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Glycosyl triazoles have been introduced as efficient ligands for the Cu-catalyzed Sonogashira reaction to overcome the challenges of sideways homocoupling reactions in Cu catalysis in this reaction. The atmospheric oxygen in a sealed tube did not affect t

A new strategy is presented to obtain an efficient heterogeneous gold catalyst constituted by isolated ionic gold sites, which is known to be effective in alkyne coupling reaction. The procedure is based on a significant difference between offered gold amount and available adsorbent sites on the support, ensuring the formation of very active isolated gold ion sites. In order to achieve this purpose, mesoporous silica xerogel was grafted with an ionic silsesquioxane containing charged ammonium quaternary group. The modified silica showed 0.25 mmol of cationic sites per gram of material and presented thermal stability up to 200 °C. This material was applied as support for immobilization of Au(III) ions as square planar AuCl4? complex. The gold amount offered was just 12 % of the exchangeable capacity. The catalyst was efficiently applied in the cross coupling reactions, in which only 0.22 mol% was applied to obtain symmetric and non-symmetric 1,3-diynes.

Due to the high oxidation potential between AuI and AuIII, gold redox catalysis requires at least stoichiometric amounts of a strong oxidant. We herein report the first example of an electrochemical approach in promoting gold-catalyzed oxidative coupling of terminal alkynes. Oxidation of AuI to AuIII was successfully achieved through anode oxidation, which enabled facile access to either symmetrical or unsymmetrical conjugated diynes through homo-coupling or cross-coupling. This report extends the reaction scope of this transformation to substrates that are not compatible with strong chemical oxidants and potentiates the versatility of gold redox chemistry through the utilization of electrochemical oxidative conditions.

Abstract: Copper nanoparticle on polyaniline support was synthesised by using in situ polymerisation and composite formation technique. This metal polymer nanocomposites material is found to be efficient for homocoupling of terminal alkynes which afford s

A new hydrophobic ester functionalized task specific ionic liquid has been synthesized and its application explored in the synthesis of conjugated 1,3-diynes through Glaser coupling of terminal alkynes. Terminal alkynes undergo oxidativecoupling smoothly

Bisphosphorylallenes were easily obtained in multigram scale from the Wittig-type rearrangement of bispropargyl alcohols. Unlike other conjugated bis-allenes, these reagents underwent a double cyclization mediated by iodine or copper dibromide leading to the formation of bis-1,2-oxaphospholenes.

A straightforward and efficient method has been demonstrated for the oxidative coupling of terminal alkynes using a simple Cu3(BTC)2-metal organic framework as a sustainable heterogeneous copper catalyst. A series of symmetrical 1,3-diynes bearing diverse functional groups have been synthesized in moderate to excellent yields via a Cu3(BTC)2 catalyzed Glaser-Hay reaction. The presence of the coordinatively unsaturated open CuII sites in Cu3(BTC)2 catalyzes the homocoupling in the presence of air, as an environment friendly oxidant without the use of external oxidants, ligands or any additives. The present methodology avoids stoichiometric reagents and harsher or special reaction conditions, and shows good functional group tolerance. The as-prepared catalyst could be separated easily by simple filtration and reused several times without any notable loss in activity. The hot filtration test has investigated the true heterogeneity of the catalyst. Additionally, the powder X-ray diffraction pattern of the reused catalyst revealed the high stability of the catalyst.

Mild reaction conditions for the Cadiot-Chodkiewicz cross coupling process have been developed for the highly selective and efficient synthesis of unsymmetrical diynes. The most abundant, economic, environmentally friendly, green solvent, water was employed as the sole reaction medium in combination with a minimal amount (5 equiv.) of piperidine base. The reported new reaction conditions provide operational simplicity, high selectivity for hetero coupling (>97%), use of water, and low basicity of the reaction medium compared to commonly used highly basic conditions, i.e., 30-70% amine in water or 100% piperidine. Various sensitive functional groups were found to be highly compatible with the developed low basic reaction conditions. This study supports the fact that the Cadiot-Chodkiewicz cross coupling can be a greener reaction, has a very broad substrate scope, but has always been employed in non-green highly basic conditions and with limited substrate scope.

A reusable ionic liquid 1-butyl-3-methylimidazolium bromide/Cu(II) system was proven to be a reusable catalyst for the homocoupling of terminal alkynes at mild temperature using air as oxidant in aqueous phase or under solvent-limited conditions. In most cases, good to excellent yields can be achieved, either aromatic alkynes or aliphatic alkynes were used as substrates. The homocoupling products 1,3-diynes were separated by extraction from the reaction system. And the activity of residue showed it could be reused for 3 and 6 cycles respectively under the aqueous phase conditions and solventlimited conditions. Furthermore, this reaction can be easily scaled up to gram level.

The synthesis of an easily accessible theophylline-derived copper complex with additional ammonium functionalization has been developed. This xanthine-based metal compound turned out to be an active initiator of the alkyne-azide cycloaddition reaction (CuAAC) and Glaser homo-coupling reaction in aqueous media at room temperature.

This communication describes the use of hypervalent iodine reagents to facilitate the homo-coupling of terminal alkynes. A variety of different aliphatic and aromatic alkynes were successfully dimerized when using acetoxy-benziodoxole as the activating agent under operationally simple transition metal-free conditions.

Application of a piperidine-appended dimethyl-imidazolium-NTf2 ionic liquid as dual solvent and base in the Sonogashira cross-coupling reaction of aryl-iodides with terminal acetylenes under mild conditions has been demonstrated. The method employs PdCl2(PPh3)2 without copper and external base. It is applicable to the synthesis of SF5-substituted diaryl- and aryl-alkyl-acetylenes, and can also be utilized for efficient homo-coupling of terminal acetylenes under aerobic conditions. The potential for recycling and reuse of this designer-IL offers an added advantage.

Nonafluorobutanesulfonyl azide is a highly efficient reagent for the copper-catalyzed coupling of terminal alkynes to give symmetrical and unsymmetrical 1,3-diynes in good to excellent yields and with good functional group compatibility. The reaction is e

A Cu(ii) complex has been heterogenized on SBA-15 by functionalization of SBA-15 with (N1-propylethane-1,2-diamine) triethoxysilane (NN-SBA-15) followed by anchoring of 2-pyridinecarboxaldehyde through Schiff's base formation between the terminal -NH

Homocoupling of terminal alkynes to 1,3-diynes has been investigated with Cu(II)-modified clay under mild and operationally simple conditions without the use of any ligand or a stabilizing agent. The catalyst is robust, ecofriendly, efficient, furnishes g

The oxidative Glaser-Hay coupling reaction of terminal alkynes is a very important reaction in organic chemistry to achieve the synthesis of diyne compounds. In general the reaction is performed under homogeneous conditions using Cu(I) or Cu(II) salts in the presence of a reagent such as tetramethylethylenediamine (TMEDA), which can bind to copper ions, an organic base and dioxygen. Although this reaction is known for a long time, the mechanism is still under discussion. Pursuing our investigations on the use of apatites as catalysts for organic reactions we highlight in this work how it is possible to catalyze the Glaser-Hay reaction under heterogeneous conditions using a Cu-modified hydroxyapatite (Cu-HAp). With several para-substituted phenyl-acetylenes and alkynols we show that Cu-HAp acts as catalyst for CC coupling reactions leading to diyne derivatives in high yields without using auxiliary chelating molecules and organic bases. These heterogeneous conditions allow an easy recovery of the catalyst and simplify the purification work-up.

A family of polymer-attached phenanthrolines was prepared from solvothermal copolymerization of divinylbenzene with N-(1,10-phenanthroline-5-yl)acrylamide in different ratios. The polymer-supported copper catalysts were obtained through typical impregnation with copper(II) salts. The polymers and supported copper catalysts have been characterized by N2 adsortion, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TG); they exhibit a high surface area, hierarchical porosity, large pore volume, and high thermal and chemical stabilities. The copper catalyst has proved to be highly active for Glaser homocoupling of alkynes and Huisgen 1,3-diolar cycloaddition of alkynes with benzyl azide under mild conditions at low catalyst loading. The heterogeneous copper catalyst is more active than commonly used homogeneous and nonporous polystyrene-supported copper catalysts. In particular, the catalyst is easily recovered and can be recycled at least ten times without any obvious loss in catalytic activity. Metal leaching was prevented due to the strong binding ability of phenanthroline and products were not contaminated with copper, as determined by ICP analysis. At the Copper, Coppercabana: Stable, porous polymer-attached phenanthrolines were successfully prepared from solvothermal copolymerization of divinylbenzene with N-(1,10-phenanthrolin-5-yl)acrylamide (PCP-Phen). After coordination with copper species, a heterogeneous copper catalyst was obtained that displayed a higher activity in Glaser and Huisgen couplings than commonly used homogeneous and nonporous polystyrene-supported copper catalysts. The copper catalyst has excellent recyclability due to the strong coordination ability of phenanthrolines. Copyright

A mild and efficient method for the synthesis of functionalized 1,5-dien-3-ynes from 1,3-diynes under PdII catalysis is described. The process allows quick and atom-economical assembly of various dihalo-, haloacyl-, and diacyl-substituted 1,5-dien-3-ynes in high yields. The switch of selectivity in the formation of these dienyne products can be controlled by the choice of catalysis system and reaction conditions.

Palladium-catalyzed oxidative homocoupling of terminal acetylenes, in air, occurred in the presence of 1-(2-pyridylethynyl)-2-(2-thienylethynyl)benzene as ligand, affording the corresponding conjugated diynes.

Supported Ionic Liquid Phase (SILP) catalysts have been prepared by effective immobilization of [Cu(TMEDA)(OH)]Cl in a nano-metric film of an ionic liquid on various oxidic support materials. The catalysts were tested for the oxidative homocoupling of 1-a

A practical oxidative homo- and heterocoupling of terminal alkynes was achieved in CH2Cl2 at 25 °C by using a 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized copper(I) complex (MCM-41-2N-CuI, 1 mol-%) as the catalyst, piperidine (0.1 or 3 equiv.) as the base, and air as the environmentally friendly co-oxidant, yielding a variety of symmetrical and unsymmetrical 1,4-disubstituted 1,3-diynes in good to excellent yields. This heterogeneous copper catalyst showed a higher catalytic activity than CuI and can be recovered and recycled by a simple filtration of the reaction mixture and used for at least 10 consecutive runs without any decrease in activity. A practical oxidative homo- and heterocoupling of terminal alkynes was achieved in CH2Cl2 at 25 °C by using a 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized copper(I) complex (MCM-41-2N-CuI, 1 mol-%) as the catalyst and air as the environmentally friendly oxidant, yielding a variety of symmetrical and unsymmetrical 1,4-disubstituted 1,3-diynes in good to excellent yields.

Solkane 365 mfc is proven to be an environmentally benign alternative solvent for the homocoupling reaction of terminal alkynes catalyzed by CuCl/TMEDA under air at room temperature. A variety of terminal alkynes, including aromatic, heteroaromatic and aliphatic alkynes, were cleanly transformed into 1,3-diynes within a short period in high to excellent yields up to 98%. The Royal Society of Chemistry.

Homocoupling of terminal alkynes has been efficiently achieved using catalytic amounts of CuCl2 and DBU. This methodology could be extended to couple two different terminal alkynes together by taking one of the alkyne partners, preferably the electron rich alkyne, in five fold excess than the other. CSIRO 2011.

A facile and efficient pathway for the copper iodide and ligand N,N,N',N'-tetramethylethane-1,2-diamine promoted homocoupling reaction of terminal alkynes under ambient temperature and air as an oxidant was reported. The alkynes, including aromatic alkynes and aliphatic alkynes, could afford the symmetrical 1,4-disubstituted 1,3-diynes in good to excellent yields. Copyright

Copper nanoparticles on titania effectively catalyse the oxidative homocoupling of terminal alkynes in the presence of piperidine as a base in tetrahydrofuran (THF) or under solvent-free conditions. A wide range of diynes have been synthesised in high yie

The di-copper-substituted γ-Keggin-type silicotungstate TBA 4[γ-H2SiW10O36Cu 2(μ-1,1-N3)2] (I, TBA = tetra-n- butylammonium) could act as an efficient reusable homogeneous catalyst for the aerobic oxidative alkyne homocoupling. Various kinds of structurally diverse terminal alkynes including aromatic, heteroaromatic, aliphatic, double bond-containing, silylacetylene, propargylic alcohol, and propargylic amine derivatives could selectively be converted into the corresponding diynes in the presence of I. The catalytic activity of I was much higher than those of the mono-copper-substituted silicotungstate, monomeric copper complexes, and simple copper salts, showing that the di-copper core in I plays an important role in the present alkyne homocoupling. The reaction mechanism involving the formation of the di-copper(II)-alkynyl intermediate, reductive elimination of a diyne, and re-oxidation of reduced copper species by O2 has been proposed.

Self-assembled tubular silica-based nanostructures can be prepared using a simple, low-energy intensive and benign protocol under mild conditions (100 °C) using microwave irradiation and conventional heating. These nanotubes were found to contain metal nanoparticles that are catalytically active in the microwave-assisted homocoupling of terminal alkynes. The Royal Society of Chemistry 2010.

(Chemical Equation Presented) The efficient Cu(I)-catalyzed oxidative homocoupling of terminal alkynes in the presence of a base using an amine as a ligand and oxygen as an oxidant yields the symmetrical 1,3-diynes with yields of up to 99%. The outcome of the couplings critically depends on the proper choice of base and ligand as well as reaction conditions. Best results were observed with 2.0 mol%CuCl, 1.5 mol%TMEDA or DBEDA, and DBU or DABCO in acetonitrile.

A simple copper promoting system CuI/NBS/DIPEA was first found to efficiently promote Glaser coupling reaction under ambient temperature. The alkynes with sensitive groups such as acetal and ketal, TBDMS, ester and amide could react smoothly to afford the

A new route to synthesize symmetrical 1,3-butadiynes from iodoacetylenes in the presence of copper powder and pyridine was developed. Moderate to excellent yields were obtained through an efficient and simple process involving the copper powder without any further activation. Copyright Taylor & Francis Group, LLC.

(Chemical Equation Presented) It goes on the dicopper core! A monomeric γ-Keggin silicotungstate with a dicopper core that is bridged by two μ-1,1-azido ligands catalyzes oxidative alkyne homocoupling reactions whereby various kinds of aromatic and aliphatic alkynes are selectively converted into the corresponding diynes (see picture).

The di-copper-substituted γ-Keggin silicotungstate with bis-μ-1,1-azido ligands TBA4[γ-H2SiW10O36Cu2(μ-1,1-N3)2] (1, TBA = tetra-n-butylammonium) was synthesized in an aqueous medium. The crystal structure of the anion part of 1 was a monomer of the basal-basal end-on diazido-bridged di-copper-substituted γ-Keggin silicotungstate. The NMR and CSI-MS spectra of 1 in organic solvents, such as acetonitrile, benzonitrile, and 1,2-dichloroethane, showed that complex 1 was present as a monomer of the di-copper-substituted γ-Keggin silicotungstate. Complex 1 could act as an effective homogeneous catalyst for the oxidative homocoupling of various types of alkynes, including aromatic, aliphatic, and heteroatom-containing ones. The reaction possibly proceeds as follows: First, the ligand exchange proceeds between the azido groups in 1 and alkynyl groups to form the corresponding diyne with the reduced copper(I) species via the di-copper(II)-alkynyl intermediate, then the reduced species is reoxidized by molecular oxygen, and the oxidized species reacts with an alkyne to regenerate the alkynyl intermediate.

A novel pathway for homocoupling of terminal alkynes has been described using cyclopalladated ferrocenylimine 1 or 2/CuI as catalyst in the air. This catalytic system could tolerate several functional groups. The palladacycle 2 in the presence of n-Bu4NBr as an additive could be applied to Sonogashira cross-coupling reaction of aryl iodides, aryl bromides, and some activated aryl chlorides with terminal alkynes under amine- and copper-free conditions, mostly to give moderate to excellent yields.

A basic ionic liquid was selected to serve as both the solvent and base for Heck, "copper-free" Sonogashira reactions, and for homocoupling reactions of terminal alkynes. The ionic liquids with tertiary aliphatic amines are effective solvents for these reactions. Under reflux conditions, eight equivalent basic ionic liquids and Pd(OAc)2 in THF or acetone produced palladium colloids with diameters of (2.6±0.3) or (3.7±0.5) nm, respectively. Preliminary results for Knoevenagel condensations are also reported. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

An efficient method for palladium-catalyzed homocoupling reaction of terminal alkynes in the synthesis of symmetric diynes is presented. The results showed that both Pd(OAc)2 and CuI played crucial roles in the reaction. In the presence of 2 mo

An efficient, amine- and phosphine-free palladium(II)-catalyzed homocoupling of terminal alkynes has been developed. In the presence of PdCl2, CuI, Me3NO, and NaOAc, homocoupling of various terminal alkynes underwent smoothly to affo

An efficient, room temperature procedure for the cross-coupling of a range of terminal alkynes, using standard Sonogashira cross-coupling conditions (Pd/Cu) is presented. At higher reaction temperatures, head-to-tail or head-to-head dimerisation affords 1,3- and 1,4-disubstituted enynes, respectively as minor products.

A novel pathway for the homocoupling reaction has been achieved using a similar protocol as the cross-coupling reaction. Ethyl bromoacetate is chosen to initiate the coupling reaction through oxidatlve addition to a Pd(0) species, and an PdBr(enolate) intermediate is formed. This intermediate can undergo double transmetalation with an alkynyl copper reagent, and reductive elimination produces a variety of diynes in high yields.