Carboxylation Of Alkynes Research Articles

Carboxylation of terminal alkynes with CO2 using novel silver N-heterocyclic carbene complexes.

Four novel N-heterocyclic carbene (NHC) silver complexes, , have been synthesized and characterized. The single X-ray crystal diffraction data indicate a dinuclear solid-state structure for and and a mononuclear structure for and . These complexes have been successfully used as efficient catalysts for the C-H activating carboxylation of terminal alkynes with CO2. A wide range of substrates with various functional groups afforded the corresponding aryl or alkyl substituted propiolic acids in good yields under mild conditions. Moreover, the role of bases and the reaction mechanism is thoroughly discussed.

Copper(I)-based ionic liquid-catalyzed carboxylation of terminal alkynes with CO2 at atmospheric pressure

An ionic liquid containing copper(I) proved to be an effective homogeneous catalyst for the carboxylation of terminal alkynes with ambient CO2. This developed procedure needs no external ligands and terminal alkynes with various groups proceeded smoothly at atmospheric CO2 pressure and room temperature. Interestingly, the ILs containing copper(I) in both the anion and the cation showed much higher activity in comparison with the counterparts incorporating copper(I) solely in the form of halocuprate, that is, copper(I) in the anion. Especially, activated effect of the terminal alkyne by the ionic liquid was also validated by the NMR technique.

A Sequentially Copper-Catalyzed Alkyne Carboxylation–Propargylation–Azide Cycloaddition (CuACPAC) Synthesis of 1,2,3-Triazolylmethyl Arylpropiolates

Concatenation of copper-catalyzed alkyne carboxylation–alkylation and copper-catalyzed alkyne–azide cycloaddition gives a novel sequentially copper-catalyzed alkyne carboxylation–propargylation–azide cycloaddition (CuACPAC) process furnishing 1,2,3-triazolylmethyl arylpropiolates via a consecutive four-component synthesis. The CuACPAC can be expanded to a five-component synthesis of 1,2,3-triazolylmethyl 3-amino arylacrylates by a concluding Michael addition in the same pot.

ChemInform Abstract: Carboxylation of Terminal Alkynes with CO2 Catalyzed by Bis(amidate) Rare‐Earth Metal Amides.

AbstractThree bis(amidate) rare‐earth metal amides are synthesized (containing lanthanum, neodymium and yttrium) which are found to be efficient catalysts for the direct carboxylation of terminal alkynes with CO2.

Tuning redox potentials of CO2 reduction catalysts for carbon photofixation by Si nanowires

Si nanowires (SiNWs) are shown to absorb visible light to reduce Ni catalysts into Ni^0 compounds, enabling alkyne carboxylation reactions with CO_2 as a carbon feedstock. The reduced Ni catalysts are effective in CO_2 fixation through a 4-octyne carboxylation reaction. The reduction potentials of the Ni catalysts can be tuned from -1.35 to -0.51 V (vs. saturated calomel electrode) by altering the binding ligands. The results shed light on the nature of charge transfer from SiNWs to the catalyst for this new class of photocatalytic reactions. By controlling the CO_2 reduction potential of the catalysts with carefully ligand designs, it will bring more opportunities and options to realize the highly selective, effective and sustainable CO_2 reduction in the future.

Copper(I)@Carbon-Catalyzed Carboxylation of Terminal Alkynes with CO2 at Atmospheric Pressure

Activated carbon supported CuBr was found to be an efficient catalyst for the carboxylation of terminal alkynes under atmospheric pressure of CO2 using ethylene carbonate as solvent at 80 °C for only 2 h, as verified with 13CO2. Various terminal alkynes could react smoothly with CO2 and organic halides under the reaction conditions to afford the corresponding carboxylic esters. In addition, the catalyst can be easily recovered and reused at least five times without significant loss of activity.

Carboxylation of Terminal Alkynes with Carbon Dioxide Using Ag@MIL-101

Key words carbon dioxide - metal-organic frameworks - alkynes - silver nanoparticles - heterogeneous catalysis

ChemInform Abstract: Nickel‐Catalyzed Double Carboxylation of Alkynes Employing Carbon Dioxide.

AbstractThe Ni‐catalyzed double carboxylation of internal alkynes with CO2, affording highly versatile maleic anhydrides as products is reported.

ChemInform Abstract: Consecutive Three‐Component Synthesis of 2,6‐Disubstituted Pyrimid‐4(3H)‐ones and 1,5‐Disubstituted 3‐Hydroxypyrazoles Initiated by Copper(I)‐Catalyzed Carboxylation of Terminal Alkynes.

ChemInform Abstract: Consecutive Three‐Component Synthesis of 2,6‐Disubstituted Pyrimid‐4(3H)‐ones and 1,5‐Disubstituted 3‐Hydroxypyrazoles Initiated by Copper(I)‐Catalyzed Carboxylation of Terminal Alkynes.

Silver tungstate: a single-component bifunctional catalyst for carboxylation of terminal alkynes with CO2 in ambient conditions

The ligand-free carboxylation of various terminal alkynes promoted by Ag2WO4 was conducted at room temperature and verified with 13CO2.

1,1'-Bis(di-tert-butylphosphino)ferrocene copper(I) complex catalyzed C-H activation and carboxylation of terminal alkynes.

Four copper(i) complexes, [CuBr(dtbpf)] (1), [CuI(dtbpf)] (2), [Cu4(μ2-I)2(μ3-I)2(μ-dtbpf)2] (3) and [Cu6(μ3-I)6(μ-dtbpf)2]·2CH3CN (4), were prepared using CuX (X = Br, I) and 1,1'-bis(di-tert-butylphosphino)ferrocene (dtbpf). These complexes have been characterized by elemental analyses, IR, (1)H and (31)P NMR, ESI-MS and electronic absorption spectroscopy. Molecular structures of the complexes 2 and 4 were determined crystallographically. Complex 2 is the first monomeric isolated Cu(i) complex of dtbpf with the largest P-Cu-P bite angle (120.070(19)°) to date. Complex 4 shows a centrosymmetrical dimeric unit with two [Cu3(μ3-I)3] motifs bridged by two bidentate dtbpf ligands in the κ(1)-manner. Each [Cu3(μ3-I)3] motif unites to form a pyramid with one copper atom at the apex and one of the triangular faces capped by an iodine atom. All the complexes were found to be efficient catalysts for the conversion of terminal alkynes into propiolic acids with CO2. Owing to the excellent catalytic activity, the reactions proceeded at atmospheric pressure and ambient temperature (25 °C). The catalytic products were obtained in moderate to good yields (80-96%) by using complex loading to 2 mol%. To the best of our knowledge, this is the first example of an active ferrocenyl diphosphine Cu(i) catalyst for the carboxylation of terminal alkynes with CO2.

Carboxylation of terminal alkynes with CO2 catalyzed by bis(amidate) rare-earth metal amides

Three novel bis(amidate) rare-earth metal amides were prepared and characterized. Treatment of CO2 with terminal alkynes obtained propiolic acids in high to excellent yields using the highest reactive Nd-based catalyst at ambient pressure.

ChemInform Abstract: DBU and Copper(I) Mediated Carboxylation of Terminal Alkynes Using Supercritical CO2 as a Reactant and Solvent.

AbstractOptimized conditions are developed for the DBU mediated carboxylation of terminal alkynes with supercritical CO2 to form the corresponding propiolic acids.

Computational characterization of the mechanism for coinage-metal-catalyzed carboxylation of terminal alkynes.

Several experimentally reported copper-, silver-, and gold-catalyzed carboxylation processes of terminal alkynes are studied with DFT methods to find out the mechanism ruling these transformations. The computational results indicate that the reaction follows a very similar pathway for all three metals: the crucial step involves the electrophilic attack of an unactivated carbon dioxide unit on a metal-σ-acetylide complex. The calculations lead to the proposal of additional silver and gold catalytic systems that could perform this reaction at mild temperatures.

Nickel-catalyzed double carboxylation of alkynes employing carbon dioxide.

The nickel-catalyzed double carboxylation of internal alkynes employing carbon dioxide (CO2) has been developed. The reactions proceed under CO2 (1 atm) at room temperature in the presence of a nickel catalyst, Zn powder as a reducing reagent, and MgBr2 as an indispensable additive. Various internal alkynes could be converted to the corresponding maleic anhydrides in good to high yields. DFT calculations disclosed the indispensable role of MgBr2 in the second CO2 insertion.

Consecutive Three‐Component Synthesis of 2,6‐Disubstituted Pyrimid‐4(3H)‐ones and 1,5‐Disubstituted 3‐Hydroxypyrazoles Initiated by Copper(I)‐Catalyzed Carboxylation of Terminal Alkynes

AbstractA copper(I)‐catalyzed carboxylation of terminal alkynes followed trapping of the carboxylate with methyl iodide provides a straightforward access to 3‐substituted methyl propiolates that can be reacted in the same reaction vessel in a consecutive fashion to give 2,6‐disubstituted pyrimid‐4(3H)‐ones and 1,5‐disubstituted 3‐hydroxypyrazoles in moderate to good yields. The Cu(I)‐catalyzed carboxylation with carbon dioxide as C1 source therefore provides an environmentally benign entry to three‐carbon building blocks in heterocyclic synthesis.magnified image

DFT Studies on the Silver-Catalyzed Carboxylation of Terminal Alkynes with CO2: An Insight into the Catalytically Active Species

DFT calculations on the Ag-catalyzed carboxylation of phenyl acetylene with CO2 indicate that the true catalytically active species is a CsCO3–-coordinated Ag complex rather than neutral PhC≡CAg conventionally considered for such a process. The energy barrier for the insertion of CO2 into the C–Ag bond of PhC≡CAg (28.8 kcal/mol) is higher than that of PhC≡CAgI– and PhC≡CAgCsCO3– anions (19.0 and 23.6 kcal/mol, respectively). Such an anion as a key intermediate is the predominant feature of the carboxylation process. The electronic effect plays a crucial role in stabilizing such transition states. In addition, the presence of an organic ligand slightly hampers generation of the active species and, therefore, reduced the yield of the final carboxylation product, which was observed experimentally.

DBU and copper(I) mediated carboxylation of terminal alkynes using supercritical CO2 as a reactant and solvent

An organic solvent free, DBU (1,8-Diazabicyclo[5.4.0]undec-7-ene)-mediated and copper(I)-catalyzed CH activating carboxylation of terminal alkynes in supercritical CO2 (ScCO2) was developed in this work. Terminal alkynes react with ScCO2 in the presence of CuI/DBU and produce the corresponding functionalized propiolic acids in excellent yields. Under the optimized conditions, carbon dioxide can act as both reactant and solvent for the reaction. DBU serves as a ligand of copper catalyst, nucleophile, and base during the reaction. DBU alone can also mediate the direct CH carboxylation in the absence of transit metal catalyst. But the reaction requires a higher reaction temperature and pressure to obtain desired yields.

Metalloenzyme-Mimicking Supramolecular Catalyst for Highly Active and Selective Intramolecular Alkyne Carboxylation

Creation of synthetic catalysts with enzyme-like behavior is challenging despite strong interest in such systems. Extraction of tetrachloroaurate into the hydrophilic core of an interfacially cross-linked reverse micelle (ICRM) produced an artificial "metalloenzyme" with highly unusual catalytic properties. The ICRM pulled the substrate toward the catalytic metal, which converted it efficiently to the product that was rapidly ejected. These features enabled greatly reduced catalyst loading (30-100 times lower than typical levels used in literature examples), constant high reaction rate throughout the course of the reaction, lack of the hydrolyzed side product, and substrate selectivity unobserved in conventional gold catalysts.

ChemInform Abstract: Direct Carboxylative Reactions for the Transformation of Carbon Dioxide into Carboxylic Acids and Derivatives

AbstractReview: 77 refs.