted ketones, ArCOCF2 X (X=F, Cl, H), with aromatic and aliphatic alkynes yielded the corresponding chiral propargyl alcohols with high enantioselectivity. Control and kinetic experiments suggested a bis(alkynyl) Rh intermediate as the active species for the C-C bond-forming step.