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Literatura académica sobre el tema "Salen chiraux"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Salen chiraux"

Gualandi, Andrea, Francesco Calogero, Simone Potenti y Pier Giorgio Cozzi. "Al(Salen) Metal Complexes in Stereoselective Catalysis". Molecules 24, n.º 9 (2 de mayo de 2019): 1716. http://dx.doi.org/10.3390/molecules24091716.

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Salen ligands are a class of Schiff bases simply obtained through condensation of two molecules of a hydroxyl-substituted aryl aldehyde with an achiral or chiral diamine. The prototype salen, or N,N′-bis(salicylidene)ethylenediamine has a long history, as it was first reported in 1889, and immediately, some of its metal complexes were also described. Now, the salen ligands are a class of N,N,O,O tetradentate Schiff bases capable of coordinating many metal ions. The geometry and the stereogenic group inserted in the diamine backbone or aryl aldehyde backbone have been utilized in the past to efficiently transmit chiral information in a variety of different reactions. In this review we will summarize the important and recent achievements obtained in stereocontrolled reactions in which Al(salen) metal complexes are employed. Several other reviews devoted to the general applications and synthesis of chromium and other metal salens have already been published.

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Adão, Pedro, Mannar R. Maurya, Umesh Kumar, Fernando Avecilla, Rui T. Henriques, Maxim L. Kusnetsov, João Costa Pessoa y Isabel Correia. "Vanadium-salen and -salan complexes: Characterization and application in oxygen-transfer reactions". Pure and Applied Chemistry 81, n.º 7 (30 de junio de 2009): 1279–96. http://dx.doi.org/10.1351/pac-con-08-09-07.

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Salen complexes are a versatile and standard system in oxidation catalysis. Their reduced derivatives, called salan, share their versatility but are still widely unexplored. We report the synthesis of a group of new vanadium-salen and -salan complexes, their characterization and application in the oxidation of simple organic molecules with H2O2. The ligands are derived from pyridoxal and chiral diamines (1,2-diaminocyclohexane and 1,2-diphenylethylenediamine) and were easily obtained in high yields. The VIV complexes were prepared and characterized in the solid state (Fourier transform infrared, FTIR, and magnetic properties) and in solution by spectroscopic techniques: UV–vis, circular dichroism (CD), electron paramagnetic resonance (EPR), and 51V NMR, which provide information on the coordination geometry. Single crystals suitable for X-ray diffraction studies were obtained from solutions containing the VIV-pyr(S,S-chan) complex: [VVO{pyr(S,S-chen)}]2(μ-O)2·2(CH3)2NCHO, where the ligand is the “half” Schiff base formed by pyridoxal and 1S,2S-diaminocyclohexane. The dinuclear species shows a OVV(μ-O)2VVO unit with tridentate ligands and two μ-oxo bridges. The VIV complexes of the salan-type ligands oxidize in organic solvents to a VV species, and the process was studied by spectroscopic techniques. The complexes were tested as catalysts in the oxidation of styrene, cyclohexene, and cumene with H2O2 as oxidant. Overall, the V-salan complexes show higher activity than the parent V-salen complexes and are an alternative ligand system for oxidation catalysis.

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Zuo, Shengli, Shuxiang Zheng, Jianjun Liu y Ang Zuo. "Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides". Beilstein Journal of Organic Chemistry 18 (10 de octubre de 2022): 1416–23. http://dx.doi.org/10.3762/bjoc.18.147.

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In this paper, we report the mechanochemical synthesis of unsymmetrical salens using grinding and ball milling technologies, respectively, both of which were afforded in good yield. The chelating effect of the unsymmetrical salens with zinc, copper, and cobalt was studied and the chiral Co–salen complex 2f was obtained in 98% yield. Hydrolytic kinetic resolution (HKR) of epichlorohydrin with water catalyzed by complex 2f (0.5 mol %) was explored and resulted in 98% ee, suggesting complex 2f could serve as an enantioselective catalyst for the asymmetric ring opening of terminal epoxides by phenols. A library of α-aryloxy alcohols 3 was thereafter synthesized in good yield and high ee using 2f via the phenolic KR of epichlorohydrin.

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Karukurichi, Kannan R., Xiang Fei, Robert A. Swyka, Sylvain Broussy, Weijun Shen, Sangeeta Dey, Sandip K. Roy y David B. Berkowitz. "Mini-ISES identifies promising carbafructopyranose-based salens for asymmetric catalysis: Tuning ligand shape via the anomeric effect". Science Advances 1, n.º 6 (julio de 2015): e1500066. http://dx.doi.org/10.1126/sciadv.1500066.

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This study introduces new methods of screening for and tuning chiral space and in so doing identifies a promising set of chiral ligands for asymmetric synthesis. The carbafructopyranosyl-1,2-diamine(s) and salens constructed therefrom are particularly compelling. It is shown that by removing the native anomeric effect in this ligand family, one can tune chiral ligand shape and improve chiral bias. This concept is demonstrated by a combination of (i) x-ray crystallographic structure determination, (ii) assessment of catalytic performance, and (iii) consideration of the anomeric effect and its underlying dipolar basis. The title ligands were identified by a new mini version of the in situ enzymatic screening (ISES) procedure through which catalyst-ligand combinations are screened in parallel, and information on relative rate and enantioselectivity is obtained in real time, without the need to quench reactions or draw aliquots. Mini-ISES brings the technique into the nanomole regime (200 to 350 nmol catalyst/20 μl organic volume) commensurate with emerging trends in reaction development/process chemistry. The best-performing β-d-carbafructopyranosyl-1,2-diamine–derived salen ligand discovered here outperforms the best known organometallic and enzymatic catalysts for the hydrolytic kinetic resolution of 3-phenylpropylene oxide, one of several substrates examined for which the ligand is “matched.” This ligand scaffold defines a new swath of chiral space, and anomeric effect tunability defines a new concept in shaping that chiral space. Both this ligand set and the anomeric shape-tuning concept are expected to find broad application, given the value of chiral 1,2-diamines and salens constructed from these in asymmetric catalysis.

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Chaudhary, Pooja, Geeta Devi Yadav, Krishna K. Damodaran y Surendra Singh. "Synthesis of new chiral Mn(iii)–salen complexes as recoverable and reusable homogeneous catalysts for the asymmetric epoxidation of styrenes and chromenes". New Journal of Chemistry 46, n.º 3 (2022): 1308–18. http://dx.doi.org/10.1039/d1nj04758b.

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Soundararajan, Karthikeyan, Helen Ratna Monica Jeyarajan, Raju Subimol Kamarajapurathu y Karthik Krishna Kumar Ayyanoth. "Facile and innovative catalytic protocol for intramolecular Friedel–Crafts cyclization of Morita–Baylis–Hillman adducts: Synergistic combination of chiral (salen)chromium(III)/BF3·OEt2 catalysis". Beilstein Journal of Organic Chemistry 17 (26 de agosto de 2021): 2186–93. http://dx.doi.org/10.3762/bjoc.17.140.

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The chiral (salen)Cr(III)/BF3·OEt2 catalytic combination was found to be an effective catalyst for intramolecular Friedel–Crafts cyclization of electron-deficient Morita–Baylis–Hillman adducts. In presence of mild reaction conditions the chiral (salen)Cr(III)/BF3·OEt2 complex affords 2-substituted-1H-indenes from unique substrates of Morita–Baylis–Hillman adducts via an easy operating practical procedure.

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Ikbal, Sk Asif, Yoko Sakata y Shigehisa Akine. "A chiral spirobifluorene-based bis(salen) zinc(ii) receptor towards highly enantioselective binding of chiral carboxylates". Dalton Transactions 50, n.º 12 (2021): 4119–23. http://dx.doi.org/10.1039/d1dt00218j.

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Jia, Yihong, Asma A. Alothman, Rui Liang, Xiaoyong Li, Weiyi Ouyang, Xiangdong Wang, Yong Wu et al. "Oligomeric (Salen)Mn(III) Complexes Featuring Tartrate Linkers Immobilized over Layered Double Hydroxide for Catalytically Asymmetric Epoxidation of Unfunctionalized Olefins". Materials 13, n.º 21 (29 de octubre de 2020): 4860. http://dx.doi.org/10.3390/ma13214860.

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A series of oligomeric (salen)Mn(III) complexes featuring tartrate linkers were prepared and immobilized over layered double hydroxide, and then used as catalysts for asymmetric epoxidation of unfunctionalized olefins. Comprehensive characterizations including 1H NMR, FT-IR, UV-Vis, elemental analysis, GPC, and ICP-AES were used to illustrate structures of oligomeric (salen)Mn(III) complexes, while powdered XRD, nitrogen physisorption, together with XPS studies provided further details to detect structures of heterogeneous catalysts. Interestingly, scanning electron microscopy found an interesting morphology change during modification of layered supporting material. Catalytic experiments indicated that configuration of major epoxide products was determined by salen chirality more than that of tartrate linker, but enantioselectivity (e.e. values) could be enhanced when tartrate and salen showed identical chiral configurations. Furthermore, the (R,R)-salen moieties linked with (R,R)-tartrate spacers usually offered higher enantioselectivity compared to other combinations. Lastly, Zn(II)/Al(III) layered double hydroxide played as a rigid supporting material in catalysis, showing positive chiral induction and high recycling potential in catalytic reactions.

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Pappalardo, Andrea, Francesco P. Ballistreri, Rosa Maria Toscano, Maria Assunta Chiacchio, Laura Legnani, Giovanni Grazioso, Lucia Veltri y Giuseppe Trusso Sfrazzetto. "Alkene Epoxidations Mediated by Mn-Salen Macrocyclic Catalysts". Catalysts 11, n.º 4 (2 de abril de 2021): 465. http://dx.doi.org/10.3390/catal11040465.

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Three new chiral Mn macrocycle catalysts containing 20 or 40 atoms in the macrocycle were synthetized and tested in the enantioselective epoxidation of cis-β-ethyl-styrene and 1,2-dihydronathalene. The effect of the presence of a binaphtol (BINOL) compound in the catalyst backbone has been evaluated, including by Density Functional Theory (DFT) calculations.

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Kim, Sung Soo. "Asymmetric cyanohydrin synthesis from aldehydes and ketones using chiral metal (salen) complex as catalyst". Pure and Applied Chemistry 78, n.º 5 (1 de enero de 2006): 977–83. http://dx.doi.org/10.1351/pac200678050977.

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Más fuentes

Tesis sobre el tema "Salen chiraux"

Zulauf, Anaïs. "Nouveaux complexes salen chiraux polymérisés pour la catalyse asymétrique hétérogène". Paris 11, 2009. http://www.theses.fr/2009PA112170.

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Nous avons développé une méthode originale d’insolubilisation de complexes de type salen chiraux basée sur leur polymérisation par oxydation électrochimique. Ces nouveaux complexes ont été préparés puis électropolymérisés grâce à l’introduction de substituants thiophènes sur les positions 5,5’ du salen. Les polymères insolubles obtenus ont été testés en tant que catalyseurs asymétriques hétérogènes dans différentes réactions de formation de liaisons carbone-carbone ou carbone-hétéroatome catalysé par des complexes de chrome notamment les réactions d��hétéro Diels-Alder, de Henry, d’ouverture d’époxydes et d’addition de diméthylzinc. Ces nouveaux catalyseurs ont conduit à la synthèse des composés ciblés avec de très bons rendements et excès énantiomériques. Ils ont été recyclés jusqu’à 20 fois sans perte ni d’activité ni d’énantiosélectivité prouvant ainsi leur efficacité pour le transfert de chiralité. Deux procédures de recyclage très originales rarement décrites dans la bibliographie ont été testées. L’une consiste à modifier le substrat d’une même réaction à chaque cycle pour une procédure multi-substrats, l’autre consiste à changer de réaction à chaque cycle (procédure multi-réactions). Cette dernière nous a permis de démontrer la robustesse de nos catalyseurs hétérogènes. Nous avons également envisagé la synthèse d’analogues obtenus par polycondensation pour laquelle un mélange d’oligomères cycliques, de type « Calix-Salen » a été obtenus. Ces nouveaux catalyseurs ont permis d’améliorer l’énantiosélectivité des réactions ciblées notamment pour l’ouverture des époxydes et confirmé l’importance de la morphologie des matériaux et des conditions de polymérisation
The aim of this work was to develop an original methodology to insolubilize chiral salen type chromium complexes based on an oxidative electrochemical polymerization. New complexes were prepared and succesfully electropolymerized thanks to the introduction of thiophen substituents on the 5,5’-positions of the salen moiety. The insoluble polymers obtained as powder by this electrochemical procedure were tested as heterogeneous asymmetric catalysts to promote the formation of different carbon-carbon or carbon-heteroatom bonds by reactions such as hetero Diels-Alder reactions, Henry reactions, ring opening of epoxides and dimethylzinc additions. The targeted products were synthesized with good yields and enantiomeric excesses. It could be recycled more than 20 times without any loss of activity or enantioselectivity. The results proved an efficient transfer of chirality from the catalysts to the products. We also implement original recycling procedures with the same catalyst batch rarely described in the litterature. One involves a change of the substrate structure at each run (multi-substrate procedure), the other one consists in varying the reaction at each recycling run (multi-reaction procedure). This last methodology demonstrates the robustness of the heterogeneous catalyst but also highlighted some mechanistic considerations for transformations. The synthesis of analogous polymeric salen structures was also performed by polycondensation. A mixture of cyclic oligomers of type « calixsalen » was isolated. Corresponding chromium complexes induced an improved enantioselectivity especially in the ring opening of epoxides and confirmed thus the importance of the morphology of the polymers towards their efficiency

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Zidelmal, Nacim. "SILIPOLYSALEN : étude du greffage par polymérisation contrôlée de complexes de salen sur silicium pour une application en catalyse asymétrique hétérogène". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS058.

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Les complexes métalliques chiraux de type salen sont connus pour la diversité de leur utilisation en catalyse conduisant à la préparation de nombreux synthons énantio-enrichis. Conformément au concept de chimie verte, l'un des principaux objectifs est d'établir une procédure efficace pour la récupération et la réutilisation de ces catalyseurs. Dans ce contexte, l'objectif de ce travail est de fonctionnaliser la surface du silicium par greffage covalent de ces catalyseurs par polymérisation contrôlée notamment la polymérisation radicalaire par transfert d’atome (ATRP) pour leur récupération et leur réutilisation. Ainsi, des copolymères de styrène contenant 5 à 50 mol% d’un comonomère salen dissymétrique ont été synthétisés par ATRP en solution. Le caractère contrôlé des polymérisations n’est obtenu que lorsque l’incorporation du comonomère salen est inférieure ou égale à 10 mol %.Après complexation au cobalt, les polymères correspondants se sont révélés capables de réaliser une activation coopérative efficace, conduisant au produit ciblé avec des rendements et des sélectivités élevés en tant que catalyseurs dans la réaction de dédoublement cinétique hydrolytique de l’épibromohydrine.Nous avons également réalisé la polymérisation du styrène sur la surface de silicium par ATRP après greffage de l’amorceur. Plusieurs méthodes de greffage de l’amorceur ont été utilisées soit d’une manière directe à partir de la surface hydrogénée, soit indirecte à partir d’une surface acide ou ester. Le styrène a été ensuite efficacement polymérisé en masse avec succès de façon contrôlée sur le silicium, avec des épaisseurs de couche comprise entre 9 et 29 nm déterminées par ellipsométrie et microscopie à force atomique
Chiral metal complexes of salen type are known for their efficient catalytic activity leading to the preparation of enantioselective enriched synthons. In accordance with the concept of green chemistry, one of the main challenge is to establish a procedure for the recovery and reuse of these catalysts. In this context, the objective of this work is to functionalize the silicon surface by grafting these catalysts by controlled polymerization especially by Atom Transfer Radical Polymerization (ATRP) to facilitate their recovery and reuse.Thus, styrene copolymers containing 5 to 50 mol % of an disymmetric salen comonomer were synthesized by ATRP in solution. The controlled nature of the polymerizations is obtained only when the incorporation of the salen comonomer is less than or equal to 10%.After complexation with cobalt, these complexes are shown to be capable of effective cooperative activation, leading to the targeted product with high yields and selectivities as catalysts in Hydrolytic Kinetic Resolution (HKR) of epibromohydrin.Constantio Constantini fratre imperatoris, matreque Galla.We also reported the polymerization of styrene on the silicon surface by ATRP after grafting of the initiator. Several methods of initiator grafting have been used either directly from the hydrogenated surface or indirectly from an acid or ester surface. Styrene has been successfully mass polymerized in a controlled manner on silicon with thicknesses of 9-29 nm of the layer obtained by ellipsometry and Atomic Force Microscopy

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Hong, Xiang. "Nouveaux catalyseurs hétérogènes chiraux pour le dédoublement cinétique hydrolytique des époxydesTERMINAUX". Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00770302.

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L'objectif de ce travail étaient le développement de catalyseurs hétérogènes efficaces pour promouvoir des réactions asymétriques, en utilisant la polymérisation oxydante ou la formation de polymères de coordination. De nouveaux complexes de salen Co(III) chiraux modifiés par des groupements aromatiques sur les position 5, 5' ont été préparés et testés dans le dédoublement cinétique hydrolytique (HKR) des époxydes terminaux en conditions homogènes. Ces complexes ont été ensuite engagés dans les polymérisations oxydantes électrochimiques ou chimiques, et une stratégie de copolymérisation a fourni des polymères chiraux très efficaces et stables pour catalyser l'HKR dans des conditions hétérogènes. Nous avons alors cherché à préparer un catalyseur capable de catalyser deux réactions en cascade, en copolymérisant deux complexes de salen portant des métaux différents. Pendant ces études, les complexes de salen Mn ont révélé leur participation active à la réaction d'HKR des époxydes terminaux catalysée par les complexes de salen Co(III), en augmentant l'excès énantiomérique du produit de façon significative. Les études mécanistiques ont été ensuite réalisées pour tenter de comprendre le rôle des complexes de Mn dans cette réaction. De plus, des complexes de salen fonctionnalisés par le groupement pyridine ou le groupement de type acide isophtalique ont été synthétisés. Ces complexes ont été utilisés pour préparer de nouveaux réseaux de polymères de coordination poreux chiraux (collaboration avec l'équipe LCI de l'ICMMO et l'Institut Lavoisier à Versailles), qui sont ensuite testés comme catalyseurs hétérogènes dans la réaction de Henry asymétrique et la réaction d'HKR.

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Voituriez, Arnaud. "Nouveaux ligands soufrés chiraux pour la catalyse asymétrique homogène : vers l'électrocatalyse asymétrique hétérogène". Paris 11, 2004. http://www.theses.fr/2004PA112132.

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L'objectif est la synthèse par électropolymérisation d'un polymère organique conducteur (POC) chiral, chélatant des métaux de transition, pour une utilisation en électrocatalyse asymétrique hétérogène. Cette approche électrochimique devrait remplacer un co-réducteur ou un co-oxydant, nécessaire en quantité sur-stœchiométrique dans certaines réactions catalytiques. Nous avons préparé dix ligands chiraux, de structure dibenzothiophène et benzothiophène-oxazolines. Les tests en catalyse asymétrique dans la réaction de Tsuji-Trost ont permis d'obtenir, avec le DBT-BOx-iPr, 77% ee pour 90% de rendement. Des monomères simples de type T-DBT-T ont été synthétisés et polymérisés par voltampérométrie cyclique, démontrant une bonne stabilité à la surface de l'électrode. Mais les tests en catalyse homogène dans la réaction de Nozaki-Hiyama (NH), réaction ciblée pour l'électrocatalyse asymétrique, en présence du DBT-BOx-iPr, ont donné des résultats décevants. Nous avons alors synthétisé des ligands thiophènes-salen chiraux, qui dans les conditions de la réaction de NH, ont conduit à des résultats plus encourageants (50 % de rendement et 32 % d'ee). L'électropolymérisation des complexes métalliques correspondants a permis l'obtention de POC stables. Cependant, la mise au point de la version électrochimique de la réaction de NH n'a pas abouti. Parallèlement, et dans l'optique de réaliser la réaction de NH en catalyse hétérogène, nous avons synthétisé des polymères de type calixsalen. Nous avons réalisé trois tests catalytiques successifs, ce qui constitue, à notre connaissance, le premier exemple de catalyse asymétrique hétérogène dans la réaction de NH catalytique en chrome
The aim of this work is the synthesis of asymmetric conductor organic polymers, as metal chelates, for heterogeneous asymmetric electrocatalysis. Furthermore, the electrochemistry has to replace a co-reducer or a co-oxydant, which are often required in over-stoechiometric quantities in some catalytic reactions. We have prepared ten new chiral ligands, with dibenzothiophene (DBT) and benzothiophene-oxazoline structures. These new ligands were tested in the Tsuji-Trost reaction. The sulfur-monooxazoline (DBT-MOx and BT-MOx) ligands are efficient for this transformation, but the best results were obtained with a bisoxazoline, the DBT-BOx-iPr (90% yield and 77% ee). Some new monomers Thiophene-DBT-Thiophene were synthesized and polymerized by cyclic voltammetry, showing a good stability at the electrode surface. However, the catalytic homogeneous tests in the Nozaki-Hiyama (NH) reaction, the target reaction for the asymmetric electrocatalysis, with enantiopur dibenzothiophene type ligands, gave disappointing results. We have thus synthesized new asymmetric thiophene-salen ligands, which led to interesting results in the NH reaction (32% ee and 50% yield). The electropolymerization of the corresponding metal-complexes allowed the formation of stable conductors organics polymers. However, all attempts to perform electrochemically driven NH reaction failed. In parallel, and to realize the NH reaction by heterogeneous catalysis, we synthesized new polymers of calixsalen-type. We performed three successive tests, which constitute, to the best of our knowledge, the first asymmetric heterogeneous NH reaction, with catalytic quantities of chromium

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Dandachi, Hiba. "Nouveaux Complexes Oligomères Cycliques de Salens Chiraux pour la Catalyse Asymétrique". Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS106/document.

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Les ligands de type salen constituent la pierre angulaire des travaux décrits dans cette thèse. L’attention particulière portée aux complexes chiraux correspondants est due à leur utilisation comme catalyseurs énantiosélectives versatiles pour promouvoir une large gamme de réactions d’intérêt. Dans le contexte de la catalyse asymétrique hétérogène, nous nous focalisons plus particulièrement sur l’élaboration de catalyseurs polymères cycliques de salens chiraux, appelés complexes calixsalens. Ainsi, nous avons mis au point une voie d’accès directe aux calixsalens de cobalt (III) par polycondensation. Ces complexes testés en tant que catalyseurs dans le dédoublement cinétique dynamique hydrolytique de l’épibromohydrine peuvent être facilement récupérés par simple filtration du milieu réactionnel et réutilisés dans une nouvelle transformation. Ces ligands cycliques permettent donc la préparation de complexes homobimétalliques capables de réaliser une double activation efficace de l’époxyde et de l’eau, conduisant au produit ciblé avec des rendements et des sélectivités élevés.Nous avons également rapporté l’utilisation de ces mêmes calixsalens de cobalt (III) en présences des complexes analogues de manganèse (III) dans la réaction d’hydrolyse des époxydes méso. Ce système de catalyse hétérobimétallique s’est révélé encore plus sélectif que le système homobimétallique impliquant les catalyseurs de cobalt seuls.Suite à ces résultats, nous avons tenté de préparer des complexes de salens hétérobimétalliques, dans lesquels deux métaux différents sont présents sur le même macrocycle. Pour ce faire, nous avons choisi d’explorer la chimie click pour coupler des complexes salens porteurs de différents métaux, modifiés les uns par des fonctions alcynes, les autres par des groupements azotures
This thesis work takes place in the broad context of salen chemistry. A special attention is given to corresponding chiral complexes used as versatile enantioselective catalysts for a wide range of reactions of interest. In the context of heterogeneous asymmetric catalysis, we focus specifically on the development of polymeric, cyclic, chiral salen catalysts, named calixsalen complexes. Thus, we have developed an easy access to calixsalen cobalt (III) complexes by a facile polycondensation route. These calixsalens were used as catalysts to promote the dynamic hydrolytic kinetic resolution of epibromohydrin. They are easily recovered from the reaction mixture by a simple filtration. These cyclic complexes allowed the formation of homobimetallic species responsible for an efficient dual activation of both the epoxide and water, delivering the targeted product in both high yield and selectivity.We have also reported the use of a combination of cobalt and manganese calixsalen complexes in the hydrolysis of meso epoxydes. This dual heterobimetallic system proved to be even more selective than the homobimetallic one, in which cobalt complexes were only engaged. Based on these results, we have attempted preparing heterobimetallic salen complexes, wherein two different metals should be closely associated into the same macrocycle. Towards this aim, we explored click chemistry to couple alkyne- and azide-functionalized monomeric salen complexes coordinated to two different metals

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Tucker, S. C. "Towards novel ligands for catalytic asymmetric oxidation". Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242038.

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Zhang, Weiqiang. "Synthesis of novel chiral pyrrolidine-type (salen)Mn(III) complexes". Thesis, Swansea University, 2006. https://cronfa.swan.ac.uk/Record/cronfa42403.

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The thesis reports the total syntheses of new chiral pyrrolidine-type salen ligands 5.4 and their corresponding Mn(III) complexes 5.5. The salen ligands were synthesized by condensation of tras-(3R,4R)-diaminopyrrolidine (3.12) or trans-(3R,4R)-1-benzyl-3,4-diaminopyrrolidine (3.10) with two equivalents of (R)-3-formyl-2-hydroxy-2'-phenyl-1,1'-binaphthalene [(R)-4.9]. The salen ligands were transformed to their corresponding Mn(III) complexes following a general procedure. The catalytic performances of the synthesized (salen)Mn(III) complexes in asymmetric epoxidation of 1,2-dihydronaphthalene were tested. In chapter 1, a review of asymmetric epoxidation of alkenes is given. Emphasis is placed on the development and some of the important designs of chiral salen ligands and their corresponding (salen)Mn(III) complexes. In chapter 2, the nature of the research project is outlined. In chapter 3, the syntheses of trans-(3R,4R)-diaminopyrrolidine trihydrochloride salt (3.9), trans-(3R,4R)-1-benzyl-3,4-diaminopyrrolidine (3.10) and its trihydrochloride salt (3.11) are reported. These compounds were prepared from (2R,3R)-(-i-)-tartaric acid via multi-step syntheses. Extensive studies on optimization of these transformations are reported. Chapter 4 records the synthesis of (R)-3-formyl-2-hydroxy-2'-phenyl-1,1'-binaphthalene [(R)-4.9] from 2-naphthol via a seven-step synthetic procedure. Extensive studies on these transformations are described, especially on the oxidative coupling of 2-naphthol and on the optical resolution of racemic 2,2'-dihydroxy-1,1'-binaphthalene. In chapter 5, the preparations of salen ligands 5.4 and their corresponding Mn(III) complexes 5.5 are reported. The applications of synthesized Mn(III) complexes in asymmetric epoxidation of 1,2-dihydronaphthalene were carried out. In chapter 6, an overall conclusion of the work is given.

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Olcay, Elmali. "Asymmetric Syntheses Of Various Novel Chiral Ligands With Norbornene Backbone: The Use Of Chiral Catalyst In Asymmetric Reactions". Phd thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12606192/index.pdf.

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The synthetic strategy of this study mainly depends upon the asymmetric desymmetrization of meso norbornene type an anhydride. Asymmetric desymmetrization was achieved by using chinchona alkaloids under kinetically controlled conditions. The resultant mono ester carboxylic acid was epimerized to trans configuration. Subsequent esterification followed by lithium aluminum hydride reduction afforded the first chiral diol ligand with 98 % ee. Transformation of diol to corresponding trans diamine was achieved via Mitsunobu-Gabriel combination. The resultant diamine was first transformed into salen type ligand with 3,5-di-tert-butyl-2-hydroxybenzaldehyde. Throughout this process, no racemization was observed and all the ligands tested in asymmetric reactions have 98 % ee value. The second part of the thesis involves the asymmetric test reactions of the chiral ligands to check the effectiveness of them. The first testing method was diethylzinc addition to benzaldehyde. The ligands showed moderate effectiveness. The salen type ligand was tested in asymmetric epoxidation and aziridination reactions and it showed good effectiveness. Another applied method was desymmetrization of meso 2-cyclohexene-3,4-diol in which 2-(diphenylphosphino)benzoic acid attached trans-diol and trans-diamine type ligands were tested. Since norbornene type strained bicyclic systems are available in ring opening methathesis polymerization (ROMP) reactions, trans-diamine was subjected to ROMP to get an enlarged macromolecular system

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Hernandez, Sanchez Dalyanne N. "Synthesis of Chiral Salen-type Ligands for Iridium Catalysts Used in C-H Bond Insertion Reactions". Kent State University Honors College / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1620475657966529.

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Wingstrand, Erica. "New Methods for Chiral Cyanohydrin Synthesis". Doctoral thesis, KTH, Kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10205.

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This thesis deals with method development in asymmetric catalysis and specifically syntheses of enantioenriched O-functionalized cyanohydrins. The first part describes the development of a method for the synthesis of O‑alkoxycarbonylated and O-acylated cyanohydrins. Ethyl cyanoformate and acyl cyanides were added to aldehydes in a reaction catalyzed by a chiral dimeric Ti-salen complex together with a tertiary amine. High yields and enantioselectivities were in most cases obtained. Mechanistic studies were performed and a reaction mechanism was proposed. The second part describes a method in which the undesired minor enantiomer in a Lewis acid–Lewis base-catalyzed acylcyanation is continuously recycled into prochiral starting material. Close to enantiopure O‑acylated cyanohydrins were obtained in high yields. The third part deals with asymmetric acylcyanations of ketones. Acetyl cyanide was found to add to α‑ketoesters in a reaction catalyzed by a chiral Lewis base. Yields up to 77% and 82% ee were obtained. The final part describes an enzymatic method for high-throughput analysis of O‑acylated cyanohydrins. The enantiomeric excess and conversion were determined for products obtained from a number of aromatic and aliphatic aldehydes.
QC 20100818

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Capítulos de libros sobre el tema "Salen chiraux"

Zhang, Wen-Zhen y Xiao-Bing Lu. "Chiral Salen Complexes". En Privileged Chiral Ligands and Catalysts, 257–93. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2011. http://dx.doi.org/10.1002/9783527635207.ch7.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of manganese(III) complex with chiral salen-type ligand". En Magnetic Properties of Paramagnetic Compounds, 1358–59. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49202-4_666.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of manganese(III) complex with chiral salen-type ligand". En Magnetic Properties of Paramagnetic Compounds, 1360–61. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49202-4_667.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of iron(III) complex with chiral salen-type ligand". En Magnetic Properties of Paramagnetic Compounds, 253–54. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53971-2_130.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of copper(II) complex with chiral salen-type ligand". En Magnetic Properties of Paramagnetic Compounds, 467–68. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-53974-3_244.

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Lee, Kwang Yeon, Young Hee Lee, Chang Kyo Shin y Geon Joong Kim. "Chiral (Salen) Complexes Encapsulated in Mesoporous ZSM-5 as an Optical Active Catalyst for Asymmetric Phenolic Ring Opening of Terminal Epoxides". En Solid State Phenomena, 1809–12. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/3-908451-31-0.1809.

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Ollevier, T. "2.11 Iron-Based Chiral Lewis Acid Catalysts in Organic Synthesis". En Base-Metal Catalysis 2. Stuttgart: Georg Thieme Verlag KG, 2023. http://dx.doi.org/10.1055/sos-sd-239-00149.

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AbstractVarious synthetic applications of iron-based Lewis acid complexes are presented through their most noteworthy and groundbreaking applications in asymmetric catalysis. The iron Lewis acids are organized according to their structure, and then their reactivity. It has been reported that various chiral iron Lewis acids can be used in a broad range of synthetic transformations. Diverse categories of chiral ligands are used in asymmetric catalysis using chiral iron complexes, including N,N′-dioxides, bipyridines, oxazolines, Schiff bases, salen/salan-type structures, and aminopyridines.

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Wong, Y. S. "Chiral Manganese(III)–salen Catalyzed Epoxidation". En 1,3-Dienes, 1. Georg Thieme Verlag KG, 2009. http://dx.doi.org/10.1055/sos-sd-046-00403.

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Garbaccio, R. M. y S. E. Wolkenberg. "Chiral Aluminum–Salen Complex Catalyzed Strecker Synthesis". En Three Carbon-Heteroatom Bonds: Acid Halides; Carboxylic Acids and Acid Salts, 1. Georg Thieme Verlag KG, 2007. http://dx.doi.org/10.1055/sos-sd-020-01085.

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Vicens, L., A. Palone y M. Costas. "2.12 Asymmetric C—H Oxidation with Biologically Inspired Manganese and Iron Catalysts". En Base-Metal Catalysis 2. Stuttgart: Georg Thieme Verlag KG, 2023. http://dx.doi.org/10.1055/sos-sd-239-00318.

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AbstractEnantioselective oxidation of aliphatic C—H bonds is the most straightforward and atom-economical approach to prepare chiral oxygenated hydrocarbon skeletons, which are ubiquitous in molecules of biological and industrial relevance. In Nature, this reaction is carried out by metalloenzymes with high levels of efficiency and selectivity. Due to the exquisite performance of enzymatic systems, their active site has served as inspiration for the exploration of artificial catalysts, such as those based on porphyrins or coordination compounds with tetradentate salen- or bis-amine-bis-pyridine-type ligands. Reviewed herein are the latest advances in enantioselective C—H oxidations using biologically inspired iron and manganese complexes.

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