Homocoupling Reaction Of Terminal Alkynes Research Articles

Facile preparation of surface-oxidized nanoporous Pd for homocoupling reaction

Surface-oxidized nanoporous Pd (SO NP Pd) catalyst was prepared easily from nanoporous Pd, which was dealloyed from a NiPdP glass. 1,3-Diynes were synthesized in high to excellent yields through the homocoupling of terminal acetylenes using SO NP Pd prepared at 250 °C in air. The presence of Pd (II) in the surface-oxidized layer was crucial for the homocoupling reaction of terminal alkynes.

Cobalt‐Catalyzed Dimerization and Homocoupling of Terminal Alkynes

AbstractMethods toward the dimerization and homocoupling of terminal alkynes have been established that employ Co complexes along with tBuOK under different atmosphere. A variety of Z‐1,3‐enynes were furnished with a high Z:E (up to 93:7) ratio in moderate to very good yields under inert atmosphere. Alternatively, the Glaser homocoupling reaction of terminal alkynes was also accomplished with a Co catalyst, successfully affording various 1,3‐diynes in excellent yields (up to 93 %) under oxygen.

An Elastic Monolithic Catalyst: A Microporous Metalloporphyrin-Containing Framework-Wrapped Melamine Foam for Process-Intensified Acyl Transfer.

The advent of conjugated microporous polymers (CMPs) has had significant impact in catalysis. However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of CMPs in catalytic reactions. Herein, the preparation of a foam-supporting CMP composite with interconnective micropores and macropores and elastic properties is reported. Metalloporphyrin-based CMP organogels are synthesized within the melamine foam by a room-temperature oxidative homocoupling reaction of terminal alkynes. Upon drying, the CMP-based xerogels tightly wrap the framework skeletons of the foam, while the foam cells are still open to allow for the preservation of elasticity and macroporosity. Such a hierarchical structure is efficient for acyl transfer, facilitates substrate diffusion within interpenetrative macropores and micropores, and could be used to intensify catalytic processes.

An Elastic Monolithic Catalyst: A Microporous Metalloporphyrin‐Containing Framework‐Wrapped Melamine Foam for Process‐Intensified Acyl Transfer

AbstractThe advent of conjugated microporous polymers (CMPs) has had significant impact in catalysis. However, the presence of only micropores in these polymers often imposes diffusion limitations, which has resulted in the low utilization of CMPs in catalytic reactions. Herein, the preparation of a foam‐supporting CMP composite with interconnective micropores and macropores and elastic properties is reported. Metalloporphyrin‐based CMP organogels are synthesized within the melamine foam by a room‐temperature oxidative homocoupling reaction of terminal alkynes. Upon drying, the CMP‐based xerogels tightly wrap the framework skeletons of the foam, while the foam cells are still open to allow for the preservation of elasticity and macroporosity. Such a hierarchical structure is efficient for acyl transfer, facilitates substrate diffusion within interpenetrative macropores and micropores, and could be used to intensify catalytic processes.

Gelation of Metalloporphyrin-Based Conjugated Microporous Polymers by Oxidative Homocoupling of Terminal Alkynes

A Pd(II)/Cu(I) cocatalyzed homocoupling reaction of terminal alkynes to diynes was used to synthesize conjugated polymer organogels with tetragonal topological frameworks consisting of Zn-porphyrin units as nodes and diynes as struts. This material appears fibrous with a micrometer length, possesses outstanding elastic properties, and could be organized into desired modules. Upon drying, the transformed xerogels afford superior thermal stability and microporosity, implying that they are supported by conjugated microporous polymer (CMP) skeletons at the molecular level. The microporosity of CMP-structured xerogels could be adjusted by varying the monomer concentrations, reaction temperatures and solvent species. The notable narrowed pore size distribution is achieved under optimal conditions, which results in CMP-supported xerogels outperforming the most reported CMPs, although the networks are still amorphous in nature. By following the same synthesis route, for the first time, the interpenetrating polymer network organogels were prepared by forming two CMP components sequentially in a temperature-controlled manner and in one pot. This provides an unprecedented combination of multiple interwoven CMP modules whose functions could be assembled synergistically for prospective broader applications.

Copper(I)-catalyzed homocoupling reaction of terminal alkynes in supercritical CO2

An efficient method for CuCl-catalyzed homocoupling reaction of terminal alkynes in the synthesis of symmetric 1,3-diynes has been developed in supercritical CO2 (ScCO2) without organic solvent. Homocoupling of various terminal alkynes (solid or liquid) could afford the corresponding products in moderate to excellent yields. In addition, ScCO2 play the role of reactive solvent, and DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) acts as the key additive for homocoupling reactions of terminal alkynes, which enhanced the reaction rate and the solubility of copper(I) catalyst in ScCO2.

Ligand‐Free Synthesis of 1,4‐Disubstituted‐1,3‐diynes by Iron/Copper Cocatalyzed Homocoupling of Terminal Alkynes

AbstractA simple and efficient protocol for Fe/Cu cocatalyzed oxidative homocoupling reaction of terminal alkynes to symmetrical 1,4‐disubstituted‐1,3‐diynes was presented. The results showed that both CuBr and FeCl3 played crucial roles in the reaction. It is noteworthy that this protocol employs mild, efficient, aerobic and ligand free conditions. The alkynes, including aromatic, heteroaromatic and aliphatic alkynes, were transformed into the corresponding 1,3‐diynes in good to excellent yields.

ChemInform Abstract: Organic Reaction in Solkane® 365 mfc: Homocoupling Reaction of Terminal Alkynes.

AbstractSolkane® 365 mfc is proved to be an environmentally benign alternative solvent for the homocoupling reaction of terminal alkynes (I) under air to afford 1,3‐diynes (II) in high yields.

An Efficient Copper‐Catalyzed Homocoupling of Terminal Alkynes to Give Symmetrical 1,4‐Disubstituted 1,3‐Diynes

AbstractA 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.

A reusable CuSO4 · 5H2O/cationic 2,2′-bipyridyl system catalyzed homocoupling of terminal alkynes in water

A reusable CuSO4 · 5H2O/cationic 2,2′-bipyridyl system catalyzed the homocoupling reaction of terminal alkynes in water using I2 as the additive in the presence or absence of tetrabutylammonium bromide, giving the 1,3-diynes in good to high yields. After reaction, the residual aqueous solution could be reused several times. Copyright © 2011 John Wiley & Sons, Ltd.

1,3-Diynes synthesis by homo-coupling of terminal alkynes using a Pd(PPh 3) 4/Ag 2O simple catalyst system

Amine- and copper salt-free palladium-catalyzed homo-coupling reaction of terminal alkynes proceeded efficiently in the presence of silver(I) oxide, which served as both activator and oxidant, in tetrahydrofuran at 60 °C to achieve satisfactory yields of 1,3-diyne compounds. It was demonstrated for the first time by means of XPS analysis that Pd(0) species can be oxidated to Pd(II) by silver(I) oxide.

Organic reaction in Solkane® 365 mfc: homocoupling reaction of terminal alkynes

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%.

CuI‐catalyzed homocoupling of terminal alkynes to 1,3‐diynes

AbstractA simple and efficient protocol for CuI‐catalyzed oxidative homocoupling reaction of terminal alkynes to symmetrical 1,4‐disubstituted 1,3‐diynes was reported. The reaction can be carried out in the open air, using NaOAc as a base in the absence of any other additives. A variety of terminal alkynes were converted to the corresponding 1.3‐diynes in good to excellent yields without any side product formation. Copyright © 2010 John Wiley & Sons, Ltd.

Iron/copper promoted oxidative homo-coupling reaction of terminal alkynes using air as the oxidant

An inexpensive catalytic system, which used a readily available Fe(acac) 3 and trace quantity of Cu(acac) 2 as the co-catalyst and air as the oxidant for the homo-coupling of terminal alkynes, has been developed. The catalytic system could also apply to the cross-coupling reaction of two different terminal alkynes.

Palladium acetate complexes bearing chelating N-heterocyclic carbene (NHC) ligands: Synthesis and catalytic oxidative homocoupling of terminal alkynes

The imidazolium salts 1,1′-dibenzyl-3,3′-propylenediimidazolium dichloride and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazolium dichloride have been synthesized and transformed into the corresponding bis(NHC) ligands 1,1′-dibenzyl-3,3′-propylenediimidazol-2-ylidene (L 1) and 1,1′-bis(1-naphthalenemethyl)-3,3′-propylenediimidazol-2-ylidene (L 2) that have been employed to stabilize the Pd II complexes PdCl 2(κ 2- C, C-L 1) ( 2a) and PdCl 2(κ 2- C, C-L 2) ( 2b). Both latter complexes together with their known homologous counterparts PdCl 2(κ 2- C, C-L 3) ( 1a) (L 3 = 1,1′-dibenzyl-3,3′-ethylenediimidazol-2-ylidene) and PdCl 2(κ 2- C, C-L 4) ( 1b) (L 4 = 1,1′-bis(1-naphthalenemethyl)-3,3′-ethylenediimidazol-2-ylidene) have been straightforwardly converted into the corresponding palladium acetate compounds Pd(κ 1- O-OAc) 2(κ 2- C, C-L 3) ( 3a) (OAc = acetate), Pd(κ 1- O-OAc) 2(κ 2- C, C-L 4) ( 3b), Pd(κ 1- O-OAc) 2(κ 2- C, C-L 1) ( 4a), and Pd(κ 1- O-OAc) 2(κ 2- C, C-L 2) ( 4b). In addition, the phosphanyl-NHC-modified palladium acetate complex Pd(κ 1- O-OAc) 2 (κ 2- P, C-L 5) ( 6) (L 5 = 1-((2-diphenylphosphanyl)methylphenyl)-3-methyl-imidazol-2-ylidene) has been synthesized from corresponding palladium iodide complex PdI 2(κ 2- P, C-L 5) ( 5). The reaction of the former complex with p-toluenesulfonic acid ( p-TsOH) gave the corresponding bis-tosylate complex Pd(OTs) 2(κ 2- P, C-L 5) ( 7). All new complexes have been characterized by multinuclear NMR spectroscopy and elemental analyses. In addition the solid-state structures of 1b·DMF, 2b·2DMF, 3a, 3b·DMF, 4a, 4b, and 6·CHCl 3·2H 2O have been determined by single crystal X-ray structure analyses. The palladium acetate complexes 3a/ b, 4a/ b, and 6 have been employed to catalyze the oxidative homocoupling reaction of terminal alkynes in acetonitrile chemoselectively yielding the corresponding 1,4-di-substituted 1,3-diyne in the presence of p-benzoquinone (BQ). The highest catalytic activity in the presence of BQ has been obtained with 6, while within the series of palladium-bis(NHC) complexes, 4b, featured with a n-propylene-bridge and the bulky N-1-naphthalenemethyl substituents, revealed as the most active compound. Hence, this latter precursor has been employed for analogous coupling reaction carried out in the presence of air pressure instead of BQ, yielding lower substrate conversion when compared to reaction performed in the presence of BQ. The important role of the ancillary ligand acetate in the course of the catalytic coupling reaction has been proved by variable-temperature NMR studies carried out with 6 and 7′ under catalytic reaction conditions.

CuI/iodine-mediated homocoupling reaction of terminal alkynes to 1,3-diynes

A facile and efficient pathway for CuI/iodine-mediated homocoupling reaction of terminal alkynes to symmetrical 1,4-disubstituted 1,3-diynes in good to excellent yields was reported.

Ligand- and Base-Free Synthesis of 1,3-Diynes Catalyzed by Low Loading of Heterogeneous Pd/C and CuI

A facile and environmentally friendly synthetic method for a variety of symmetrical 1,3-diyne derivatives based on the Pd/C-CuI-catalyzed homocoupling reaction of terminal alkynes has been developed. The reaction was efficiently catalyzed by the -extremely low loading (0.01-0.03 mol%) of Pd/C and CuI (3 mol%) in the presence of molecular oxygen (O 2) as an oxidant without any phosphine ligands and bases.

A new CuAl–hydrotalcite catalyzed homocoupling reaction of terminal alkynes at room temperature

AbstractCuAl–LDH has been prepared and applied, for the first time, in the homocoupling reaction of a variety of terminal alkynes at room temperature. The Cu (II) in the host layers of the hydrotalcite exhibits high activity and the catalyst can be easily recovered and reused for eight cycles without depreciation of catalytic activity. Copyright © 2007 John Wiley & Sons, Ltd.

Cu(II)‐Promoted Oxidative Homocoupling Reaction of Terminal Alkynes in Supercritical Carbon Dioxide.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cu(II)-Promoted Oxidative Homocoupling Reaction of Terminal Alkynes in Supercritical Carbon Dioxide

Oxidative homocoupling reaction of various terminal alkynes in supercritical carbon dioxide (scCO 2 ) has been reported. The final optimized reaction conditions for the reaction in scCO 2 were determined to be cupric chloride (2 mmol), sodium acetate (2 mmol), methanol (1 mL) and CO 2 (14 MPa) at 40 °C. Sodium acetate was superior to pyridine in the present reaction system. Methanol, as a co-solvent of scCO 2 , was necessary to help dissolve the inorganic salt and facilitated the reaction. Higher solubility of cupric chloride in the scCO 2 -methanol medium than other cupric salts, e.g. CuSO 4 , Cu(NO 3 ) 2 , Cu(OAc) 2 and cupric bromide, guaranteed its high catalytic ability. Variations of the pressure of seCO 2 and temperature in a certain range have almost little impact on the reaction efficiency. A mechanism involving copper(II)-acetylide complex was supposed in which AcO - or Cl - instead of N-containing compounds acted as ligands. The reaction system in scCO 2 is an effective and environmental-friendly alternative to the previous methods of homocoupling of terminal alkynes involving volatile organic compounds.