- Bulky 1,1′-bisphosphanoferrocenes and their coordination behaviour towards Cu(i)
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Two bulky mesityl substituted dppf-analogues Fe(C5H4PMes2)2 (Mes = 2,4,6-Me3C6H2, 1) and Fe(C5H4PMes2)(C5H4PPh2) (Mes = 2,4,6-Me3C6H2, Ph = C6H5, 3) have been prepared and their properties as donor ligands have been explored using heteronuclear NMR spectroscopy and in particular via1JP-Se coupling, cyclic voltammetry and DFT calculations. Based on the results obtained, a series of mono- and dinuclear Cu(i) complexes have been prepared with these new diphosphane ligands using Br-, I-, and BF4- as counter anions. For the very bulky ligand 1 rare and unprecedented double bridging complexation modes have been observed containing two non-planar Cu2Br2 units, while for the other dinuclear complexes planar Cu2Br2 units have been found. The Cu(i) complexes of 1 and 3 were then used as catalysts for CO2-fixation reaction with terminal alkynes, and complexes with ligand 3 were found to be more efficient than those with 1. DFT calculations performed on compounds 1, 3 and their Cu(i) complexes were able to verify the trend of these catalytic reactions.
- Bruhn, Clemens,Buzsáki, Daniel,Dey, Subhayan,Kelemen, Zsolt,Pietschnig, Rudolf
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Read Online
- Carboxylation of phenylacetylene by carbon dioxide on heterogeneous Ag-containing catalysts
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A possibility of using heterogeneous catalysts with a low silver content for the direct carb-oxylation of phenylacetylene by carbon dioxide was demonstrated. A comparative study of the efficiency of the heterogeneous Ag-containing catalysts on different oxide supports (F-γ-Al2O3, γ-Al2O3, TiO2, SiO2) revealed that phenylpropiolic acid in the highest yield (62.1%) was achieved on the 0.5% Ag/F-Al2O3 catalysts.
- Finashina,Kustov,Tkachenko,Krasovskiy,Formenova,Beletskaya
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Read Online
- Method for synthesizing acetylenic acid by using terminal alkyne and carbon dioxide
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The invention belongs to the field of organic synthesis, and particularly relates to a method for synthesizing acetylenic acid by using terminal alkyne and carbon dioxide. The method comprises the experimental steps that alkyne, alkali and a solvent are added into a reaction tube, the alkyne serves as a raw material, the alkali and the solvent provide a strong alkaline environment, CO2 is introduced into a reaction container to form a carbon dioxide atmosphere, heating and stirring reaction are carried out, after the reaction is finished, cooling is carried out to the room temperature, extraction and liquid separation are carried out, a water layer is acidified, then separation and purification are further carried out, and the acetylenic acid compound is obtained. The method is carried out under the conditions of low temperature and normal pressure, does not need to add a metal catalyst, is single in product and convenient to separate, good in substrate applicability and safe and simple to operate, and has potential industrial application prospects and good economic benefits.
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Paragraph 0052-0056; 0055-0057; 0058-0060; 0061-0063; ...
(2021/07/24)
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- Pre-carbonized nitrogen-rich polytriazines for the controlled growth of silver nanoparticles: Catalysts for enhanced CO2chemical conversion at atmospheric pressure
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High catalytic activity and sufficient durability are two unavoidable key indices of an efficient heterogeneous catalyst for the direct carboxylation of terminal alkynes with CO2 conversion. Nitrogen-rich covalent triazine frameworks (CTFs) are promising substrates, while random distribution of some residual -NH2 groups brings challenges to the controlled growth of catalytic species. Here, we adopt a pre-carbonization protocol, annealing below the carbonization temperature, to eliminate the random -NH2 groups in CTFs and meanwhile to promote polycondensation degree under the premise of maintaining the pore structure. Benefiting from the improved condensation and orderly N atoms, p-CTF-250, for which CTFs are annealed at 250 °C, exhibits improved CO2 adsorption capacity and the ability to control the growth of Ag NPs. Mono-dispersed Ag NPs are generated controllably and entrapped to form Ag@p-CTF-250 catalysts. These Ag@p-CTF-250 catalysts were employed in the direct carboxylation of various terminal alkynes with CO2 under mild conditions (50 °C, 1 atm) and showed excellent catalytic activity. In addition, these catalysts have robust recyclability and can be used for at least 5 catalytic runs while retaining yield above 90%. CO2 conversion proceeds well under the synergistic effect between the high CO2 capture capability and the uniform tiny Ag NPs in Ag@p-CTF-250 "nanoreactors". The results represent an efficient strategy for controlling the growth of metallic nanoparticles in porous organic polymer substrates containing disordered heteroatoms.
- Liu, Jian,Zhang, Xiaoyi,Wen, Bingyan,Li, Yipei,Wu, Jingjing,Wang, Zhipeng,Wu, Ting,Zhao, Rusong,Yang, Shenghong
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p. 3119 - 3127
(2021/05/25)
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- Copper(I)-modified covalent organic framework for CO2 insertion to terminal alkynes
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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.
- Bu, Ran,Zhang, Lin,Gao, Lu-Lu,Sun, Weng-Jie,Yang, Shuai-Liang,Gao, En-Qing
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- Organocatalytic Strategy for the Fixation of CO2via Carboxylation of Terminal Alkynes
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An organocatalytic strategy for the direct carboxylation of terminal alkynes with CO2 has been developed. The combined use of a bifunctional organocatalyst and Cs2CO3 resulted in a robust catalytic system for the preparation of a range of propiolic acid derivatives in high yields with broad substrate scope using CO2 at atmospheric pressure under mild temperatures (60 °C). This work has demonstrated that this organocatalytic method offers a competitive alternative to metal catalysis for the carboxylation of terminal alkynes and CO2. In addition, this protocol was suitable for the three-component carboxylation of terminal alkynes, alkyl halides, and CO2.
- Shi, Jun-Bin,Bu, Qingqing,Liu, Bin-Yuan,Dai, Bin,Liu, Ning
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supporting information
p. 1850 - 1860
(2021/01/14)
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- N-Heterocyclic carbene-nitrogen molybdenum catalysts for utilization of CO2
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Three new N-heterocyclic carbene-nitrogen molybdenum complex was synthesized, and its catalytic activity was evaluated in the cycloaddition of epoxides with CO2. The molybdenum complex combined with tetrabutyl ammonium iodide (TBAI) resulted in a catalytic system for efficient conversion of a wide range of terminal and internal epoxides under 80 °C and 5–7 bar pressure for CO2. The cooperative catalysis mechanism between molybdenum complex and TBAI was elucidated, in which molybdenum complex was used as Lewis acid, and TBAI was employed as nucleophilic reagent. In addition, the NHC-Mo catalytic system was also successfully applied for the direct carboxylation of terminal alkynes with CO2.
- Chen, Fei,Tao, Sheng,Liu, Ning,Dai, Bin
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- An efficient Ag/MIL-100(Fe) catalyst for photothermal conversion of CO2 at ambient temperature
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The conversion of CO2 under mild condition is of great importance because these reactions involving CO2 can not only produce value-added chemicals from abundant and inexpensive CO2 feedstock but also close the carbon cycle. However, the chemical inertness of CO2 requires the development of high-performance catalysts. Herein, Ag nanoparticles/MIL-100(Fe) composites were synthesized by simple impregnation-reduction method and employed as catalysts for the photothermal carboxylation of terminal alkynes with CO2. MIL-100(Fe) could stabilize Ag nanoparticles and prevent them from aggregation during catalytic process. Taking the advantages of photothermal effects and catalytic activities of both Ag nanoparticles and MIL-100(Fe), various aromatic alkynes could be converted to corresponding carboxylic acid products (86%–92% yields) with 1 atm CO2 at room temperature under visible light irradiation when using Ag nanoparticles/MIL-100(Fe) as photothermal catalysts. The catalysts also showed good recyclability with almost no loss of catalytic activity for three consecutive runs. More importantly, the catalytic performance of Ag nanoparticles/MIL-100(Fe) under visible light irradiation at room temperature was comparable to that upon heating, showing that the light source could replace conventional heating method to drive the reaction. This work provided a promising strategy of utilizing solar energy for achieving efficient CO2 conversion to value-added chemicals under mild condition.
- Jing, Peng,Wu, Boyuan,Han, Zongsu,Shi, Wei,Cheng, Peng
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supporting information
p. 3505 - 3508
(2021/05/04)
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- Microwave-assisted fabrication of a mixed-ligand [Cu4(μ3-OH)2]-cluster-based metal–organic framework with coordinatively unsaturated metal sites for carboxylation of terminal alkynes with carbon dioxide
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The development of efficient and stable metal–organic framework (MOF) catalysts with coordinatively unsaturated metal sites for modern organic synthesis is greatly important. Herein, a robust [Cu4(μ3-OH)2]-cluster-based MOF (Cu-MOF) with a mixed-ligand system was successfully fabricated by a microwave-assisted method under mild conditions. The as-prepared Cu-MOF catalyst possessing unsaturated Cu (II) sites exhibited excellent catalytic activity toward the direct carboxylation of 1-ethynylbenzene with CO2, and various propiolic acid derivatives were synthesized in moderate to good yields under optimized reaction conditions. Furthermore, the catalyst remained stable and could be easily recycled for five sequential runs without incredible decrease in catalytic efficiency.
- Wang, Wen-Jing,Sun, Zhong-Hua,Chen, Sheng-Chun,Qian, Jun-Feng,He, Ming-Yang,Chen, Qun
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- Schiff-base molecules and COFs as metal-free catalysts or silver supports for carboxylation of alkynes with CO2
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Carboxylation of terminal alkynes with CO2 to produce propiolic acids is an atom economical and high-value route for CO2 fixation and utilization, but the conversion under mild conditions needs transition metal catalysts. In this article, we demonstrated for the first time the transition-metal-free organocatalysts for the reaction. The efficient catalysts are Schiff bases derived from 1,3,5-triformylphloroglucinol (Tp), either homogeneous (discrete molecules) or heterogeneous (covalent organic frameworks, COFs). The key catalytic sites are phenoxo and imine groups, which activate CO2 through phenoxo-CO2 complexation and also activate the C(sp)-H bond through bifurcate C-H?Nimine and C-H?Ophenoxo hydrogen bonds. The 2,2′-bipyridyl sites in the COF also contribute to the catalytic performance. The COF catalyst is less active than the molecular one but has the advantages of heterogeneous catalysis. Higher performance was also demonstrated by combining silver nanoparticles (AgNPs) with the intrinsically catalytic COF. This work opens up the potential of developing transition-metal-free catalysts for the CO2 conversion reaction and demonstrates the new prospects of COFs as tailorable platforms for heterogeneous catalysis.
- Bu, Ran,Gao, En-Qing,Liu, Xiao-Yan,Mu, Peng-Fei,Zhang, Lin
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supporting information
p. 7620 - 7629
(2021/10/12)
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- Access to Triazolopiperidine Derivatives via Copper(I)-Catalyzed [3+2] Cycloaddition/Alkenyl C?N Coupling Tandem Reactions
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A copper-catalyzed [3+2] cylcoaddition/ alkenyl C?N coupling tandem reaction was demonstrated. It provided a method for the formation of triazolopiperidine skeletons. (Figure presented.).
- Xiao, Guorong,Wu, Kaifu,Zhou, Wei,Cai, Qian
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supporting information
p. 4988 - 4991
(2021/10/14)
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- CO2-Folded Single-Chain Nanoparticles as Recyclable, Improved Carboxylase Mimics
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Emulating the function of natural carboxylases to convert CO2 under atmospheric condition is a great challenge. Herein we report a class of CO2-folded single-chain nanoparticles (SCNPs) that can function as recyclable, function-intensified carboxylase mimics. Lewis pair polymers containing bulky Lewis acidic and basic groups as the precursor, can bind CO2 to drive an intramolecular folding into SCNPs, in which CO2 as the folded nodes can form gas-bridged bonds. Such bridging linkages highly activate CO2, which endows the SCNPs with extraordinary catalytic ability that can not only catalyze CO2-insertion of C(sp3)-H for imitating the natural enzyme's function, it can also act on non-natural carboxylation pathways for C(sp2 and sp)-H substrates. The nanocatalysts are of highly catalytic efficiency and recyclability, and can work at room temperature and near ambient CO2 condition, inspiring a new approach to sustainable C1 utilization.
- Chen, Liang,Yan, Qiang,Zeng, Rongjin
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supporting information
p. 18418 - 18422
(2020/08/21)
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- Activated charcoal as an effective additive for alkaline and acidic hydrolysis of esters in water
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Activated charcoal largely enhanced the rates of the alkaline hydrolysis of methyl, ethyl, and n-propyl esters in aqueous 1.5 M NaOH solution to give the corresponding carboxylic acids in excellent yields. The acidic hydrolysis of methyl, ethyl, and n-propyl esters in aqueous 3 M H2SO4 solution was accelerated by the addition of activated charcoal to afford the corresponding carboxylic acids in good yields.
- Rohand, Taoufik,Tanemura, Kiyoshi
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supporting information
(2020/10/08)
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- Design and Remarkable Efficiency of the Robust Sandwich Cluster Composite Nanocatalysts ZIF-8@Au25@ZIF-67
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Heterogeneous catalysts with precise surface and interface structures are of great interest to decipher the structure-property relationships and maintain remarkable stability while achieving high activity. Here, we report the design and fabrication of the new sandwich composites ZIF-8@Au25@ZIF-67[tkn] and ZIF-8@Au25@ZIF-8[tkn] [tkn = thickness of shell] by coordination-assisted self-assembly with well-defined structures and interfaces. The composites ZIF-8@Au25@ZIF-67 efficiently catalyzed both 4-nitrophenol reduction and terminal alkyne carboxylation with CO2 under ambient conditions with remarkably improved activity and stability, compared to the simple components Au25/ZIF-8 and Au25@ZIF-8, highlighting the highly useful function of the ultrathin shell. In addition, the performances of these composite sandwich catalysts are conveniently regulated by the shell thickness. This concept and achievements should open a new avenue to the targeted design of well-defined nanocatalysts with enhanced activities and stabilities for challenging reactions.
- Yun, Yapei,Sheng, Hongting,Bao, Kang,Xu, Li,Zhang, Yu,Astruc, Didier,Zhu, Manzhou
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supporting information
p. 4126 - 4130
(2020/03/05)
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- Synthesis and Catalytic Properties of Metal- N-Heterocyclic-Carbene-Decorated Covalent Organic Framework
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We demonstrate herein that the N-heterocyclic-carbene (NHC)-metal complex (NHC-M)-involved covalent organic framework (COF) can be prepared by the direct polymerization of the NHC-M monomer with its counterpart under solvothermal conditions. The NHC-M-COF with different counterions is readily achieved via solid-state anion exchange. The obtained NHC-AuX-COF (X = Cl- and SbF6-) can be a highly active reusable catalyst to separately promote the carboxylation of the terminal alkyne with CO2 and alkyne hydration under mild conditions.
- Dong, Ying,Dong, Yu-Bin,Kan, Jing-Lan,Li, Yue,Wu, Xiaowei
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supporting information
p. 7363 - 7368
(2020/10/12)
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- Silver Nanoparticles Architectured HMP as a Recyclable Catalyst for Tetramic Acid and Propiolic Acid Synthesis through CO2 Capture at Atmospheric Pressure
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The recent advancement on the tailored synthesis of hypercrosslinked microporous polymer (HMP-2) has assembled significant concentration by the virtue of its adjustable porosity, operative design and absolutely ordering structure. This perfectly structured Ag NPs supported carbocatalyst (Ag-HMP-2) has been synthesized by Friedel-Crafts alkylation between 4,4′-Bis(bromomethyl)-1,1′-biphenyl and carbazole over anhydrous iron(III)chloride catalysis followed by the appending of the silver nanoparticles (Ag NPs) onto the material. The silver nanoparticle was decorated over the HMP-2 to prepare the corresponding catalyst (Ag-HMP-2). The characterization of the newly produced material has been conducted by N2 adsorption/desorption studies, XPS, FE-SEM, transmission electron microscopy (TEM) and Powder X-ray diffraction (PXRD) methods. This microporous catalyst has spectacular activities for the production of tetramic acids from various types of propargylic amine derivatives at 60 °C under atmospheric carbon dioxide pressure. Parallel attempt on fixation of CO2 was executed over terminal alkynes to synthesize propiolic acids under 1 atm pressure. The catalyst (Ag-HMP-2) exhibited sufficient recycling ability for the generation of tetramic acids and propiolic acids up to five catalytic runs without reduction in its catalytic activity.
- Ghosh, Swarbhanu,Ghosh, Aniruddha,Riyajuddin, Sk,Sarkar, Somnath,Chowdhury, Arpita Hazra,Ghosh, Kaushik,Islam, Sk. Manirul
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p. 1055 - 1067
(2020/01/21)
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- Development of magnesium oxide-silver hybrid nanocatalysts for synergistic carbon dioxide activation to afford esters and heterocycles at ambient pressure
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Multi-metallic hybrid nanocatalysts consisting of a porous metal oxide host and metal satellite guests serve as a scaffold for multi-step transformations of divergent and energy-challenging substrates. Here we have developed a 3D porous MgO framework (Lewis basic host) with Ag0 nanoparticles (noble metal guest) for ambient pressure activation and insertion of CO2 into unsaturated alkyne substrates. The hybrid MgO@Ag-x (x = 2, 5, 7, 8 at% Ag) catalysts are synthesized by impregnating Ag+ ions in porous MgO cubes followed by reduction using NaBH4. Morphological (SEM, TEM, EDX mapping) and structural (PXRD, XPS) characterization reveal that the micron-sized hybrid cubes derive from self-assembly of ～100 nm (edge length) MgO cubes decorated with ～5 to 25 nm Ag0 NPs. Detailed XPS analysis illustrates Ag0 is present in two forms, 2 into aryl alkynes followed by SN2 coupling with allylic chlorides to afford a wide range of ester and lactone heterocycles in excellent yields (61-93%) and with low E-factor (2.8). The proposed mechanism suggests a CO2 capture and substrate assembly role for 3D porous MgO while Ag0 performs the key activation of alkyne and CO2 insertion steps. The catalyst is recyclable (5×) with no significant loss of product yield. Overall, these results demonstrate viable approaches to hybrid catalyst development for challenging conversions such as CO2 utilization in a green and sustainable manner.
- Gulati, Upasana,Chinna Rajesh,Rawat, Diwan S.,Zaleski, Jeffrey M.
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supporting information
p. 3170 - 3177
(2020/06/18)
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- AgNPs encapsulated by an amine-functionalized polymer nanocatalyst for CO2 fixation as a carboxylic acid and the oxidation of cyclohexane under ambient conditions
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Silver nanoparticles (AgNPs) embedded in a porous polystyrene material (AgNPs@m-PS-PC) were synthesized via the polymerization of polystyrene amine and 2-pyridinecarbaldehyde, followed by the reduction of silver nitrate in methanol. The structure and morphology of this porous material were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy, Fourier-transform infrared, ultraviolet-visible, and atomic absorption spectroscopies, and thermogravimetric analysis. TEM showed that the AgNPs were well dispersed in the polymeric matrix, with dimensions of around 4-9 nm. This nanocatalyst showed activity, particularly for the green synthesis of valuable carboxylic acids by the carboxylation reaction of terminal alkynes with carbon dioxide under atmospheric pressure. Additionally, the catalyst displayed efficient catalytic activity for the oxidation of cyclohexane using hydrogen peroxide as the oxidising agent. The AgNPs@m-PS-PC nanocatalyst could be recycled five times and retained reliable efficiency.
- Salam, Noor,Paul, Priyanka,Ghosh, Swarbhanu,Mandi, Usha,Khan, Aslam,Alam, Seikh Mafiz,Das, Debasis,Manirul Islam, Sk.
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p. 5448 - 5456
(2020/04/17)
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- Exploration of New Biomass-Derived Solvents: Application to Carboxylation Reactions
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A range of hitherto unexplored biomass-derived chemicals have been evaluated as new sustainable solvents for a large variety of CO2-based carboxylation reactions. Known biomass-derived solvents (biosolvents) are also included in the study and the results are compared with commonly used solvents for the reactions. Biosolvents can be efficiently applied in a variety of carboxylation reactions, such as Cu-catalyzed carboxylation of organoboranes and organoboronates, metal-catalyzed hydrocarboxylation, borocarboxylation, and other related reactions. For many of these reactions, the use of biosolvents provides comparable or better yields than the commonly used solvents. The best biosolvents identified are the so far unexplored candidates isosorbide dimethyl ether, acetaldehyde diethyl acetal, rose oxide, and eucalyptol, alongside the known biosolvent 2-methyltetrahydrofuran. This strategy was used for the synthesis of the commercial drugs Fenoprofen and Flurbiprofen.
- Gevorgyan, Ashot,Hopmann, Kathrin H.,Bayer, Annette
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p. 2080 - 2088
(2020/02/20)
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- Cobalt-based catalytic system for the chemical fixation of CO2 under solvent-free conditions
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We have described a novel and efficient method for synthesizing cyclic carbonates with ‘Co (NO3)2 .6H2O/L6’-catalyzed coupling of epoxides and CO2 under solvent-free conditions. We proposed a possible reaction mechanism based on some control experiments. Phenylpropiolic acid could be provided by using the same method.
- Wu, Fengtian,Lin, Yu
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- Compound containing oxazole and triazole diheterocycles, and preparation method and application method thereof
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The invention discloses a compound containing oxazole and triazole diheterocycles. The compound has a structural formula represented by formula (I), and in the formula, R and R are respectivelyand independently selected from any one of alkyl groups, substituted alkyl groups, aryl groups, substituted aryl groups, silyl groups, substituted silyl groups, aliphatic heterocycles and aromatic heterocycles. The compound obtained in the invention has high inhibitory activity on cancer cells, especially human gastric cancer cells MGC803, and provides a new choice for the development and application of gastric cancer treatment drugs. The preparation method is simple to operate, mild in system, low in cost and high in yield, and has great promotion and application values.
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Paragraph 0078; 0097-0099
(2020/05/30)
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- Rh-Catalyzed Asymmetric Hydrogenation of Unsaturated Medium-Ring NH Lactams: Highly Enantioselective Synthesis of N-Unprotected 2,3-Dihydro-1,5-benzothiazepinones
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A straightforward method to prepare 1,5-benzothiazepines was reported. Catalyzed by a Rh/Zhaophos complex, unsaturated cyclic NH lactams with a medium-size ring were hydrogenated smoothly, giving remarkably high enantioselectivities. The sulfur atom in the substrates did not bring an inhibition which was observed with commercially available bisphosphine ligands. This method was successfully applied in the scale-up synthesis of (R)-(-)-thiazesim.
- Yin, Congcong,Yang, Tao,Pan, Yingmin,Wen, Jialin,Zhang, Xumu
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supporting information
p. 920 - 923
(2020/02/04)
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- Gold-catalyzed homo- And cross-annulation of alkynyl carboxylic acids: a facile access to substituted 4-hydroxy 2: H -pyrones and total synthesis of pseudopyronine A
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A Au(i)-catalyzed homo- and cross-annulation reaction of alkynyl carboxylic acids offering 3,6-disubstituted 4-hydroxy 2H-pyrones has been demonstrated. The reaction tolerates various substituted alkynyl carboxylic acids and moderate to good yields of α-pyrone scaffolds have been observed. Later, a gram-scale reaction of the acid and the total synthesis of the natural product pseudopyronine A have been carried out successfully.
- Choudhary, Shivani,Gayyur,Ghosh, Nayan,Saxena, Anchal
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p. 8716 - 8723
(2020/11/17)
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- Visible Light-Catalyzed Decarboxylative Alkynylation of Arenediazonium Salts with Alkynyl Carboxylic Acids: Direct Access to Aryl Alkynes by Organic Photoredox Catalysis
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A convenient method mediated by photoredox catalysis is developed for the direct construction of aryl alkynes. Readily available aromatic diazonium salts have been utilized as the aryl radical source to couple alkynyl carboxylic acids to feature the decarboxylative arylation. A wide range of substrates are amenable to this protocol with broad functional group tolerance, and diversely-functionalized aryl alkynes could be synthesized under mild, neutral and transition metal-free reaction conditions using visible light irradiation. Alongside synthetic sustainability associated with the photocatalytic and transition metal-free operation, another key point of this method is that the organic dye catalyst acts as an excited-state reductant, thus establishing the quenching cycle for radical addition and decarboxylative elimination. (Figure presented.).
- Yang, Liangfeng,Li, Haifeng,Du, Yijun,Cheng, Kai,Qi, Chenze
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p. 5030 - 5041
(2019/11/03)
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- Acetylene and terminal alkyne complexes of copper(i) supported by fluorinated pyrazolates: Syntheses, structures, and transformations
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Trinuclear {μ-[3,5-(CF3)2Pz]Cu}3 reacts with acetylene to produce the 2:1 copper(i) acetylene complex, Cu4(μ-[3,5-(CF3)2Pz])4(μ-HCCH)2. Related Cu4(μ-[4-Br-3,5-(CF3)2Pz])4(μ-HCCH)2 and Cu4(μ-[4-Cl-3,5-(CF3)2Pz])4(μ-HCCH)2 have also been isolated using the corresponding copper(i) pyrazolate and acetylene. The 1:1 adducts Cu2(μ-[3,5-(CF3)2Pz])2(HCCH)2 and Cu2(μ-[4-Br-3,5-(CF3)2Pz])2(HCCH)2 are significantly less stable to the acetylene loss and can be observed in solution at low temperatures under excess acetylene. The X-ray crystal structures of 2:1 and 1:1 complexes, Cu4(μ-[3,5-(CF3)2Pz])4(μ-HCCH)2 and Cu2(μ-[4-Br-3,5-(CF3)2Pz])2(HCCH)2 are reported. Raman data show a reduction in CC stretching frequency by about ～340 and ～163 cm-1 in the 2:1 and 1:1 Cu(i)/acetylene complexes, respectively, from that of the free acetylene. Copper(i) pyrazolate complexes of the terminal alkynes, phenylacetylene, 1,8-nonadiyne, and 1,7-octadiyne are also reported. They form adducts involving one copper atom on each alkyne moiety. The {μ-[3,5-(CF3)2Pz]Cu}3 is also a very versatile and competent catalyst for alkyne transformations as evident from its ability to catalyze the alkyne C(sp)-H bond carboxylation chemistry with CO2, azide-alkyne cycloadditions leading to 1,2,3-triazoles including the use of acetylene itself as a substrate, and thiol addition to phenylacetylene affording vinyl sulfides.
- Parasar, Devaborniny,Ponduru, Tharun T.,Noonikara-Poyil, Anurag,Jayaratna, Naleen B.,Dias, H.V. Rasika
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p. 15782 - 15794
(2019/11/11)
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- Fixation of CO2 as a carboxylic acid precursor by microcrystalline cellulose (MCC) supported Ag NPs: A more efficient, sustainable, biodegradable and eco-friendly catalyst
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Silver nanoparticles supported on microcrystalline cellulose (Ag NPs@MCC), an active catalyst, has been discovered for the direct carbonylation of terminal alkynes with CO2 into carboxylic acid under mild and sustainable reaction conditions. The stabilized Ag NPs show higher distribution with a uniform particle size. The catalyst was characterized by PXRD, SEM, TEM, HR-TEM, EDS, EDX, ICP-AES and XPS analysis. The Ag NPs@MCC material was found to be more efficient, shows excellent dispersion in various solvents and is biodegradable. The solvent effects on carbonylation of terminal alkynes were well studied both experimentally and computationally. Furthermore, the present catalyst can be recycled in up to five catalytic cycles without significant loss of its activity and is also applicable for the gram scale carbonylation of terminal alkynes.
- Shah, Dharmesh J.,Sharma, Anuj S.,Shah, Akshara P.,Sharma, Vinay S.,Athar, Mohd,Soni, Jigar Y.
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supporting information
p. 8669 - 8676
(2019/06/14)
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- Core-shell metal-organic frameworks and metal functionalization to access highest efficiency in catalytic carboxylation
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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.
- Gong, Yanyan,Yuan, Ye,Chen, Cheng,Zhang, Pan,Wang, Jichao,Zhuiykov, Serge,Chaemchuen, Somboon,Verpoort, Francis
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p. 106 - 115
(2019/02/14)
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- Porous Carbon Nitride Frameworks Derived from Covalent Triazine Framework Anchored Ag Nanoparticles for Catalytic CO2 Conversion
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Porous carbon nitride frameworks (PCNFs) with uniform and rich nitrogen dopants and abundant porosity were successfully fabricated through the direct carbonization of the covalent triazine frameworks (CTFs) at different pyrolysis temperatures and used as supports to anchor and stabilize Ag nanoparticles (NPs) for catalytic CO2 conversion. Importantly, the pyrolysis temperature plays a crucial role in the properties of porous carbon nitride frameworks. The material carbonized at 700 °C showed the highest surface area and micro- and mesoporous structure with a certain interlayer distance. Taking advantage of their unique surface characteristics, PCNF-supported Ag NP catalysts (Ag/PCNF-T, T=pyrolysis temperature) were prepared by a simple chemical method. A series of characterizations revealed that Ag NPs are embedded in the porous carbon nitride frameworks and confined to a relatively small size with high dispersion owing to the assistance of the abundant surface groups and porous structures. The as-obtained Ag/PCNF-T catalysts, especially Ag/PCNF-700, showed excellent catalytic activity, selectivity, and stability for the carboxylation of CO2 with terminal alkynes under mild conditions. This can be due to the existence of abundant nitrogen atoms and diverse porosity, which resulted in highly efficient catalytic activity and stability.
- Lan, Xingwang,Li, Yiming,Du, Cheng,She, Tiantian,Li, Qing,Bai, Guoyi
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supporting information
p. 8560 - 8569
(2019/06/08)
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- Carboxylation of terminal alkynes promoted by silver carbamate at ambient pressure
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Transition metal carbamates constitute a class of compounds with unique properties, however their catalytic potential has been sparingly explored so far. The easily available silver N,N-dimethylcarbamate, Ag(O2CNMe2), worked as a catalyst in the carboxylation reaction of terminal alkynes with CO2 at atmospheric pressure. Different reaction parameters (solvent, base, temperature, time and the amount of catalyst) were investigated in order to establish the optimal conditions.
- Bresciani, Giulio,Marchetti, Fabio,Pampaloni, Guido
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p. 10821 - 10825
(2019/07/15)
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- Gold-Catalyzed Post-Ugi Cascade Transformation for the Synthesis of 2-Pyridones
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A gold-catalyzed post-Ugi cascade transformation for the synthesis of 2-pyridones is described. The process involves furan–alkyne cyclization followed by furan ring-opening and cleavage of the isocyanide-originated fragment. The initially formed cis double bond can isomerize into a more stable trans double bond upon prolonged exposure to a strong Br?nsted acid. Thus, the overall strategy provides a viable access towards two types of 2-pyridones.
- Du, Xiaochen,Yu, Jiafeng,Gong, Jing,Zaman, Manzoor,Pereshivko, Olga P.,Peshkov, Vsevolod A.
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supporting information
p. 2502 - 2507
(2019/04/08)
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- Synthesis of 3-Organoselenyl-2H-Coumarins from Propargylic Aryl Ethers via Oxidative Radical Cyclization
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A metal-free oxidative radical cyclization/selenylation of propargylic aryl ethers with diaryl diselenides was developed. This protocol provided an alternative method to synthesize 3-organoselenyl-2H-coumarins via the formation of C?Se bond, C?C bond, and C=O bond in one step. Moreover, a broad range of functional groups (such as halogen, aldehyde, ketone, cyano, and nitro group) were tolerated. (Figure presented.).
- Fang, Jun-Dan,Yan, Xiao-Biao,Zhou, Li,Wang, Yu-Zhao,Liu, Xue-Yuan
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supporting information
p. 1985 - 1990
(2019/03/13)
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- Atom Transfer Oxidative Radical Cascade of Aryl Alkynoates towards 1,1-Dichalcogenide Olefins
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An oxidative trifunctionalization of aryl alkynoates has been devised via the chalcogenide radical triggered intramolecular 1,4-aryl migration/decarboxylation cascade to prepare 1,1-dichalcogenide tetrasubstituted alkenes in high yields (up to 98 %). This operationally simple reaction proceeds under metal-free conditions, can be executed on gram scale, and highlights formal 1,1-difunctionalization of alkynes. Synthetic potential of this protocol was demonstrated through a twofold cascade rearrangement to access highly conjugated tetra-selenylated alkenes along with a cross-dehydrogenative annulation to prepare fluorene derivative.
- Sahoo, Harekrishna,Ramakrishna, Isai,Mandal, Anup,Baidya, Mahiuddin
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supporting information
p. 4549 - 4552
(2019/07/31)
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- Visible-light-mediated selective thiocyanation/ipso-cyclization/oxidation cascade for the synthesis of thiocyanato-containing azaspirotrienediones
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A visible-light-mediated metal-free thiocyanate radical addition/ipso-cyclization/oxidation cascade reaction for the synthesis of thiocyanato-containing azaspirotrienediones from N-phenylpropynamides is described. Cheap and readily available ammonium thiocyanate was used as a precursor to the thiocyanate free radical, which undergoes a radical addition reaction with the alkyne, followed by selective ipso-cyclization and oxidation to afford the dearomatized products. No product of ortho-cyclization was detected. The reaction completes the synthesis of C–S, C–C, and C[dbnd]O bonds in one pot, with abundant and renewable air oxygen as the sole sacrificial reagent and oxygen source.
- Chen, Yuan,Chen, Yu-Jue,Guan, Zhi,He, Yan-Hong
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supporting information
(2019/11/26)
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- A 4-OTBS benzyl-based protective group for carboxylic acids
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Reported herein is a novel 4-OTBS benzyl-based protective group for carboxylic acids. This protective group can be removed in the presence of TBAF or TFA with high efficiency, which makes it compatible with base-sensitive or acid-sensitive substrates. With this protective group, a near-infrared fluorogenic probe for the detection of γ-glutamyltranspeptidase activities was readily prepared.
- Fang, Zhijun,Li, Yuyao,Xie, Hexin
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supporting information
p. 1658 - 1662
(2019/05/29)
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- Sodium Methyl Carbonate as an Effective C1 Synthon. Synthesis of Carboxylic Acids, Benzophenones, and Unsymmetrical Ketones
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Reported is the synthesis of carboxylic acids, symmetrical ketones, and unsymmetrical ketones with selectivity achieved by exploiting the differential reactivity of sodium methyl carbonate with Grignard and organolithium reagents.
- Hurst, Timothy E.,Deichert, Julie A.,Kapeniak, Lucas,Lee, Roland,Harris, Jesse,Jessop, Philip G.,Snieckus, Victor
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supporting information
p. 3882 - 3885
(2019/06/07)
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- Cobalt(III)-Catalyzed Construction of Benzofurans, Benzofuranones and One-Pot Orthogonal C?H Functionalizations to Access Polysubstituted Benzofurans
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Benzofuran and benzofuranone derivatives have been synthesized through exclusive 5-exo-dig intramolecular hydroarylation using the amide-directed, cost-effective, high-valent Cp*CoIII-catalytic system. Challenging one-pot, orthogonal C?H functionalizations using two different electrophiles are also reported to afford polysubstituted benzofurans. Several valuable functional group interconversions along with removal of the amide directing group provide a route to access several diversely functionalized benzofurans. The mechanistic study suggests a reversible cobaltation step is operative here. (Figure presented.).
- Bera, Sourav Sekhar,Debbarma, Suvankar,Jana, Sripati,Maji, Modhu Sudan
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supporting information
p. 2204 - 2210
(2018/06/07)
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- Synthesis and antibacterial evaluation of novel 11-O-aralkylcarbamoyl-3-O-descladinosylclarithromycin derivatives
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A series of novel 11-O-aralkylcarbamoyl-3-O-descladinosylclarithromycin derivatives were designed, synthesized and evaluated for their in vitro antibacterial activity. The results showed that the majority of the target compounds displayed potent activity against erythromycin-susceptible S. pyogenes, erythromycin-resistant S. pneumoniae A22072 expressing the mef gene and S. pneumoniae AB11 expressing the mef and erm genes. Besides, most of the target compounds exhibited moderate activity against erythromycin-susceptible S. aureus ATCC25923 and B. subtilis ATCC9372. In particular, compounds 11a, 11b, 11c, 11e, 11f and 11h were found to exert favorable antibacterial activity against erythromycin-susceptible S. pyogenes with the MIC values of 0.015–0.125 μg/mL. Furthermore, compounds 10e, 11a, 11b and 11c showed superior activity against erythromycin-resistant S. pneumoniae A22072 with the MIC values of 0.25–0.5 μg/mL. Additionally, compound 11c was the most effective against all the erythromycin-resistant S. pneumoniae strains (A22072, B1 and AB11), exhibiting 8-, 8- and 32-fold more potent activity than clarithromycin, respectively.
- Jia, Li,Wang, Yinhu,Wang, Yanxia,Qin, Yinhui,Hu, Chaoyu,Sheng, Juzheng,Ma, Shutao
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p. 2471 - 2476
(2018/06/06)
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- Silver-catalyzed Double Decarboxylative Radical Alkynylation/Annulation of Arylpropiolic Acids with α-keto Acids: Access to Ynones and Flavones under Mild Conditions
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Ynones are privileged building blocks in various organic syntheses of heterocyclic derivatives due to their multifunctional nature, and flavones are an important class of natural products with a wide range of biological activities. We describe the catalytic double decarboxylative alkynylation of arylpropiolic acids with α-keto acids. With Ag(I)/persulfate as the catalysis system, the valuable ynones bearing various substituents could be easily obtained. The introduction of hydroxyl substituent on ortho-site of α-keto acids make this strategy further applicable to the construction of flavone derivatives via heteroannulation in moderate to good yields with a similar silver-catalyzed system. The reactions proceed under relatively mild reaction conditions and tolerate a wide variety of functional groups. Control experiments indicated that both the reactions undergo radical processes. (Figure presented.).
- Meng, Mengting,Wang, Guofang,Yang, Liangfeng,Cheng, Kai,Qi, Chenze
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p. 1218 - 1231
(2018/02/16)
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- Rational encapsulation of atomically precise nanoclusters into metal-organic frameworks by electrostatic attraction for CO2 conversion
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Controlled encapsulation of atomically precise nanoclusters (APNCs) into metal-organic frameworks (MOFs) has been an efficient way to create new types of multifunctional crystalline porous materials. Such hybrids (APNCs@MOFs) provide ideal candidates for studying inherent structure-catalysis relationships owing to the well-defined compositions of both components. Moreover, modeling of APNCs@MOFs with precise structures would be more reliable. Herein, we have established an "Electrostatic Attraction Strategy" to synthesize APNCs@MOF catalysts and studied their performance as catalysts for the conversion of CO2. The synthetic strategy presented here has been proved to be general, as evidenced by the syntheses of various APNCs@MOF catalysts including all the combinations of [Au12Ag32(SR)30]4-, [Ag44(SR)30]4-, and [Ag12Cu28(SR)30]4- nanoclusters with ZIF-8, ZIF-67, and MHCF frameworks. In particular, the as-obtained Au12Ag32(SR)30@ZIF-8 composite shows excellent performance in capturing CO2 and converting phenylacetylene into phenylpropiolate under mild conditions (50 °C and ambient CO2 pressure) with a TON as high as 18164, far exceeding those of most known catalysts. What's more, the catalyst is very stable and reused 5 times without loss of catalytic activity. We anticipate that this general synthetic approach may open up a new frontier in the development of promising APNCs@MOF catalysts, which can be applied in a broad range of heterogeneous catalyses in the future.
- Sun, Lili,Yun, Yapei,Sheng, Hongting,Du, Yuanxin,Ding, Yimin,Wu, Pei,Li, Peng,Zhu, Manzhou
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supporting information
p. 15371 - 15376
(2018/08/17)
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- 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
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Oleic acid and oleylamine capped 3-D porous CeO2 nanocubes were synthesized by the hot injection method. The surface of the nanocube was modified with 2,4-dimethylphenol (DMP). The reducing and capping abilities of DMP to form Ag nanoparticles were explored to form noble metal nanoparticles over the porous CeO2 nanocubes support at room temperature. The surface modification and formation of Ag nanoparticles over the CeO2 support were thoroughly characterized with FTIR, UV-Vis spectroscopy, XRD, XPS, TEM, HRTEM, STEM, EDX and chemical mapping. This CeO2-Ag nanocomposite was found to have enhanced catalytic activities in the 'click reaction' as compared to unsupported Ag nanoparticles and porous CeO2 nanocubes; it was also found to have optimized catalytic activity in the carboxylation of terminal alkynes when Cs2CO3 was used as the base in DMF solvent at 80 °C. The reaction can give the desired product in yields as high as 98% under several experimental conditions via the green pathway. Recycling data showed that the catalyst could be reused five times without considerable loss of its activity and without any deterioration of physical conditions as observed by various characterization methods like TEM, EDX, XRD and XPS.
- Das, Subhasis,Mondal, Paramita,Ghosh, Swarbhanu,Satpati, Biswarup,Deka, Sasanka,Islam, Sk. Manirul,Bala, Tanushree
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p. 7314 - 7325
(2018/05/07)
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- Sequential protocol for C(sp)–H carboxylation with CO2: KOtBu-catalyzed C(sp)–H silylation and KOtBu-mediated carboxylation
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CO2 incorporation into C–H bonds is an important and interesting topic. Herein a sequential protocol for C(sp)–H carboxylation by employing a metal-free C–H activation/catalytic silylation reaction in conjunction with KOtBu-mediated carboxylation with CO2 was established, in which KOtBu catalyzes silylation of terminal alkynes to form alkynylsilanes at low temperature, and simultaneously mediates carboxylation of the alkynesilanes with atmospheric CO2. Importantly, the carboxylation further promotes the silylation, which makes the whole reaction proceed very rapidly. Moreover, this methodology is simple and scalable, which is characterized by short reaction time, wide substrate scope, excellent functional-group tolerance and mild reaction conditions, affording a range of corresponding propiolic acid products in excellent yields in most cases. In addition, it also allows for a convenient 13C-labeling through the use of 13CO2.
- Yu, Bo,Yang, Peng,Gao, Xiang,Yang, Zhenzhen,Zhao, Yanfei,Zhang, Hongye,Liu, Zhimin
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p. 449 - 456
(2018/02/06)
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- Method for preparing propiolic acid and derivatives thereof under mild condition
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The invention provides a novel method for preparing propiolic acid compounds through a domino reaction. The method comprises a step of subjecting terminal alkyne compounds, hydrosilane and CO2 to thedomino reaction under the catalysis action of Lewis base so as to obtain propiolic acid compounds. According to the invention, common Lewis base is used as a promoter, and corresponding propiolic acidcompounds containing different function groups can be efficiently produced through a reaction of the terminal alkyne compounds with hydrosilane and normal-pressure CO2 under a mild condition (a temperature of 40 DEG D). According to the method, CO2 is used as a raw material; the cheap Lewis base is used as the promoter; usage of precious metals is avoided; the domino reaction is employed; purification and separation of intermediates are not needed; and reaction conditions are mild. Thus, the method is an efficient cheap green synthetic method and has good industrial application value.
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Paragraph 0027; 0028
(2018/09/08)
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- 3 - Aryl methylacetylene acid and 3 - aryl methylacetylene ester preparation method of compound (by machine translation)
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The invention relates to a 3 - aryl methylacetylene acid compound preparation method: formula (I) shown phenylacetylene compound with carbon dioxide under the action of alkali, in solvent dimethyl sulfoxide in 40 - 70 °C under reaction, as shown in formula (II) of the 3 - aryl methylacetylene acid compounds, more than normal pressure of the body reaction in water-free, oxygen-free inert atmosphere, the reaction route is as follows: Wherein R1 Selected from hydrogen, alkyl, alkoxy, phenyl, nitro or halogen. The invention further provides a 3 - aryl methylacetylene ester preparation method of compound: adopting the above-mentioned method of the formula (II) is shown in the 3 - aryl methylacetylene acid compound, then adding the halogenated hydrocarbon or tosylates, after the in-situ reaction of the formula (III) is shown in the 3 - aryl methylacetylene ester compound: Wherein R2 Is selected from alkyl, benzyl or allyl. The method of the invention does not need to transition metal or rare earth metal catalyst, normal pressure reaction, mild condition, pervasive good substrate. (by machine translation)
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Paragraph 0053; 0055; 0056; 0061; 0063; 0065; 0067; 0069
(2018/10/19)
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- Binuclear molybdenum alkoxide as the versatile catalyst for the conversion of carbon dioxide
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The triply bonded dimolybdenum compound, Mo2(OtBu)6 (1), was investigated as a homogeneous catalyst for the conversion of CO2. The compound 1 acted as a rare example of a versatile catalyst with an impressive ability to transform CO2 into various valuable products, including propiolic acids, cyclic carbonates, and benzo[d]thiazole- and benzo[d]oxazolecarboxylic acids, in high yields with short reaction times and excellent selectivity at ambient pressure and low temperatures (25-75 °C). This is the first report of the application of a metal-metal bond-containing species in the catalytic conversion of CO2.
- Chen, Jing-Huo,Deng, Cheng-Hua,Fang, Sheng,Ma, Jian-Gong,Cheng, Peng
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supporting information
p. 989 - 996
(2018/03/13)
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- Copper-Catalyzed Decarboxylative/Click Cascade Reaction: Regioselective Assembly of 5-Selenotriazole Anticancer Agents
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A simple and efficient Cu-catalyzed decarboxylative/click reaction for the preparation of 1,4-disubstituted 5-arylselanyl-1,2,3-triazoles from propiolic acids, diselenides, and azides has been developed. The mechanistic study revealed that the intermolecular AAC reaction of an alkynyl selenium intermediate occurred. The resulting multisubstituted 5-seleno-1,2,3-triazoles were tested for in vitro anticancer activity by MTT assay, and compounds 4f, 4h, and 4p showed potent cancer cell-growth inhibition activities.
- Cui, Fei-Hu,Chen, Jing,Mo, Zu-Yu,Su, Shi-Xia,Chen, Yan-Yan,Ma, Xian-Li,Tang, Hai-Tao,Wang, Heng-Shan,Pan, Ying-Ming,Xu, Yan-Li
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supporting information
p. 925 - 929
(2018/02/22)
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- Central Doping of a Foreign Atom into the Silver Cluster for Catalytic Conversion of CO2 toward C?C Bond Formation
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Clusters with an exact number of atoms are of particular interest in catalysis. Their catalytic behaviors can be potentially altered with the addition or removal of a single atom. Now the effects of doping with a single foreign atom (Au, Pd, and Pt) into the core of an Ag cluster with 25 atoms on the catalytic properties are explored, where the foreign atom is protected by 24 Ag atoms (Au@Ag24, Pd@Ag24, and Pt@Ag24). The central doping of a single atom into the Ag25 cluster has a substantial influence on the catalytic performance in the carboxylation reaction of CO2 with terminal alkyne through C?C bond formation to produce propiolic acid. These studies reveal that the catalytic properties of the cluster catalysts can be dramatically changed with the subtle alteration by a single atom away from the active sites.
- Liu, Yuanyuan,Chai, Xiaoqi,Cai, Xiao,Chen, Mingyang,Jin, Rongchao,Ding, Weiping,Zhu, Yan
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supporting information
p. 9775 - 9779
(2018/07/31)
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- Flower-like AgNPs@m-MgO as an excellent catalyst for CO2 fixation and acylation reactions under ambient conditions
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Synthesis of fine chemicals from the chemical fixation of CO2 is one of the attractive research areas of today to utilise greenhouse gas CO2 in a greener pathway. A flower-like silver nanoparticle grafted mesoporous magnesium oxide (AgNPs@m-MgO) nanocomposite has been prepared by a facile in situ pathway. The materials are characterised by XRD, FTIR, UV-vis, TG-DTA, FESEM, HR-TEM and N2 adsorption-desorption studies. This AgNPs@m-MgO material showed a mesoporous nature with good surface area. It indicated brilliant catalytic activity for both the carboxylation of terminal alkynes by chemical fixation of CO2 (1 atm) and the acylation of various amines by utilizing acetic acid as a reagent in solvent-free conditions showing yields up to 98% and 99% of the propiolic acid and acetamide products, respectively. The reusability of this catalyst has also been verified and it showed high recycling efficiency for both the reactions together with no considerable catalyst deactivation.
- Chowdhury, Arpita Hazra,Ghosh, Swarbhanu,Islam, Sk. Manirul
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p. 14194 - 14202
(2018/08/28)
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- Release of Terminal Alkynes via Tandem Photodeprotection and Decarboxylation of o -Nitrobenzyl Arylpropiolates in a Flow Microchannel Reactor
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Photocleavable protecting groups (PPGs) offer a complementary protection paradigm compared to traditional protection groups. Herein, an o-nitrobenzyl (NB) PPG was employed to protect a variety of arylpropiolic acids. Upon a cascade of light-triggered photodeprotection in a microchannel reactor (residence times of 100-500 s), followed by Cu-catalyzed decarboxylation at 60 °C, the NB-protected arylpropiolic acid afforded a terminal alkyne. This terminal alkyne was further reacted in situ with an azide via click chemistry to yield a 1,2,3-triazole in a one-pot reaction. Furthermore, the effect of different substituents (methyl, vinyl, allyl, and phenyl) at the benzylic position on the rate of photodeprotection was studied. The quantum yields of photolysis for the benzylic-substituted esters were determined to be as high as 0.45 compared to the unsubstituted ester with a 0.08 quantum yield of photolysis.
- Tebikachew, Behabitu Ergette,B?rjesson, Karl,Kann, Nina,Moth-Poulsen, Kasper
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p. 1178 - 1185
(2018/04/23)
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- Method for synthesizing alpha-alkynyl substituted ether compounds
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The invention discloses a method for preparing alpha-alkynyl substituted ether compounds. The method comprises the following steps: taking propiolic acid as a raw material, and synthesizing substituted phenylpropiolic acid under conditions of substituted iodobenzene, 1,8-diazabicyclo[5.4.0]undec-7-ene, (beta-4)-platinu and dimethyl sulfoxide; taking substituted phenylpropiolic acid and p-bromophenol as raw materials, and synthesizing p-bromophenyl substituted phenylpropiolic acid ester under the conditions of 4-dimethylaminopyridine and N,N'-Dicyclohexylcarbodiimide; and performing an alkynylation reaction on the p-bromophenyl substituted phenylpropiolic acid ester in participation of tert-butyl hydroperoxide, cesium carbonate and tetrahydrofuran, and finally synthesizing alpha-alkynyl substituted ether products. According to the method disclosed by the invention, simple and readily available acetylene esters serve as an alkynylation reagent, and the target products, namely alpha-alkynyl substituted ether compounds, are synthesized in a green and environmental-friendly manner under mild conditions. The compounds play an important role in construction of multiple medical intermediates and bio-active structures.
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Paragraph 0025; 0027
(2018/04/01)
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- Microporous Nanotubes and Nanospheres with Iron-Catechol Sites: Efficient Lewis Acid Catalyst and Support for Ag Nanoparticles in CO2 Fixation Reaction
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FeIII-containing hyper-crosslinked microporous nanotubes (FeNTs) and nanospheres (FeNSs) are synthesized through the reaction of catechol and dimethoxymethane in the presence of FeCl3 or CF3SO3H. Both FeNTs and FeNSs demonstrate excellent catalytic activity in Lewis acid catalysis (hydrolysis and regioselective methanolysis of styrene oxide) and tandem catalysis involving a sequential oxidation-cyclization process, which selectively converts benzyl alcohol to 2-phenyl benzimidazole. Apart from Lewis acidity, the FeNTs and FeNSs also showed CO2 uptake capacities of 2.6 and 2.2 mmol g?1, respectively, at a pressure of 1 atm and temperature of 273 K. Furthermore, Ag nanoparticles are immobilized successfully on the surfaces of FeNTs and FeNSs by the liquid-phase impregnation method to prepare Ag@FeNT and Ag@FeNS nanocomposites, which show high catalytic activity for the selective fixation of CO2 to phenylacetylene to yield phenylpropiolic acid at 60 °C and 1 atm CO2 pressure. Hence, FeIII-catechol-containing hyper-crosslinked nanotubes and nanospheres have huge potential not only as Lewis acid catalysts, but also as excellent supports for immobilizing Ag nanoparticles in the design of a robust catalyst for the carboxylation of terminal alkynes, which has wide scope in catalysis and environmental research.
- Modak, Arindam,Bhanja, Piyali,Bhaumik, Asim
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p. 14189 - 14197
(2018/09/11)
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- CsF-promoted carboxylation of aryl(hetaryl) terminal alkynes with atmospheric CO2 at room temperature
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A CsF-promoted carboxylation of aryl(hetaryl) terminal alkynes with atmospheric CO2 in the presence of trimethylsilylacetylene was developed to give functionalized propiolic acid products at room temperature. A wide range of propiolic acids bearing functional groups was successfully obtained in good to excellent yields. Mechanistic studies demonstrate that in the carboxylation process the alkynylsilane intermediate was first in situ generated, which was then trapped by CO2, giving rise to the corresponding functionalized propiolic acids after acidification. The advantages of this approach include avoiding use of transition-metal catalysts, wide substrate scope together with excellent functional group tolerance, ambient conditions and a facile work-up procedure.
- Yu,Yang,Gao,Yang,Zhao,Zhang,Liu
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supporting information
p. 9250 - 9255
(2017/08/29)
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