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1.
Palladium nanoparticles immobilized on sepiolite–cyclodextrin nanosponge hybrid: Efficient heterogeneous catalyst for ligand‐ and copper‐free C─C coupling reactions
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A novel hybrid system composed of sepiolite clay and cyclodextrin nanosponge (CDNS) was prepared via reaction of Cl‐functionalized sepiolite with amine‐functionalized CDNS. CDNS–sepiolite was then applied for immobilization of Pd(0) nanoparticles. The resulting hybrid system, Pd@CDNS‐sepiolite, was characterized using various techniques and successfully used as an efficient and heterogeneous catalyst for ligand‐ and copper‐free Sonogashira and Heck coupling reactions under mild reaction conditions. Recycling experiments confirmed that Pd@CDNS‐sepiolite was recyclable and could be used for several consecutive reaction runs with slight Pd leaching and loss of catalytic activity. 相似文献
2.
《应用有机金属化学》2017,31(8)
Treatment of Ru3(CO)12 with an equivalent of (2‐phenyl‐1H ‐inden‐3‐yl)dicyclohexylphosphine ( 1 ) and (2‐pyridyl‐1H ‐inden‐1‐yl)dicyclohexylphosphine ( 4 ) in refluxing heptane gave the novel trinuclear ruthenium clusters (μ3‐η1:η2:η5–2‐phenyl‐3‐Cy2PC9H4)Ru3(CO)8 ( 1c ) and [μ2‐η1–2‐(pyridin‐2‐yl)‐3‐Cy2PC9H6]Ru3(CO)9 ( 4a ), respectively, via C ─ H bond cleavage. (2‐Mesityl‐1H ‐inden‐3‐yl)dicyclohexylphosphine ( 2 ) reacted with Ru3(CO)12 in refluxing heptane to give the trinuclear ruthenium cluster [μ‐2‐mesityl‐(3‐Cy2PC9H5)](μ2‐CO)Ru3(CO)9 ( 2c ) via C ─ H bond cleavage and carbonyl insertion. 2‐(Anthracen‐9‐yl)‐1H –inden‐3‐yldicyclohexylphosphine ( 3 ) reacted with Ru3(CO)12 in refluxing heptane to give the dinuclear ruthenium cluster [μ2‐η3:η3–2‐(anthracen‐9‐yl)‐3‐Cy2PC9H6]Ru2(CO)5 ( 3a ). The structures of 1c , 2c , 3a and 4a were fully characterized using IR and NMR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. These results suggest that the 2‐aryl substituent on the indenyl ring has a pronounced effect on the reaction and coordination modes of Ru3(CO)12. 相似文献
3.
《应用有机金属化学》2017,31(11)
An air‐stable, highly active and versatile method for C─N bond forming reactions is reported. Under mild conditions using a highly reusable support‐free Cu(II)–salen complex, structurally diverse N ‐aryl‐substituted compounds were obtained via direct C─N bond forming reaction of HN‐heterocycles with aryl iodides or three‐component C─N bond forming reaction of 2‐bromobenzaldehyde, aniline derivatives and sodium azide in good to excellent yields. C─N bond forming reaction for benzimidazole derivatives was also performed in the presence of the catalyst under ambient conditions. A series of hybrid benzimidazoles bearing morpholine, tetrazole and quinoxaline backbones were produced using this method. All reactions were performed in short times under air. The Cu(II) catalyst could be reused up to eight times in the direct cross‐coupling reaction of 9H –carbazole with iodobenzene without any decrease in its catalytic activity. 相似文献
4.
《应用有机金属化学》2017,31(3)
Polystyrene‐supported N ,N ‐dimethylethylenediamine Pd(II) complex C was used as an efficient catalyst for the synthesis of aromatic ketones via ortho ‐acylation of sp2 C─H bonds of 2‐arylpyridines with alcohols as effective coupling partners. The alcohols were oxidized with tert ‐butyl hydroperoxide to their corresponding aldehydes in situ and efficiently coupled with 2‐arylpyridines to form aryl ketones under solvent‐free conditions. Furthermore, catalyst C could be easily recovered by simple filtration and reused for five cycles without any significant decrease in its activity. 相似文献
5.
Zirconium oxide complex anchored on boehmite nanoparticles as highly reusable organometallic catalyst for C–S and C–O coupling reactions
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Boehmite nanoparticles were prepared by a simple and inexpensive procedure in water using commercially available materials without inert atmosphere. Then, the surface of the boehmite nanoparticles was modified using 3‐mercaptopropyltrimethoxysilane and subsequently zirconium oxide was supported on the modified surface. Zirconium oxide supported on boehmite nanoparticles (Pr.S‐ZrO@boehmite) was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and inductively coupled plasma technique. The catalytic application of Pr.S‐ZrO@boehmite was studied in C–O and C–S coupling reactions for synthesis of valuable compounds such as ether and sulfide derivatives. All products were obtained in good to excellent yields and the catalyst could be recovered and reused several times without significant loss of catalytic efficiency. Furthermore, zirconium oxide is rarely used as catalyst for cross‐coupling reactions. 相似文献
6.
Biochar is a stable and carbon‐rich solid which has a high density of carbonyl, hydroxyl and carboxylic acid functional groups on its surface. In this work, the surface of biochar nanoparticles (BNPs) was modified with 3‐choloropropyltrimtoxysilane and further 2‐(thiophen‐2‐yl)‐1H‐benzo[d]imidazole was anchored on its surface. Then, palladium nanoparticles were fabricated on the surface of the modified BNPs and further the catalytic application was studied as recyclable biocatalyst in carbon–carbon coupling reactions such as Suzuki–Miyaura and Heck–Mizoroki cross‐coupling reactions. The structure of the catalyst was characterized using scanning electron microscopy, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis, X‐ray diffraction and atomic absorption spectroscopy. The catalyst can be reused several times without a decrease in its catalytic efficiency. In addition to the several advantages reported, application of biochar as catalyst support for the first time is a major novelty of the present work. 相似文献
7.
Catalyst‐Dependent Chemoselective Formal Insertion of Diazo Compounds into C−C or C−H Bonds of 1,3‐Dicarbonyl Compounds
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Zhaohong Liu Dr. Paramasivam Sivaguru Prof. Giuseppe Zanoni Prof. Edward A. Anderson Prof. Xihe Bi 《Angewandte Chemie (International ed. in English)》2018,57(29):8927-8931
A catalyst‐dependent chemoselective one‐carbon insertion of diazo compounds into the C?C or C?H bonds of 1,3‐dicarbonyl species is reported. In the presence of silver(I) triflate, diazo insertion into the C(=O)?C bond of the 1,3‐dicarbonyl substrate leads to a 1,4‐dicarbonyl product containing an all‐carbon α‐quaternary center. This reaction constitutes the first example of an insertion of diazo‐derived carbenoids into acyclic C?C bonds. When instead scandium(III) triflate was applied as the catalyst, the reaction pathway switched to formal C?H insertion, affording 2‐alkylated 1,3‐dicarbonyl products. Different reaction pathways are proposed to account for this powerful catalyst‐dependent chemoselectivity. 相似文献
8.
Iridium‐Catalyzed Intramolecular Methoxy C−H Addition to Carbon–Carbon Triple Bonds: Direct Synthesis of 3‐Substituted Benzofurans from o‐Methoxyphenylalkynes
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Takeru Torigoe Dr. Toshimichi Ohmura Prof. Michinori Suginome 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10415-10419
Catalytic hydroalkylation of an alkyne with methyl ether was accomplished. Intramolecular addition of the C?H bond of a methoxy group in 1‐methoxy‐2‐(arylethynyl)benzenes across a carbon–carbon triple bond took place efficiently either in toluene at 110 °C or in p‐xylene at 135 °C in the presence of an iridium catalyst. The initial 5‐exo cyclization products underwent double‐bond migration during the reaction to give 3‐(arylmethyl)benzofurans in high yields. 相似文献
9.
《应用有机金属化学》2017,31(8)
Graphene oxide was functionalized with benzimidazole for palladium immobilization. The resultant graphene–benzimidazole‐supported palladium composite (G‐BI‐Pd) was characterized using infrared and Raman spectroscopies, transmission electron microscopy and energy‐dispersive X‐ray spectroscopy. G‐BI‐Pd showed excellent catalytic activity and fast reaction kinetics in the aqueous‐phase Suzuki–Miyaura reaction of aryl iodides and bromides with phenylboronic acid under relatively mild conditions (5–25 min, 80 °C). The catalyst can be used several times without any significant loss of its catalytic activity. 相似文献
10.
《应用有机金属化学》2017,31(4)
PdCo bimetallic nanoparticles (NPs) were decorated over three‐dimensional graphene (3DG) in a facile manner by reducing palladium chloride and cobalt chloride in the presence of ethylene glycol as reducing, stabilizing and dispersing agent. The PdCo NPs–3DG nanocomposite was characterized using Raman, X‐ray photoelectron and energy‐dispersive X‐ray spectroscopies, X‐ray diffraction and transmission electron microscopy. The obtained catalyst can act as an efficient catalyst for Sonogashira cross‐coupling reactions in aqueous media. 相似文献
11.
We present green methodologies for one‐pot and odourless syntheses of unsymmetric and symmetric diaryl sulfides via C─O bond activation using NiFe2O4 magnetic nanoparticles as a reusable heterogeneous nanocatalyst. The synthesis of unsymmetric sulfides is performed using the cross‐coupling reaction of phenolic esters such as acetates, triflates and tosylates with arylboronic acid/S8 or triphenyltin chloride/S8 as thiolating agents in the presence of base and NiFe2O4 magnetic nanoparticles as a catalyst in poly(ethylene glycol) as solvent at 60–85°C. Also, the synthesis of symmetric diaryl sulfides from phenolic compounds using S8 as the sulfur source and NiFe2O4 as catalyst in dimethylformamide at 120°C is described. Using these protocols, the syntheses of various unsymmetric and symmetric sulfides become easier than using the available protocols due to the use of a magnetically reusable bimetallic nanocatalyst and avoiding the use of thiols and aryl halides. 相似文献
12.
Bifunctional RuII‐Complex‐Catalysed Tandem C−C Bond Formation: Efficient and Atom Economical Strategy for the Utilisation of Alcohols as Alkylating Agents
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Bivas Chandra Roy Kaushik Chakrabarti Sujan Shee Subhadeep Paul Dr. Sabuj Kundu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):18147-18155
Catalytic activities of a series of functional bipyridine‐based RuII complexes in β‐alkylation of secondary alcohols using primary alcohols were investigated. Bifunctional RuII complex ( 3 a ) bearing 6,6’‐dihydroxy‐2,2’‐bipyridine (6DHBP) ligand exhibited the highest catalytic activity for this reaction. Using significantly lower catalyst loading (0.1 mol %) dehydrogenative carbon?carbon bond formation between numerous aromatic, aliphatic and heteroatom substituted alcohols were achieved with high selectivity. Notably, for the synthesis of β‐alkylated secondary alcohols this protocol is a rare one‐pot strategy using a metal–ligand cooperative RuII system. Remarkably, complex 3 a demonstrated the highest reactivity compared to all the reported transition metal complexes in this reaction. 相似文献
13.
Takeshi Fujita Kohei Fuchibe Junji Ichikawa 《Angewandte Chemie (International ed. in English)》2019,58(2):390-402
The activation of carbon–fluorine (C?F) bonds is an important topic in synthetic organic chemistry. Metal‐mediated and ‐catalyzed elimination of β‐ or α‐fluorine proceeds under milder conditions than oxidative addition to C?F bonds. The β‐ or α‐fluorine elimination is initiated from organometallic intermediates having fluorine substituents on carbon atoms β or α to metal centers, respectively. Transformations through these elimination processes (C?F bond cleavage), which are typically preceded by carbon–carbon (or carbon–heteroatom) bond formation, have been increasingly developed in the past five years as C?F bond activation methods. In this Minireview, we summarize the applications of transition‐metal‐mediated and ‐catalyzed fluorine elimination to synthetic organic chemistry from a historical perspective with early studies and from a systematic perspective with recent studies. 相似文献
14.
Cobalt‐Catalyzed Tandem C−H Activation/C−C Cleavage/C−H Cyclization of Aromatic Amides with Alkylidenecyclopropanes
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Dr. Mingliang Li Prof. Dr. Fuk Yee Kwong 《Angewandte Chemie (International ed. in English)》2018,57(22):6512-6516
A cobalt‐catalyzed chelation‐assisted tandem C?H activation/C?C cleavage/C?H cyclization of aromatic amides with alkylidenecyclopropanes is reported. This process allows the sequential formation of two C?C bonds, which is in sharp contrast to previous reports on using rhodium catalysts for the formation of C?N bonds. Here the inexpensive catalyst system exhibits good functional‐group compatibility and relatively broad substrate scope. The desired products can be easily transformed into polycyclic lactones with m‐CPBA. Mechanistic studies revealed that the tandem reaction proceeds through a C?H cobaltation, β‐carbon elimination, and intramolecular C?H cobaltation sequence. 相似文献
15.
Transition‐metal‐catalyzed C–H activation and C–C formation have been receiving considerable attention because of their high atom economy and synthesis efficiency. Iron is widely used in catalytic reactions because it has the advantages of abundance, low cost, accessibility, and environmental friendliness. In recent years, research on the Fe‐catalyzed C–H activation of C–C formation has made considerable progress. This paper summarizes latest studies on iron‐catalyzed C–H activation, classifies the catalysts according to the different valence states of iron, and expounds the catalytic mechanism. 相似文献
16.
《Chemical record (New York, N.Y.)》2018,18(2):165-229
The carbon‐carbon and carbon‐heteroatom bonds catalytic formation is among the most significant reactions in organic synthesis which extensively applied for synthesis of natural products, heterocycles, dendrimers, biologically active molecules and useful compounds. This review provides the latest advances in the preparation of graphene supported metal nanoparticles and their application in the catalytic formation of both carbon‐carbon (C−C) and carbon‐heteroatom (C−X) bonds including the Suzuki, Heck, Hiyama, Ullmann, Buchwald and Sonogashira coupling reactions. Numerous examples are given concerning the use of these catalysts in C−C and C−X coupling reactions along with the reliable and simple preparation methods of these catalysts, their characterization and catalytic properties and also the recycling possibilities. 相似文献
17.
Density functional theory was employed to investigate rhodium(I)‐catalyzed C–C bond activation of siloxyvinylcyclopropanes and diazoesters. The B3LYP/6‐31G(d,p) level (LANL2DZ(f) for Rh) was used to optimize completely all intermediates and transition states. The computational results revealed that the most favorable pathway was the channel forming the methyl‐branched acyclic product p1 in path A (cyclooctadiene (cod) as the ligand), and the oxidative addition was the rate‐determining step for this channel. It proceeded mainly through the complexation of diazoester to rhodium, rhodium–carbene formation, coordination of siloxyvinylcyclopropane, oxidative addition (C2–C3 bond cleavage) of siloxyvinylcyclopropane, carbene migratory insertion, β‐hydrogen elimination and reductive elimination. The complexation of diazoester to rhodium occurred prior to the coordination of siloxyvinylcyclopropane. Also, the role of the ligands cod, chlorine and 1,4‐dioxane, the effect of di‐rhodium catalyst and the solvent effect are discussed in detail. 相似文献
18.
《应用有机金属化学》2017,31(9)
An efficient trans ‐PdCl2(NH2CH2COOH)2‐catalyzed direct C3‐cyanation of indole C─H bonds is described. Notably, free (N─H)‐indoles reacted smoothly using the procedure, and the desired product 3‐cyanoindoles were obtained in good to excellent yields. 相似文献
19.
M. Lakshmi Kantam Chandrakanth Gadipelly Gunjan Deshmukh K. Rajender Reddy Suresh Bhargava 《Chemical record (New York, N.Y.)》2019,19(7):1302-1318
Activation of C?H bonds and their application in cross coupling chemistry has received a wider interest in recent years. The conventional strategy in cross coupling reaction involves the pre‐functionalization step of coupling reactants such as organic halides, pseudo‐halides and organometallic reagents. The C?H activation facilitates a simple and straight forward approach devoid of pre‐functionalization step. This approach also addresses the environmental and economical issues involved in several chemical reactions. In this account, we have reported C?H bond activation of small organic molecules, for example, formamide C?H bond can be activated and coupled with β‐dicarbonyl or 2‐carbonyl substituted phenols under oxidative conditions to yield carbamates using inexpensive copper catalysts. Phenyl carbamates were successfully synthesized in moderate to good yields by cross dehydrogenative coupling (CDC) of phenols with formamides using copper catalysts in presence of a ligand. We have also prepared unsymmetrical urea derivatives by oxidative cross coupling of formamides with amines using copper catalysts. Synthesis of N,N‐dimethyl substituted amides, 5‐substituted‐γ‐lactams and α‐acyloxy ethers was carried out from carboxylic acids using recyclable CuO nanoparticles. Copper nanoparticles afforded N‐aryl‐γ‐amino‐γ‐lactams by oxidative coupling of aromatic amines with 2‐pyrrolidinone. Reusable transition metal HT‐derived oxide catalyst was used for the synthesis of N,N‐dimethyl substituted amides by the oxidative cross‐coupling of carboxylic acids and substituted benzaldehydes. Overview of our work in this area is summarized. 相似文献
20.
A novel radical‐based approach for the iron‐catalyzed selective cleavage of acetal‐derived alkylsilyl peroxides, followed by the formation of a carbon–carbon bond is reported. The reaction proceeds under mild reaction conditions and exhibits a broad substrate scope with respect to the acetal moiety and the carbon electrophile. Mechanistic studies suggest that the present reaction proceeds through a free‐radical process involving carbon radicals generated by the homolytic cleavage of a carbon–carbon bond within the acetal moiety. A synthetic application of this method to sugar‐derived alkylsilyl peroxides is also described. 相似文献