Carboxylation Of Terminal Alkynes Research Articles

Differential Activation of Alkynes between Capped and Naked Ag Nanoclusters Anchored by Highly-Open Mesoporous CeO2 for Two Coupling Reactions with CO2.

The cyclization of 3-hydroxy alkynes and the carboxylation of terminal alkynes both with CO2 are two attractive strategies to simultaneously reduce CO2 emission and produce value-added chemicals. Herein, the differential activation of alkynes over atomically precise Ag nanoclusters (NCs) supported on Metal-organic framework-derivedhighly-open mesoporous CeO2 (HM-CeO2) by reserving or removing their surface captopril ligands is reported. The ligand-capped Ag NCs possess electron-rich Ag atoms as efficient π-activation catalytic sites in cyclization reactions, while the naked Ag NCs possess partial positive-charged Ag atoms as perfect σ-activation catalytic sites in carboxylation reactions. Impressively, via coupling with HM-CeO2 featuring abundant basic sites and quick mass transfer, the ligand-capped Ag NCs afford 97.9% yield of 4,4-dimethyl-5-methylidene-1,3-dioxolan-2-one for the cyclization of 2-methyl-3-butyn-2-ol with CO2, which is 4.5 times that of the naked Ag NCs (21.7%), while the naked Ag NCs achieve 98.5% yield of n-butyl 2-alkynoate for the carboxylation of phenylacetylene with CO2, which is 15.6 times that of ligand-capped Ag NCs (6.3%). Density functional theory calculations reveal the ligand-capped Ag NCs can effectively activate alkynyl carbonate ions for the intramolecular ring closing in cyclization reaction, while the naked Ag NCs are highly affiliative in stabilizing terminal alkynyl anions for the insertion of CO2 in carboxylation reaction.

Green carboxylation of CO2 triggered by well-dispersed silver nanoparticles immobilized by melamine-based porous organic polymers

CO2 fixation via directly formation of C-C bonds to obtain carboxylation compound is an essential reaction in industry. Creating efficient, inexpensive and industrially valuable key catalysts have always been a desire, but also an urgent challenge. Here, we synthesized a kind of melamine-based porous organic polymers (POPs) evenly loaded Ag Nanoparticles (Ag NPs/Melamine-based POPs) by the gas bubbling-assisted membrane reduction (GBMR) approach. The melamine-based POPs were used as good nitrogen-rich supports for loading and dispersing Ag nanoparticles. Ag NPs/ melamine-based POPs exhibited good CO2 absorption capacity (2.1 mmol/g, 273 K and 0.1 MPa) and the excellent activity was up to 93% towards the carboxylation of terminal alkynes with CO2 under mild reaction conditions (323 K, 0.1 MPa). And the TOF is 2.23 h−1. Specially, this is very few report of heterogeneously catalyzed directly formation of carboxylation compound only applying terminal alkynes with CO2 under low temperature and atmospheric pressure. The mechanistic study revealed that the well-dispersed Ag active species promoted highly efficient and green conversion of CO2. Moreover, the catalyst was easily recovered and could be reused at least six times with retention of high catalytic activity.

Covalent Organic Framework Catalysts for Carboxylation of Terminal Alkynes

Covalent Organic Framework Catalysts for Carboxylation of Terminal Alkynes

Carbon-11 carboxylation of terminal alkynes with [11 C]CO2.

A copper-catalysed radiosynthesis of carbon-11 radiolabelled carboxylic acids was developed by reacting terminal alkynes and cyclotron-produced carbon-11 carbon dioxide ([11 C]CO2 ) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). A small library of 11 C-labelled propiolic acid derivatives were obtained with a total synthesis time of 15 min from end of bombardment (EOB) with a (non-isolated) radiochemical yield ranging from 7% to 28%.

Copper(I)-modified covalent organic framework for CO2 insertion to terminal alkynes

The carboxylation of terminal alkynes with CO2 is an attractive route for CO2 fixation and conversion, and various homogeneous Cu(I) catalysts have been explored for the reaction. However, it is still a challenge to develop efficient heterogeneous catalysts for the conversion under mild conditions. Considering that covalent organic frameworks (COFs) are emerging as versatile platforms for the design of functional materials, we developed a TpBpy-supported Cu(I) catalyst, where TpBpy is a stable imine-type porous COF furnished with rich N,N- and N,O-chelating sites for Cu(I) immobilization. The hybrid material can efficiently catalyze the conversion of CO2 and terminal alkynes to propiolic acids under relatively mild conditions (1 atm CO2, 60 ℃). The catalytic activity arises from the synergy between the organic framework of TpBpy and the Cu(I) sites. Not merely serving as a porous support to afford isolated and accessible Cu(I) sites, the organic framework itself has its own catalytic activity through the polar and basic N and O functional sites, which could activate the C–H bond and facilitate CO2 absorption. In addition, the framework also serves as a giant ligand to shift the reversible Cu(I)-catalyzed process in favor of carboxylation. The catalyst shows somewhat reduced activity after reused for three cycles owing to the oxidation of Cu(I) to Cu(II), but it can be easily regenerated by treating with KI.

Recent advances in catalytic conversion of carbon dioxide to propiolic acids over coinage-metal-based catalysts

The recent advances of the coupling from terminal alkynes with CO2 as a green carboxylative reagent over the coinage-metal-based catalyst systems are reviewed. The conversion of inexpensive, available C 1 feedstock of carbon dioxide (CO 2 ) into value-added fine chemicals via homogeneous or heterogeneous catalysis has attracted great recent interest. Coinage-metal-based (Cu, Ag, and Au) catalysis has emerged as a synthetic strategy for a wide range of organic chemical reactions in past decades. In coinage-metal-catalyzed carboxylation, CO 2 is adopted as a carboxylation reagent, while coinage-metal salts, complexes, and nanoparticles (NPs) serve as a Lewis acid catalyst to activate unsaturated chemicals, particularly alkynes. This mini-review focuses on the recent advances of coinage-metal-catalyzed carboxylation of terminal alkynes with CO 2 . Other respects, such as the role of bases, the influence of trace water, and solvent effects are also highlighted.

Synthesis of Esters and Lactones by Carboxylation of Terminal Alkynes on Ag Nanoparticle-Doped MgO

Key words magnesium oxide - silver catalysis - alkynes - carboxylation - esters - lactones

Recent Advances in Decarboxylative Reactions of Alkynoic Acids

Alkynoic acids have been widely employed as alkyne and alkene sources in decarboxylative reactions. Alkynoic acid coupling leads to the formation of direct coupling products and cyclized products through sequential reactions. Moreover, homocoupling and multicomponent reactions have been developed. The decarboxylative addition of alkynoic acids generates the corresponding alkene products. A number of synthetic methods are utilized for the preparation of arylpropynoic acids including the Sonogashira coupling and the carboxylation of terminal alkynes. Recently, the use of decarboxylative halogenations has also been reported. This review covers decarboxylative reactions of alkynoic acids reported between 2013 and 2019; further, it is divided into several sections according to the type of reaction.1 Introduction2 Direct Coupling3 Sequential Reactions4 Homocoupling5 Multicomponent Reactions6 Addition7 Halogenations8 Synthesis of Alkynoic Acids9 Conclusion

Cu-MOF-Catalyzed Carboxylation of Alkynes and Epoxides

The catalytic activity of copper-containing heterogeneous catalysts, in particular metal-organic frameworks, zeolites, and alumina-supported nanoparticles, in the carboxylation of terminal alkynes and oxiranes has been evaluated. Temperature dependences of these reactions have been studied.

Response to Commentary by T. Mita on Transition Metal-Catalyzed Carboxylation of Terminal Alkynes with CO2

Response to Commentary by T. Mita on Transition Metal-Catalyzed Carboxylation of Terminal Alkynes with CO2

Core-shell metal-organic frameworks and metal functionalization to access highest efficiency in catalytic carboxylation

A core-shell metal-organic frameworks (MOF@MOF) based on the Zr-MOFs assembly from core-structure UiO-66 combined with shell-structure UiO-67-BPY were explored. The synthesized materials were characterized via XRD, FTIR, SEM, TEM, and surface area analysis, etc. indicating the presence of a core-shell structure of UiO-66@UiO-67-BPY. Furthermore, incorporation of the bipyridinic (BPY) group in the linker used to construct the shell layer (UiO-67-BPY) could coordinate with active metal species and thus create an advantage for site-selective metal incorporation in the core-shell structure. Silver (Ag) was selected for the selective metal incorporation and an excellent Ag-dispersion via coordination with the bipyridinic groups in the UiO-67-BPY layer of the core-shell material was obtained. The synthesized material (UiO-66@UiO-67-BPY-Ag) was successfully applied as a heterogeneous catalyst for the CO2 fixation via carboxylation of terminal alkynes. The catalytic material showed excellent yields using at a low Ag-loading under mild reaction condition (50 °C, 1 bar). Moreover, the catalyst can be recycled for at least 5 times maintaining a stable catalytic performance. Interestingly, the high catalytic activity of the synthesized material demonstrated clearly the beneficial advantage of the metalated core-shell structure over the reported routes to synthesize silver catalysts such as encapsulated Ag nanoparticles (AgNP@MOF) or Ag-bidentately coordinated on traditional MOFs applying the same reaction model.

A facile synthesis strategy to couple porous nanocubes of CeO2 with Ag nanoparticles: an excellent catalyst with enhanced reactivity for the ‘click reaction’ and carboxylation of terminal alkynes

CeO2–Ag nanocomposite was synthesized by modifying the surface of CeO2 with DMP and its catalytic activity was shown for click reaction and carboxylation of terminal alkynes.

Carboxylation of Terminal Alkynes with Carbon Dioxide Catalyzed by an In Situ Ag2O/N‐Heterocyclic Carbene Precursor System

AbstractA carboxylation of terminal alkynes with carbon dioxide (CO2) at ambient conditions was developed in situ using a series of N‐heterocyclic carbene (NHC) precursors and Ag2O. The unique structure of NHCs largely increases the solubility of active Ag species and meanwhile activates CO2 by forming the NHC–CO2 adduct. This novel catalytic system demonstrated quite low Ag loading, very high activities, wide substrate generality and excellent tolerance for a variety of functionalities. In addition, avoiding cumbersome synthesis procedures, processing, and reserving of the photosensitive Ag complex, this system could be stored and operated as straightforward as the inorganic Ag salt catalysts.

Inserting CO2 into Terminal Alkynes via Bis-(NHC)-Metal Complexes

The direct interaction between CO2 and terminal alkynes in the presence of bis-(NHC)-metal catalysts at ambient conditions was studied. Two Cu and Ag-based bis-N-heterocyclic carbene Transition Metal catalysts were synthesized. The (NHC)2-Ag complex showed a better catalytic performance towards the carboxylation of terminal alkynes in comparison with the copper analogue even for the conversion of acetylene gas. The optimized conditions for the carboxylation are: the use of Cs2CO3 as additive, one atmosphere CO2 and room temperature using 1% mol catalyst. Mechanistic insight into the reaction mechanism is obtained by means of state-of-the-art first principles calculations.

Silver nanoparticles embedded over porous metal organic frameworks for carbon dioxide fixation via carboxylation of terminal alkynes at ambient pressure

Ag nanoparticles (NPs) has been supported over a porous Co(II)-salicylate metal-organic framework to yield a new nanocatalyst AgNPs/Co-MOF and it has been thoroughly characterized by powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy dispersive X-ray spectrometry (EDX), high-resolution transmission electron microscopy (HR-TEM), UV–vis diffuse reflection spectroscopy (DRS) and N2 adsorption/desorption analysis. The AgNPs/Co-MOF material showed high catalytic activity in the carboxylation of terminal alkynes via CO2 fixation reaction to yield alkynyl carboxylic acids under very mild conditions. Due to the presence of highly reactive AgNPs bound at the porous MOF framework the reaction proceeded smoothly at 1atm CO2 pressure. Moreover, the catalyst is very convenient to handle and it can be reused for several reaction cycles without appreciable loss of catalytic activity in this CO2 fixation reaction, which suggested a promising future of AgNPs/Co-MOF nanocatalyst.

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

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

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.

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.

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

AbstractReview: 77 refs.