- Self-assembled M12L24 nanospheres as a reaction vessel to facilitate a dinuclear Cu(i) catalyzed cyclization reaction
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The application of large M12L24 nanospheres allows the pre-concentration of catalysts to reach high local concentrations, facilitating reactions that proceed through dinuclear mechanisms. The mechanism of the copper(i)-catalyzed cyclization of 4-pentynoic acid has been elucidated by means of a detailed mechanistic study. The kinetics of the reaction show a higher order in copper, indicating the formation of a bis-Cu intermediate as the key rate determining step of the reaction. This intermediate was further identified during catalysis by CIS-HRMS analysis of the reaction mixture. Based on the mechanistic findings, an M12L24 nanosphere was applied that can bind up to 12 copper catalysts by hydrogen bonding. This pre-organization of copper catalysts in the nanosphere results in a high local concentration of copper leading to higher reaction rates and turnover numbers as the dinuclear pathway is favored.
- Gonell, Sergio,Caumes, Xavier,Orth, Nicole,Ivanovi?-Burmazovi?, Ivana,Reek, Joost. N. H.
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- "water soluble" palladium nanoparticle engineering for C-C coupling, reduction and cyclization catalysis
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The use of Pd nanoparticles (Pd-NPs) to realize several important organic reactions allows efficient catalysis with low metal loading (1000 ppm), hence providing a greener catalytic system. However, to be truly green Pd-NPs need to be synthesized in a sustainable manner and be able to react in aqueous media in order to avoid the use of organic solvents. Here we describe an original and eco-friendly synthesis of Pd-NPs (using benign reactants and simple conditions) perfectly stable in water. Remarkably, this synthesis allows for control over their size and morphology by simply tuning the pH of the stabilizer. We then evaluate the catalytic efficiency of these Pd-NPs on six different model reactions (Suzuki Miyaura, Sonogashira, Heck, nitrophenol reduction and pentynoic cycloisomerization) in aqueous media. We show that the stabilizer structure influences the activity owing to its ability to promote the mass transfer of the organic substrates towards the NP surface in the aqueous environment. Finally, catalytic evaluations show that our nano-catalysts prepared in an eco-friendly manner are among the best catalysts described so far in the literature in each case, with high turnover frequencies reached with a low loading of palladium.
- Iben Ayad,Belda Marín,Colaco,Lefevre,Méthivier,Ould Driss,Landoulsi,Guénin
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- PALLADIUM(II) CATALYZED CYCLIZATION OF ALKYNOIC ACIDS
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Under the catalytic action of palladium(II) in the presence of triethylamine, 3-, 4-, and 5-alkynoic acids afford 3-buten-4-olides, 4-penten-4-olides,and 5-hexen-5-olide, respectively, in good to excellent yields.
- Lambert, Claude,Utimoto, Kiitiro,Nozaki, Hitosi
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- Metal-ligand cooperation in the cycloisomerization of alkynoic acids with indenediide palladium pincer complexes
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Indenediide Pd complexes 1a-c are shown to very efficiently catalyze the cycloisomerization of alkynoic acids into alkylidene lactones via metal-ligand cooperation (TON up to 2000). Complexes 1a-c are competent toward a broad range of alkynoic acids, including functionalized and internal ones, and give access to 5- as well as 6- and 7-membered lactones in excellent yields and with very high selectivities.
- Nebra, Noel,Monot, Julien,Shaw, Rosie,Martin-Vaca, Blanca,Bourissou, Didier
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- Cyclisations of alkynoic acids using copper(I) arylspiroborate complexes
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In this study we have studied the synthesis, characterization and catalytic activity of phosphinocopper(I) complexes [Cu(PPh3)3(NCCH3)][B(O2C6H4-4-R)2] (3a: R = H; 3b: R = Me; 3c
- Lee, Graham M.,Bowes, Eric G.,Vogels, Christopher M.,Decken, Andreas,Westcott, Stephen A.
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- Gold Functionalized Platinum M12L24-Nanospheres and Their Application in Cyclization Reactions
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Nanospheres can be formed by combining 24 bispyridinyl building blocks with a palladium or platinum precursor. These spheres can be functionalized on the inside with a gold(I) chloride complex leading to a high local concentration of gold(I) complexes. The high local concentration makes the neutral gold species an active catalyst. Furthermore, the platinum-gold spheres can be post-modified with a silver(I) salt to form cationic gold(I) catalysts. The platinum assemblies are demonstrated to be stable in the presence of various substrates and as a result several cyclization reactions have been carried out using these new spheres as catalysts. Higher conversions in a [4+2] cycloaddition are observed for the sphere catalyst compared to the mono-nuclear analogues. Also the cyclization of 1,6-enynes can be facilitated by the confined gold catalyst and high activity is observed in the activation of allenes. For the lactonization of alkynoic acids, a different selectivity is observed compared to a standard gold(I) complex, demonstrating that the high local concentration due to a confined space can induce other selectivity in catalysis.
- Leenders, Stefan H. A. M.,Dürr, Maximillian,Ivanovic-Burmazovic, Ivana,Reek, Joost N. H.
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- Cyclisation of acetylenic carboxylic acids and acetylenic alcohols to oxygen-containing heterocycles using cationic rhodium(I) complexes
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Square planar cationic rhodium(I) dicarbonyl complexes [{Rh((mim)2CH2)(CO)2}+BPh -4] (1) and [{Rh((mBnzim)2CH2)-(CO)2}+BPh -4/su
- Elgafi, Sarah,Field, Leslie D.,Messerle, Barbara A.
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- Synthesis and characterization of oxygen/sulfur-bridged incomplete cubane-type clusters, [M3S4(Tpe)3]+ and [M 3OS3(Tpe)3]+ (M = Mo and W), and a mixed-metal cubane-type cluster, [Mo3
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The reaction of [Mo3S4(H2O) 9]4+(1) and [Mo3OS3(H 2O)9]4+ (2) with hydrotris(pyrazolyl)ethanol (HTpe) ligands produced [Mo3S4/su
- Yoshida, Ryouichi,Shibahara, Takashi,Akashi, Haruo
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- Palladium pincer complexes featuring an unsymmetrical SCN indene-based ligand with a hemilabile pyridine sidearm
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A new unsymmetrical indene-based pro-ligand featuring thiophosphinoyle and methylpyridine sidearms 2 was prepared. Coordination and cyclometalation in the presence of [PdCl2(PhCN)2] and PS-DIEA afforded three well-defined 2-indenyl S
- Brunel, Paul,Lhardy, Chloé,Mallet-Ladeira, Sonia,Monot, Julien,Martin-Vaca, Blanca,Bourissou, Didier
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- Enhanced catalytic performance of indenediide palladium pincer complexes for cycloisomerization: Efficient synthesis of alkylidene lactams
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New SCS Pd pincer complexes featuring a noninnocent indenediide backbone show high catalytic activity in cycloisomerization. A variety of alkylidene lactams (five- to seven-membered rings) have been prepared efficiently from N-tosyl alkynylamides, and goo
- Espinosa-Jalapa, Noel ángel,Ke, Diandian,Nebra, Noel,Le Goanvic, Lucas,Mallet-Ladeira, Sonia,Monot, Julien,Martin-Vaca, Blanca,Bourissou, Didier
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- Triazolediylidenes: A versatile class of ligands for the preparation of discrete molecules of homo- and hetero-binuclear complexes for improved catalytic applications
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Double trouble: A series of complexes of rhodium and iridium has been obtained with a triazolediylidene ligand, which behaves as an extraordinarily versatile janus-type ligand to form dinuclear complexes. The dinuclear complexes showed improved catalytic
- Mas-Marza, Elena,Mata, Jose A.,Peris, Eduardo
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- A case study of proton shuttling in palladium catalysis
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The mechanism of alkynoic acid cycloisomerization with SCS indenediide Pd pincer complexes has been investigated experimentally and computationally. These studies confirmed the cooperation between the Pd center and the backbone of the pincer ligand, and r
- Monot, Julien,Brunel, Paul,Kefalidis, Christos E.,Espinosa-Jalapa, Noel ángel,Maron, Laurent,Martin-Vaca, Blanca,Bourissou, Didier
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- Das s-cis-/s-trans-Konformerengleichgewicht bei Allencarbonsaeureestern
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The following UV, and 1H-NMR. spectroscopic investigations of the allenic compounds 1-9 (cf.Scheme 2) refer for the first time on a concrete experimental base to the preferred s-trans conformation of the allenic esters 1-6.With an additional allenic increment of 12 nm, the well established Woodward-Fieser rules in UV. spectroscopy could be extended on conjugated allenic compounds for the calculations of the (?->?*)-type band positions as well as for the prediction of the s-cis/s-trans conformational fraction (cf.Scheme 1).From 1H-NMR. shift experiments we conclude, that even small structural changes at the molecular framework have a measurable influence on the conformational equilibrium.In contrast to the situation in similarly α,β-unsaturated compounds (14 and 15), the allenic esters (1 and 4) exhibit preferentially s-trans conformations (cf.Scheme 3), but in both cases, the equilibrium is displaced toward s-cis conformation, when the α-position is methyl substituted (e.g. 14->15 and 1->4).
- Lang, Robert W.,Hansen, Hans-Juergen
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- Sustainable Gold Catalysis in Water Using Cyclodextrin-tagged NHC-Gold Complexes
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The synthesis of 10 water-soluble β-cyclodextrin-tagged NHC-gold(I) complexes is described. Key steps are nucleophilic substitutions, as well as, copper-(CuAAC)- and ruthenium-(RuAAC)-catalyzed azide alkyne cycloadditions. Whereas the CuAAC reliably affor
- Sak, Hülya,Mawick, Matthias,Krause, Norbert
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- Investigation of the Deactivation and Reactivation Mechanism of a Heterogeneous Palladium(II) Catalyst in the Cycloisomerization of Acetylenic Acids by in Situ XAS?
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A well-studied heterogeneous palladium(II) catalyst used for the cycloisomerization of acetylenic acids is known to be susceptible to deactivation through reduction. To gain a deeper understanding of this deactivation process and to enable the design of a
- Yuan, Ning,Gudmundsson, Arnar,Gustafson, Karl P. J.,Oschmann, Michael,Tai, Cheuk-Wai,Persson, Ingmar,Zou, Xiaodong,Verho, Oscar,Bajnóczi, éva G.,B?ckvall, Jan-E.
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- Impregnated palladium on magnetite as a water compatible catalyst for the cycloisomerization of alkynoic acid derivatives
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This work describes the catalytic activity of palladium(ii) species in the cycloisomerization of alkynoic acids and their derivatives in aqueous media as well as in Deep Eutectic Solvents (DESs), with one of the lowest metal catalyst loadings reported so far in the literature. Different substrates such as terminal and internal alkynes or alkynyl sulfonylimides were studied, obtaining selectivity either to the cyclic compound or the hydrolysed keto derivative. This new system avoids the use of harmful solvents and employs very efficient and recoverable heterogeneous catalysts.
- Saavedra, Beatriz,Pérez, Juana M.,Rodríguez-álvarez, María J.,García-álvarez, Joaquín,Ramón, Diego J.
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- Sol–Gel Immobilized N-Heterocyclic Carbene Gold Complex as a Recyclable Catalyst for the Rearrangement of Allylic Esters and the Cycloisomerization of γ-Alkynoic Acids
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The synthesis of a bis-silylated (NHC)AuCl (NHC=N-heterocyclic carbene) complex and the formation of a hybrid silica material by the sol–gel process by cogelification with tetraethylorthosilicate under fluoride catalysis are described. This material was characterized by using 29Si solid-state NMR spectroscopy, N2 sorption measurements, electron microscopy, and elemental analysis. It was tested as a reusable catalyst in the rearrangement of allylic esters in conjunction with a silver salt under microwave conditions and it displayed a much better performance than a homogeneous analogue. This catalyst is active and recyclable in the cycloisomerization of γ-alkynoic acids to five-membered enol-lactones at room temperature in two reaction media, a toluene/water biphasic system and a deep eutectic solvent.
- Ferré, Meritxell,Catto?n, Xavier,Wong Chi Man, Michel,Pleixats, Roser
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- SILVER ASSISTED HETEROCYCLIZATION OF ACETYLENIC COMPOUNDS
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Silver assisted heterocyclization of acetylenic alcohols or acids provides an easy and mild access to α-methylene oxygenated heterocycles.
- Pale, Patrick,Chuche, Josselin
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- Group VIII carbamoyl complexes as catalysts for alkyne hydrocarboxylation and electrochemical proton reduction
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A series of group VIII carbamoyl complexes, [M(2-NHC(O)C5H4N)(CO)2(2-SC5H4N)] [where M = Fe, Ru and Os], was found to be efficient and regioselective catalysts for the intramolecular hydroxycarboxylat
- Barik, Chandan Kr,Tessensohn, Malcolm E.,Webster, Richard D.,Leong, Weng Kee
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- Symmetrical and Non-symmetrical Pd (II) Pincer Complexes Bearing Mesoionic N-heterocyclic Thiones: Synthesis, Characterizations and Catalytic Properties
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In contrast to well-established symmetrical pincer complexes, non-symmetrical metal pincers with the loss of C2v symmetry are much less studied. In this work, mesoionic NHTs (NHTs = N-heterocyclic thiones), which can be viewed as the sulfur adducts of mesoionic carbenes, are incorporated into pincer complexes for the first time. Two symmetrical and non-symmetrical phenylene-bridged bis (NHT) compounds 3a/3b were synthesized as proligands via a “cycloaddition-alkylation-thionation” reaction sequence. In a case to access bis (NHT) compound 3c, N-dealkylation reactions occurred. The carbene NMR signals of NHTs are only partially correlated to the π-accepting abilities of carbenes, which is different from Bertrand's carbene-phosphinidene system. The structural analysis of 3a/3b indicates that they possess C-S partial double bonds. 3a and 3b served as the precursors to access two aryl anion-linked [SCS/S′] pincer complexes 6a/6b. An external base proved to be essential for this cyclopalladation process. The catalytic properties of 6a/6b in the cycloisomerizations of alkynoic acids have been examined. Finally, non-symmetrical complex 6a shows superior catalytic performance in such transformations contrasting to its symmetrical counterpart 6b.
- Yan, Xuechao,Zhang, Bo,Zhang, Xin,Wang, Haiying,Duan, Yu-Ai,Guo, Shuai
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- Au2O3 as a stable and efficient catalyst for the selective cycloisomerization of γ-acetylenic carboxylic acids to γ-alkylidene-γ-butyrolactones
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The high potential of commercially available Au2O3 as a catalyst in the cyclization of alkynes bearing carboxylic acids to the corresponding γ-alkylidene-γ-butyrolactones through a general, efficient and easy procedure is presented. The reaction shows a high degree of chemo-, regio-, and stereoselectivity. The 5-exo mode of cyclization and anti auration are a general trend for the Au2O3 catalyst. Georg Thieme Verlag Stuttgart.
- Toullec, Patrick Yves,Genin, Emilie,Antoniotti, Sylvain,Genêt, Jean-Pierre,Michelet, Véronique
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- Cu(I)-catalyzed intramolecular cyclization of alkynoic acids in aqueous media: A "click side reaction"
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(Chemical Equation Presented) Alkynoic acids, in particular, 4-pentynoic acid derivatives, undergo intramolecular cyclizations to enol lactones under reaction conditions typically applied for the Cu(I)-catalyzed cycloaddition of terminal alkynes and azide
- Mindt, Thomas L.,Schibli, Roger
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- Water-soluble Gold(I) and Gold(III) complexes with sulfonated N-heterocyclic carbene ligands: Synthesis, characterization, and application in the catalytic cycloisomerization of γ-alkynoic acids into enol-lactones
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Zwitterionic imidazolium salts bearing 3-sulfonatopropyl, and 2-pyridyl, 2-picolyl, and 2-pyridylethyl substituents have been synthesized and employed as precursors for the preparation of novel water-soluble Au(I)- and Au(III)-NHC complexes of general com
- Tomas-Mendivil, Eder,Toullec, Patrick Y.,Borge, Javier,Conejero, Salvador,Michelet, Veronique,Cadierno, Victorio
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- Atom transfer radical addition and enol-ester synthesis catalyzed by Ru-vinylidene complexes
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Ru-vinylidene complexes, Cl2Ru{=C=C(H)tBut}(PCy3)(L) (L=PCy3 or N-heterocyclic carbenes) reveal themselves as a versatile catalyst for the atom transfer radical addition (ATRA) of polyhalogenated alkanes to olefins, such as methylmethacrylate, styrene and 1-octene. Furthermore, these systems are excellent catalysts for the nucleophilic addition of carboxylic acids to terminal alkynes and yielded exclusively alk-1-en-2-yl esters. These complexes can also be transformed to their cationic counterparts by treating the neutral complexes with AgBF4 and their catalytic potential in ATRA and vinylation reaction are investigated.
- Opstal, Tom,Verpoort, Francis
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- Catalytic application of a Ru-alkylidene in the nucleophilic addition of several carboxylic acids on terminal alkynes and the homo-coupling of 1-alkynes
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Thermal treatment of Ru-alkylidene (4) bearing a triazol-5-ylidene (NHC) ligand (2) at 110°C and addition of a terminal alkyne generates a ruthenium vinylidene. The thermolysed Ru-alkylidene catalyses the vinylation and dimerisation of 1-alkynes. The nucleophilic addition of acetic acid on terminal alkynes proceeds smoothly and regioselective towards the Markovnikov addition. The addition reaction can be tuned by changing the acidity of the carboxylic acid. At increasing acidity, higher conversion of the triple bond is obtained and the vinylation/dimerisation ratio increases. The direct coupling between two 1-alkynes shows a reactivity order, which decreases from 1-octyne > 1,7-octadiyne > phenylacetylene > 3,3 dimethyl-1-butyne. The regioselectivity is strongly dependent on the nature of the terminal alkyne.
- Melis, Karen,De Vos, Dirk,Jacobs, Pierre,Verpoort, Francis
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- Copper-catalyzed tandem reaction in ionic liquid: An efficient reusable catalyst and solvent media for the synthesis of fused poly hetero cyclic compounds
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Herein we report a copper catalyzed tandem reaction for the synthesis of therapeutically important pyrrolo-/pyrido[2,1-b] benzo[d][1,3]oxazin-1-ones from 2-aminobezyl alcohols using alkynoic acids under ligand and base free conditions in the presence of a green solvent medium [bmim]OTf. The catalyst and solvent were successfully recycled and reused.
- Naidu, Shivaji,Reddy, Sabbasani Rajasekhara
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- Cyclisation of Alkynecarboxylic Acids: a Route to an Oxaspirolactone
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Pent-4-ynoic acid, in various alcohols, was cyclised in the presence of yellow mercury(II) oxide to 4,5-dihydro-5-alkoxy-5-methylfuran-2(3H)-ones; 8-hydroxyoct-4-ynoic acid was also cyclised in dimethylformamide to 1,6-dioxaspirodecan-2-one in good y
- Yamamoto, Makoto,Yoshitake, Makoto,Yamada, Kazutoshi
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- The phosphinoboration of 2-diphenylphosphino benzaldehyde and related aldimines
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We have investigated the addition of a simple phosphinoboronate ester, Ph2PBpin (pin = 1,2-O2C2Me4), to 2-diphenylphosphinobenzaldehyde (2-Ph2PC6H4C(O)H) and related aldimine derivatives (2-Ph2PC6H4C(NR)H) as a simple and effective strategy for generating unique diphosphine ligands bearing a pendant Lewis-acid Bpin group. These reactions proceed selectively to give one new product where the phosphide fragment has added to the aldehyde (or imine) carbon atom and the electron-deficient boron group has added to the electron-rich heteroatom. Preliminary studies show these new compounds can ligate to Pd(II) and Pt(II) metal centres. These novel metal complexes, as well as the organic soluble [MCl2(coe)]2 (M = Pd, Pt, coe = cis-cyclooctene) compounds, have been shown to be effective precatalysts in the cyclisation of alkynoic acids to give the corresponding exo-dig cyclic lactones. Reactions employing these metal complexes also generated unusual endo-dig cyclic lactones not traditionally observed in these cyclisation reactions. For instance, reactions of 4-pentynoic acid also afforded significant amounts of α-angelica lactone, a biologically-important compound traditionally prepared via the catalytic dehydration and cyclisation of levulinic acid.
- Kindervater, Meagan B.,Binder, Justin F.,Baird, Samuel R.,Vogels, Christopher M.,Geier, Stephen J.,Macdonald, Charles L.B.,Westcott, Stephen A.
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- Gold nanoparticles stabilized by PEG-tagged imidazolium salts as recyclable catalysts for the synthesis of propargylamines and the cycloisomerization of γ-alkynoic acids
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We report the synthesis of PEGylated imidazolium (bromide and tetrafluoroborate) and tris-imidazolium (bromide) salts containing triazole linkers, and their use as stabilizers for the preparation of water-soluble gold nanoparticles by reduction of tetrachloroauric acid with sodium borohydride. The nanomaterials have been characterized. The X-Ray Photoelectron Spectroscopy (XPS) indicated the presence of Au(i) and Au(0) species, the oxidized form being more abundant in the nanomaterial derived from the tris-imidazolium bromide. The catalytic activity of these gold nanoparticles has been proved in the A3 coupling between carbonyl compounds, terminal alkynes and amines to afford propargylamines, and in the cycloisomerization of γ-alkynoic acids to enol lactones. The nanomaterial derived from the PEG-tagged tris-imidazolium bromide provided the best performance and it has been recycled in both reactions (up to four and six runs) taking advantage of its solubility properties.
- Bernardo, Laura,Fernández, Guillem,Pleixats, Roser,Villanueva, Ana
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- Efficient formation of angelica lactones in a vapor-phase conversion of levulinic acid
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Vapor-phase lactonization of levulinic acid to produce angelica lactones, which include α-, β- and γ-form isomers, was performed in fixed-bed down-flow glass reactors over various oxide catalysts. SiO2 and SiO2-Al2O3 showed relatively high catalytic activity. The lactonization of levulinic acid to angelica lactones was found to be an endothermic equilibrium reaction, and the pressure equilibrium constant was calculated to be 0.2?atm at 275?°C. High temperatures and reduced pressures were effective for shifting the equilibrium from levulinic acid to angelica lactones, while the suitable reaction temperature was estimated to be 275?°C because temperatures higher than 275?°C decreased the selectivity to angelica lactones. The highest angelica lactones yield of 87.5% was achieved at a levulinic acid conversion of 95.3% over SiO2 under reduced pressure conditions of ca. 5?kPa at 275?°C. IR, NH3-TPD and TG analyses were performed for characterizing the catalysts used after the reactions together with a silylated SiO2 prepared for studying the active species on SiO2. The silanol groups of SiO2 with weak acidity were proposed to be the active species.
- Sun, Daolai,Takahashi, Yuta,Yamada, Yasuhiro,Sato, Satoshi
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- Single-Molecule Observation of the Intermediates in a Catalytic Cycle
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The development of catalysts benefits from knowledge of the intermediate steps that accelerate the transformations of substrates into products. However, key transient species are often hidden in ensemble measurements. Here, we show that a protein nanoreac
- Ramsay, William J.,Bell, Nicholas A. W.,Qing, Yujia,Bayley, Hagan
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- Ylide-Functionalized Phosphines: Strong Donor Ligands for Homogeneous Catalysis
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Phosphines are important ligands in homogenous catalysis and have been crucial for many advances, such as in cross-coupling, hydrofunctionalization, or hydrogenation reactions. Herein we report the synthesis and application of a novel class of phosphines bearing ylide substituents. These phosphines are easily accessible via different synthetic routes from commercially available starting materials. Owing to the extra donation from the ylide group to the phosphorus center the ligands are unusually electron-rich and can thus function as strong electron donors. The donor capacity surpasses that of commonly used phosphines and carbenes and can easily be tuned by changing the substitution pattern at the ylidic carbon atom. The huge potential of ylide-functionalized phosphines in catalysis is demonstrated by their use in gold catalysis. Excellent performance at low catalyst loadings under mild reaction conditions is thus seen in different types of transformations.
- Scherpf, Thorsten,Schwarz, Christopher,Scharf, Lennart T.,Zur, Jana-Alina,Helbig, Andreas,Gessner, Viktoria H.
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- Dispersed gold nanoparticles supported in the pores of siliceous mesocellular foam: A catalyst for cycloisomerization of alkynoic acids to γ-alkylidene lactones
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A versatile approach for the production of dispersed thiol-stabilized gold nanoparticles in the pores of siliceous mesocellular foam (MCF) is described. The reported method is based on an electrochemical oxidation of a gold surface generating oxidative Au
- Eriksson, Kristofer,Verho, Oscar,Nyholm, Leif,Oscarsson, Sven,B?ckvall, Jan-E.
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- Mercuric triflate·3TMU catalyzed cyclization of ω-alkynoic acids and synthesis of a naturally occurring γ-methylene-γ-lactone
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Hg(OTf)2·3TMU showed efficient catalytic activity for the cyclization of ω-alkynoic acid to give ω-methylene-ω-lactone in excellent yield, and the procedure was efficiently applied for the synthesis of naturally occurring γ-methylene-γ-lactone.
- Imagawa, Hiroshi,Fujikawa, Yukari,Tsuchihiro, Atsushi,Kinoshita, Atsushi,Yoshinaga, Takayuki,Takao, Hiroko,Nishizawa, Mugio
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- Introducing deep eutectic solvents as biorenewable media for Au(i)-catalysed cycloisomerisation of γ-alkynoic acids: An unprecedented catalytic system
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Cycloisomerisation of γ-alkynoic acids into cyclic enol-lactones was conveniently performed, for the first time, in the eutectic mixture 1ChCl/2Urea under standard bench experimental conditions (at room temperature, under air and in the absence of co-cata
- Rodrguez-lvarez, Mara J.,Vidal, Cristian,Dez, Josefina,Garca-lvarez, Joaqun
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- Relative thermodynamic stabilities of γ-methylene-γ-butyrolactone and α-angelicalactone
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The relative thermodynamic stabilities of the title compounds have been determined by chemical equilibration in cyclohexane and dipentyl ether solutions at several temperatures. In each solvent, α-angelicalactone is favored thermodynamically, the values of ΔH(θ) and ΔS(θ) being ca. -8.0 kJ mol-1 and 2 J K-1 mol-1, respectively, for the γ-methylene-γ- butyrolactone → α-angelicalactone isomerization.
- Taskinen, Esko
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- Transition-Metal-Catalyzed Cyclization of Alkynoic Acids to Alkylidene Lactones
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Alkynoic acids I-IV can be effectively cyclized to the corresponding exocyclic enol lactones with a new Rh(I) complex, 2 (4) (cycphos = 1,2-bis(dicyclohexylphosphino)ethane), that we have developed.The high-yield lactonizations can be perfo
- Chan, Dominic M. T.,Marder, Todd B.,Milstein, David,Taylor, Nicholas J.
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- Cu(I) Camphor Coordination Polymers: Synthesis and Study of the Catalytic Activity for Cyclization of 4-Pentyn-1-oic Acid
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The number of CuCl units per camphor ligand in [{CuCl}2L]n was extended to three or four in [{CuCl}3L]n (2) or [{CuCl}4L]n (1). The Hartree-Fock ab initio calculations support the polymeric structure of 1 and 2 that catalyze the cyclization of 4-pentyn-1-
- Fernandes, Tiago A.,Galvo, Adelino M.,Do Rego, Ana M. Botelho,Carvalho, M. Fernanda N. N.
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- Anticancer platinum complexes as non-innocent compounds for catalysis in aqueous media
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An efficient cyclization of alkyne-acids to enol-lactones catalyzed by anticancer platinum(ii) and platinum(iv) compounds is described. These compounds are not only DNA-binding complexes; they can also catalyze reactions in solvents such as acetone, methanol, water or blood plasma.
- Aleman, Jose,Del Solar, Virginia,Navarro-Ranninger, Carmen
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- Redox-Switchable Cycloisomerization of Alkynoic Acids with Napthalenediimide-Derived N-Heterocyclic Carbene Complexes
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Two naphthalene-diimide (NDI) bis-imidazolium salts have been used as N-heterocyclic carbene (NHC) precursors for the preparation of NDI-functionalized complexes of rhodium and iridium of general formula [MCl(NDI-NHC)(COD)] (M=Rh, Ir; NDI-NHC=NDI-function
- Gonell, Sergio,Gutiérrez-Blanco, Ana,Peris, Eduardo,Poyatos, Macarena,Ruiz-Zambrana, César
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- Novel Pd heterogeneous catalysts for cycloisomerisation of acetylenic carboxylic acids
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The Pd-TPPTS complex (TPPTS - trisodium salt of 3,3′,3″- phosphanetriyl benzenesulfonic acid) and PdCl42- salt heterogenised onto Zn2AlNO3 layered double hydroxide (LDH) using an ion-exchange procedure, have bee
- Neau, Florentina,Proteescu, Loredana,Florea, Mihaela,Parvulescu, Vasile I.,Teodorescu, Cristian M.,Apostol, Nicoleta,Toullec, Patrick Y.,Michelet, Veronique
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- New reactions of anticancer-platinum complexes and their intriguing behaviour under various experimental conditions
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The anticancer platinum complexes here described react with organic substrates (such as acids, alkenes, alkynes) and catalyze transformations that can occur in biomolecules which contain unsaturated functions. We have analyzed the role of the platinum complexes in the observed reactions and studied the progress of the detected transformations upon variation of the reaction conditions. The Royal Society of Chemistry 2010.
- Aleman, Jose,Del Solar, Virginia,Cubo, Leticia,Quiroga, Adoracion G.,Navarro Ranninger, Carmen
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- Ruthenium indenylidene and vinylidene complexes bearing Schiff bases: Potential catalysts in enol-ester synthesis
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In an extension of our previous investigations on the ruthenium(II) Schiff-base chemistry, complexes 1, 2, 3a-b and 4a-b were synthesized and tested as catalyst for the nucleophilic addition of carboxylic acids to terminal alkynes. A careful choice of the catalytic system, substrate and carboxylic acid can provide alk-1-en-2-yl esters, alk-1-en-1-yl esters synthesis or enyne dimerization. In this way substituted isopropenol and α-methylenebenzyl formates, (geminal, geminal) dienol diesters were synthesized in one step by direct addition of formic acid or benzoic acid to terminal mono- and di-ynes.
- Opstal, Tom,Verpoort, Francis
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- Intramolecular cyclization of γ-acetylenic acids using dendrimer-encapsulated Pd2+ catalysts
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Polyamine dendrimer-encapsulated Pd2+ catalysts were prepared by complexation of PdCl2 with internal tertiary amino groups of the dendrimer. The fifth-generation Pd2+ dendrimer catalyst showed cooperative catalysis between Pd2+ species and the internal nanocavity consisting of regularly arranged tertiary amino groups to promote the intramolecular cyclization of γ-acetylenic acids efficiently.
- Maeno, Zen,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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Read Online
- N-heterocyclic carbene carboxylate bidentate ligand, bidentate ruthenium complex, preparation method and application of N-heterocyclic carbene carboxylate bidentate ligand and bidentate ruthenium complex in catalyzing carboxylic acid-alkyne addition
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The invention discloses an N-heterocyclic carbene carboxylate bidentate ligand, a bidentate ruthenium complex, a preparation method and application of the N-heterocyclic carbene carboxylate bidentateligand and the bidentate ruthenium complex in catalyzing
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Paragraph 0056-0060
(2020/09/12)
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- A highly active diradical cobalt(iii) catalyst for the cycloisomerization of alkynoic acids
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The first cobalt-catalysed cycloisomerisation of alkynoic acids is reported, thanks to the design of a well-defined diradical cobalt(iii) catalyst, in the absence of any additives. The high efficiency, regioselectivity and chemoselectivity are comparable to those of noble metal-based systems. The unique reactivity might be attributed to second coordination sphere effects.
- Leconte, Nicolas,Du Moulinet D'Hardemare, Amaury,Philouze, Christian,Thomas, Fabrice
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supporting information
p. 8241 - 8244
(2018/07/29)
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- Pyrene-Connected Tetraimidazolylidene Complexes of Iridium and Rhodium. Structural Features and Catalytic Applications
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A pyrene-connected tetra-imidazolium salt has been prepared starting from commercially available 1,3,6,8-tetrabromopyrene, and used as tetra-NHC precursor in the preparation of tetranuclear Rh(I) and Ir(I) complexes. The tetra-NHC ligand displays axial ch
- Gutiérrez-Blanco, Ana,Peris, Eduardo,Poyatos, Macarena
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p. 4070 - 4076
(2018/11/23)
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- Stable yet reactive cationic gold catalysts with carbon based counterions
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L-Au-[TsC(CN)2] are new cationic gold catalysts with a carbon based counterion, which are widely applicable for gold catalyzed reactions. For reactions which need highly reactive gold catalysts, a Lewis acid co-catalyst can be added to increase
- Zeng, Xiaojun,Liu, Shiwen,Xu, Bo
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p. 77830 - 77833
(2018/06/22)
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- Palladium NNC Pincer Complex as an Efficient Catalyst for the Cycloisomerization of Alkynoic Acids
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A two-step (nucleophilic substitution/palladation by oxidative addition) sequence provides a high-yielding access to a non-symmetrical palladium NNC pincer complex. A number of terminal and internal alkynoic acids with different substitution patterns at the α- and β-positions are regio- and diastereoselectively cycloisomerized to the corresponding exocyclic enol lactones in the presence of exceedingly low amounts of the latter palladium complex, so that unprecedented turnover numbers and frequencies ranging from 1,000,000 to 700,000 and from 41,667 to 9722 h?1, respectively, are achieved. The optimized protocol, based on the use of a catalytic amount of triethylamine as base, allows an easy real-time monitoring of the reaction by NMR spectroscopy. Several pieces of evidence in favor of the direct participation of the above pincer complex as the catalyst of the reaction have been gathered from kinetic and poisoning experiments. (Figure presented.).
- Conde, Nerea,SanMartin, Raul,Herrero, María Teresa,Domínguez, Esther
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p. 3283 - 3292
(2016/10/21)
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- Gold(I)-Catalysed Cyclisation of Alkynoic Acids: Towards an Efficient and Eco-Friendly Synthesis of γ-, δ- and ?-Lactones
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The improved synthesis of γ-, δ- and ?-lactones using a dinuclear N-heterocyclic carbene (NHC)-gold(I) catalyst is reported. This solvent-free process provides access to γ- and δ-lactones in high regio- and stereoselectivity. Reactions were performed at l
- Gasperini, Danila,Maggi, Lorenzo,Dupuy, Stéphanie,Veenboer, Richard M. P.,Cordes, David B.,Slawin, Alexandra M. Z.,Nolan, Steven P.
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supporting information
p. 3857 - 3862
(2016/12/16)
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- Catalytic activity assessment of [RuCl2 (p-cymene) (PTA)] in the synthesis of enol esters
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The addition of carboxylic acids onto 1-hexyne was catalyzed by [RuCl2 (p-cymene) (PTA)] complex to give enol esters. Accordingly, the Markovnikov addition-type product was selectively obtained. The microwave-assisted reactions at 160 °C confir
- Musengimana, Eric,Fatakanwa, Claver
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p. 253 - 259
(2016/01/09)
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- Efficient Synthesis of Unsaturated δ- and ε-Lactones/Lactams by Catalytic Cycloisomerization: When Pt Outperforms Pd
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Platinum pincer complexes featuring an SCS indenediide backbone have been prepared and evaluated in the catalytic cycloisomerization of alkynoic acids and N-tosyl alkynylamides. One of the platinum complexes significantly outperforms its palladium analogue for the formation of 6- and 7-membered rings. The catalytic system takes advantage of the alkynophilicity of Pt and of the non-innocent character of the indenediide framework. Like for Pd, the catalytic performance is significantly improved by using an H-bond donor additive such as pyrogallol. For the first time, a large variety of ω-unsaturated δ- and ε-lactones/lactams could be prepared with high selectivities and in very good yields. (Figure presented.) .
- Ke, Diandian,Espinosa, Noel ángel,Mallet-Ladeira, Sonia,Monot, Julien,Martin-Vaca, Blanca,Bourissou, Didier
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supporting information
p. 2324 - 2331
(2016/07/29)
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- Smaller, faster, better: Modular synthesis of unsymmetrical ammonium salt-tagged NHC-gold(i) complexes and their application as recyclable catalysts in water
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Facile access towards a small library of unsymmetrical ammonium salt-tagged N-heterocyclic carbene gold(i) complexes is described, and their application as recyclable catalysts in cyclization reactions of acetylenic carboxylic acids and amides to lactones and lactams, respectively, in aqueous media is demonstrated. Catalyst 1ab was applied in the synthesis of 2-epi-clausemarine A (16).
- Belger, Katrin,Krause, Norbert
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supporting information
p. 8556 - 8560
(2015/08/06)
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- Metalloenzyme-mimicking supramolecular catalyst for highly active and selective intramolecular alkyne carboxylation
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Creation of synthetic catalysts with enzyme-like behavior is challenging despite strong interest in such systems. Extraction of tetrachloroaurate into the hydrophilic core of an interfacially cross-linked reverse micelle (ICRM) produced an artificial "metalloenzyme" with highly unusual catalytic properties. The ICRM pulled the substrate toward the catalytic metal, which converted it efficiently to the product that was rapidly ejected. These features enabled greatly reduced catalyst loading (30-100 times lower than typical levels used in literature examples), constant high reaction rate throughout the course of the reaction, lack of the hydrolyzed side product, and substrate selectivity unobserved in conventional gold catalysts.
- Lee, Li-Chen,Zhao, Yan
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supporting information
p. 5579 - 5582
(2014/05/06)
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- A highly efficient and broadly applicable cationic gold catalyst
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Gold catalysts capable of promoting reactions at low-level loadings under mild conditions are the exception rather than the norm. We examined reactions where the regeneration of cationic gold catalyst (e.g., protodeauration) was the turnover limiting stag
- Malhotra, Deepika,Mashuta, Mark S.,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 4456 - 4459
(2014/05/06)
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- Cycloisomerization of acetylenic acids to γ-alkylidene lactones using a palladium(II) catalyst supported on amino-functionalized siliceous mesocellular foam
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Cycloisomerization of various γ-acetylenic acids to their corresponding γ-alkylidene lactones by the use of a heterogeneous Pd(II) catalyst supported on amino-functionalized siliceous mesocellular foam is described. Substrates containing terminal as well
- Nagendiran, Anuja,Verho, Oscar,Haller, Clemence,Johnston, Eric V.,Baeckvall, Jan-E.
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p. 1399 - 1405
(2014/03/21)
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- Enhanced reactivity in Homogeneous Gold catalysis through Hydrogen bonding
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Additives that are good hydrogen-bond acceptors increase the efficiency of gold-catalyzed reactions in those instances where protodeauration is the rate-determining step. The efficiency of additives capable of hydrogen-bonding-assisted protodeauration correlated with their standing in a scale of hydrogen bonding basicity (measured by pKBHX). All additives used in the study are commercially available.
- Wang, Weibo,Kumar, Manish,Hammond, Gerald B.,Xu, Bo
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p. 636 - 639
(2014/04/03)
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- Efficient generation and increased reactivity in cationic gold via Bronsted acid or lewis acid assisted activation of an imidogold precatalyst
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Bronsted or Lewis acid assisted activation of an imidogold precatalyst (L-Au-Pht, Pht = phthalimide) offers a superior way to generate cationic gold compared with the commonly used silver-based system. It is also broadly applicable for most common gold-catalyzed reactions. For reactions that require milder conditions, milder acids can be used for optimized efficiency.
- Han, Junbin,Shimizu, Naoto,Lu, Zhichao,Amii, Hideki,Hammond, Gerald B.,Xu, Bo
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supporting information
p. 3500 - 3503
(2014/07/21)
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- Cooperative catalysis: Large rate enhancements with bimetallic rhodium complexes
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A large increase in reaction rate was observed for the catalyzed mono- and dihydroalkoxylation of alkynes when structurally constrained bimetallic Rh(I) catalysts with imidazolyl-imine ligands were compared to their monometallic analogues. The "cooperative" enhancement was vastly improved by restricting the conformational freedom of the bimetallic structure and minimizing the intermetallic Rh···Rh distance.
- Choy, Sandra W. S.,Page, Michael J.,Bhadbhade, Mohan,Messerle, Barbara A.
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p. 4726 - 4729
(2013/09/24)
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- Flow microwave technology and microreactors in synthesis
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A bespoke microwave reactor with a glass containment cell has been developed for performing continuous flow reactions under microwave heating. The prototype unit has been evaluated using a series of standard organic chemical transformations enabling scale-up of these chemical processes. As part of the development, a carbon-doped PTFE reactor insert was utilized to allow the heating of poorly absorbing reaction media, increasing the range of solvents and scope of reactions that can be performed in the device.
- Baxendale, Ian R.,Hornung, Christian,Ley, Steven V.,De Mata Munoz Molina, Juan,Wikstroem, Anders
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p. 131 - 144
(2013/03/28)
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- Cycloisomerization versus hydration reactions in aqueous media: A Au(III)-NHC catalyst that makes the difference
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A novel water-soluble Au(III)-NHC complex has been synthesized and successfully applied in the intramolecular cyclization of γ-alkynoic acids into enol-lactones under biphasic toluene/water conditions, thus representing a rare example of an active and sel
- Tomas-Mendivil, Eder,Toullec, Patrick Y.,Diez, Josefina,Conejero, Salvador,Michelet, Veronique,Cadierno, Victorio
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scheme or table
p. 2520 - 2523
(2012/07/14)
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- Rhodium(i) complexes bearing N-donor ligands: Catalytic activity towards intramolecular cyclization of alkynoic acids and ligand lability
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The structures of rhodium(i) complexes bearing tris(pyrazol-1-yl)toluidine (tpt) and tris(N-methylimidazol-2-yl)methanol (tim) ligands were examined in the solid state using single crystal X-ray diffraction, and in the solution state using variable temperature NMR spectroscopy. The solid state structures of the rhodium(i) tpt and rhodium(i) tim complexes showed that the ligands are bound to the rhodium(i) centre in the κ2 binding mode, rather than the κ3 binding mode. In the solution state, rhodium(i) complexes bearing the tpt ligand undergo fluxional behaviour at room temperature, which was attributed to rotation of the toluidine substituent about the C-C bond or the equilibrium between κ2 and κ3 binding modes. At low temperatures, rhodium(i) complexes bearing the tpt ligand adopted the κ2 binding mode, consistent with the coordination mode in the solid state structures. The efficiency of the complexes as catalysts for the intramolecular hydroalkoxylation of 4-pentynoic acid and 5-hexaynoic acid to form the corresponding lactone was established. The presence of the third unbound N-donor was shown to reduce the catalytic efficiency of the complexes with tridentate ligands when compared to their counterparts bearing bidentate ligands, due to either the steric hindrance or competitive binding of the third N-donor with the substrate during the catalytic cycle.
- Man, Bradley Y.-W.,Bhadbhade, Mohan,Messerle, Barbara A.
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supporting information; experimental part
p. 1730 - 1739
(2011/10/02)
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- Acetylacetonato(phosphane)iridium complexes: Synthesis and catalytic activity in the cyclization of alkynoic acids
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The iridium complex [Ir(acac)(η2-coe)2] (1) has been easily prepared by the addition of Tl(acac) to a suspension of [Ir(μ-Cl)(η2-coe)2]2 in hexane. Complex 1 has been characterized fully including an
- Geier, Michael J.,Vogels, Christopher M.,Decken, Andreas,Westcott, Stephen A.
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experimental part
p. 4602 - 4610
(2011/02/27)
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- Cyclization of alkynoic acids with gold catalysts: a surprising dichotomy between AuI and AuIII
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ω-Acetylenic acids, substituted or not at their acetylenic end, could be efficiently cyclized to γ- or δ-alkylidene lactones in the presence of AuCl and K2CO3. In contrast AuCl3 led to lactone dimers, probably through cycl
- Harkat, Hassina,Dembelé, Albert Yénimégué,Weibel, Jean-Marc,Blanc, Aurélien,Pale, Patrick
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experimental part
p. 1871 - 1879
(2009/06/28)
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