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Benjamin List - One of the best experts on this subject based on the ideXlab platform.
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the catalytic Asymmetric mukaiyama michael reaction of silyl ketene acetals with α β unsaturated methyl esters
Angewandte Chemie, 2018Co-Authors: Tim Gatzenmeier, Philip S J Kaib, Julia B Lingnau, Richard Goddard, Benjamin ListAbstract:α,β-Unsaturated esters are readily available but challenging substrates to activate in Asymmetric Catalysis. We now describe an efficient, general, and highly enantioselective Mukaiyama-Michael reaction of silyl ketene acetals with α,β-unsaturated methyl esters that is catalyzed by a silylium imidodiphosphorimidate (IDPi) Lewis acid.
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Asymmetric Catalysis via Cyclic, Aliphatic Oxocarbenium Ions
Journal of the American Chemical Society, 2017Co-Authors: Philip S J Kaib, Benjamin ListAbstract:A direct enantioselective synthesis of substituted oxygen heterocycles from lactol acetates and enolsilanes has been realized using a highly reactive and confined imidodiphosphorimidate (IDPi) catalyst. Various chiral oxygen heterocycles, including tetrahydrofurans, tetrahydropyrans, oxepanes, chromans, and dihydrobenzofurans, were obtained in excellent enantioselectivities by reacting the corresponding lactol acetates with diverse enol silanes. Mechanistic studies suggest the reaction to proceed via a nonstabilized, aliphatic, cyclic oxocarbenium ion intermediate paired with the confined chiral counteranion.
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Asymmetric Catalysis via Cyclic, Aliphatic Oxocarbenium Ions
2017Co-Authors: Sunggi Lee, Philip S J Kaib, Benjamin ListAbstract:A direct enantioselective synthesis of substituted oxygen heterocycles from lactol acetates and enolsilanes has been realized using a highly reactive and confined imidodiphosphorimidate (IDPi) catalyst. Various chiral oxygen heterocycles, including tetrahydrofurans, tetrahydropyrans, oxepanes, chromans, and dihydrobenzofurans, were obtained in excellent enantioselectivities by reacting the corresponding lactol acetates with diverse enol silanes. Mechanistic studies suggest the reaction to proceed via a nonstabilized, aliphatic, cyclic oxocarbenium ion intermediate paired with the confined chiral counteranion
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Asymmetric Catalysis with co2 the direct α allylation of ketones
Angewandte Chemie, 2016Co-Authors: Gabriele Pupo, Roberta Properzi, Benjamin ListAbstract:: Quaternary stereocenters are found in numerous bioactive molecules. The Tsuji-Trost reaction has proven to be a powerful C-C bond forming process, and, at least in principle, should be well suited to access quaternary stereocenters via the α-allylation of ketones. However, while indirect approaches are known, the direct, catalytic Asymmetric α-allylation of branched ketones has been elusive until today. By combining "enol Catalysis" with the use of CO2 as a formal catalyst for Asymmetric Catalysis, we have now developed a solution to this problem: we report a direct, highly enantioselective and highly atom-economic Tsuji-Trost allylation of branched ketones with allylic alcohol. Our reaction delivers products bearing quaternary stereocenters with high enantioselectivity and water as the sole by-product. We expect our methodology to be of utility in Asymmetric Catalysis and inspire the design of other highly atom-economic transformations.
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phosphoric acid based heterodimers in Asymmetric Catalysis
Synlett, 2016Co-Authors: Mattia R Monaco, Gabriele Pupo, Benjamin ListAbstract:Chiral phosphoric acid diesters arguably constitute the most exploited class of catalysts in Asymmetric Bronsted acid Catalysis. Despite being highly investigated for their acidic properties, these compounds display an amphoteric nature, which has instead been considerably overlooked. The potential of this dichotomous polarity has recently been disclosed and applied to the development of novel reaction modes in organoCatalysis. In this account, we present our recent advances in this area, focusing on the establishment of heterodimeric interactions toward the nucleophilic activation of carboxylic acids, thiocarboxylic acids and ketones (via their enols) in Asymmetric transformations. 1 Introduction 2 Discovery of Heterodimeric Self-Assemblies 3 Activation of Carboxylic Acids 3.1 The Enantioselective Carboxylysis of Aziridines 3.2 An Asymmetric Hydrolysis of Epoxides 4 Activation of Thiocarboxylic Acids 5 Enol Catalysis 5.1 Asymmetric Michael Addition 5.2 Asymmetric α-Amination 5.3 Asymmetric α-Allylation 6 Concluding Remarks
Yong Cui - One of the best experts on this subject based on the ideXlab platform.
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supramolecular coordination cages for Asymmetric Catalysis
Chemistry: A European Journal, 2019Co-Authors: Chunxia Tan, Dandan Chu, Xianhui Tang, Yan Liu, Weimin Xuan, Yong CuiAbstract:Inspired by the high efficiency and specificity of enzymes in living systems, the development of artificial catalysts intrinsic to the key features of enzyme has emerged as an active field. Recent advances in supramolecular chemistry have shown that supramolecular coordination cages, built from non-covalent coordination bonds, offer a diverse platform for enzyme mimics. Their inherent confined cavity, analogous to the binding pocket of an enzyme, and the facile tunability of building blocks are essential for substrate recognition, transition-state stabilization, and product release. In particular, the combination of chirality with supramolecular coordination cages will undoubtedly create an Asymmetric microenvironment for promoting enantioselective transformation, thus providing not only a way to make synthetically useful Asymmetric catalysts, but also a model to gain a better understanding for the fundamental principles of enzymatic Catalysis in a chiral environment. The focus here is on recent progress of supramolecular coordination cages for Asymmetric Catalysis, and based on how supramolecular coordination cages function as reaction vessels, three approaches have been demonstrated. The aim of this review is to offer researchers general guidance and insight into the rational design of sophisticated cage containers for Asymmetric Catalysis.
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sixteen isostructural phosphonate metal organic frameworks with controlled lewis acidity and chemical stability for Asymmetric Catalysis
Nature Communications, 2017Co-Authors: Xu Chen, Yan Liu, Xing Han, Yongwu Peng, Xiaochao Lin, Yong CuiAbstract:Heterogeneous catalysts typically lack the specific steric control and rational electronic tuning required for precise Asymmetric Catalysis. Here we demonstrate that a phosphonate metal–organic framework (MOF) platform that is robust enough to accommodate up to 16 different metal clusters, allowing for systematic tuning of Lewis acidity, catalytic activity and enantioselectivity. A total of 16 chiral porous MOFs, with the framework formula [M3 L 2(solvent)2] that have the same channel structures but different surface-isolated Lewis acid metal sites, are prepared from a single phosphono-carboxylate ligand of 1,1′-biphenol and 16 different metal ions. The phosphonate MOFs possessing tert-butyl-coated channels exhibited high thermal stability and good tolerances to boiling water, weak acid and base. The MOFs provide a versatile family of heterogeneous catalysts for Asymmetric allylboration, propargylation, Friedel–Crafts alkylation and sulfoxidation with good to high enantioselectivity. In contrast, the homogeneous catalyst systems cannot catalyze the test reactions enantioselectively. Asymmetric synthesis predominantly falls within the realm of homogeneous Catalysis. Here, the authors synthesized 16 chiral metal–organic frameworks differing in the nature of the transition metal and demonstrate their excellent stability, catalytic activity and recyclability in a number of enantioselective reactions.
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multivariate chiral covalent organic frameworks with controlled crystallinity and stability for Asymmetric Catalysis
Journal of the American Chemical Society, 2017Co-Authors: Jie Zhang, Yan Liu, Xing Han, Yong CuiAbstract:The modular construction of covalent organic frameworks (COFs) provides a convenient platform for designing high-performance functional materials, but the synthetic control over their chirality has been relatively barely studied. Here we report a multivariate strategy to prepare chiral COFs (CCOFs) with controlled crystallinity and stability for Asymmetric Catalysis. By crystallizing mixtures of triamines with and without chiral organocatalysts and with a dialdehyde, a family of two- and three-component 2D porous CCOFs that adopt two different stacking modes is prepared. The organocatalysts are periodically appended on the channel walls, and their contents, which can be synthetically tuned using a three-component condensation system, greatly affect the chemical stability and crystallinity of CCOFs. Specially, the ternary CCOFs displayed relatively high crystallinity and stability compared with the binary CCOFs. Under harsh conditions, the ternary CCOFs can serve as efficient heterogeneous catalysts for an...
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Multivariate Chiral Covalent Organic Frameworks with Controlled Crystallinity and Stability for Asymmetric Catalysis
2017Co-Authors: Jie Zhang, Yan Liu, Xing Han, Yong CuiAbstract:The modular construction of covalent organic frameworks (COFs) provides a convenient platform for designing high-performance functional materials, but the synthetic control over their chirality has been relatively barely studied. Here we report a multivariate strategy to prepare chiral COFs (CCOFs) with controlled crystallinity and stability for Asymmetric Catalysis. By crystallizing mixtures of triamines with and without chiral organocatalysts and with a dialdehyde, a family of two- and three-component 2D porous CCOFs that adopt two different stacking modes is prepared. The organocatalysts are periodically appended on the channel walls, and their contents, which can be synthetically tuned using a three-component condensation system, greatly affect the chemical stability and crystallinity of CCOFs. Specially, the ternary CCOFs displayed relatively high crystallinity and stability compared with the binary CCOFs. Under harsh conditions, the ternary CCOFs can serve as efficient heterogeneous catalysts for an Asymmetric aminooxylation reaction, an aldol reaction, and the Diels–Alder reaction, with the stereoselectivity and diastereoselectivity rivaling or surpassing the homogeneous analogues. This work not only opens up a new synthetic route toward CCOFs, but also provides tunable control of COF crystallintity and stability and, in turn, the properties
Masakatsu Shibasaki - One of the best experts on this subject based on the ideXlab platform.
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nucleophilic and electrophilic activation of non heteroaromatic amides in atom economical Asymmetric Catalysis
Chemistry: A European Journal, 2016Co-Authors: Naoya Kumagai, Masakatsu ShibasakiAbstract:Recent advances in catalytic Asymmetric carbon–carbon bond-forming reactions of non-heteroaromatic amide substrates are highlighted. Among carbonyl compounds, amides have received limited attention in catalytic Asymmetric transformations mainly owing to their lower reactivity. Amides are reluctant to form enolates for nucleophilic addition, and α,β-unsaturated amides exhibit diminished electrophilicity at the β-carbon. Recent advances in Asymmetric Catalysis rendered these amides amenable to enantioselective reactions with perfect atom economy, producing synthetically useful chiral building blocks. This Minireview summarizes recent developments in the field.
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recent advances in cooperative bimetallic Asymmetric Catalysis dinuclear schiff base complexes
Chemical Communications, 2014Co-Authors: Shigeki Matsunaga, Masakatsu ShibasakiAbstract:Cooperative Catalysis has proven to be a powerful strategy for realizing high reactivity and selectivity in Asymmetric transformations. A variety of cooperative Asymmetric catalysts have been developed over the last two decades. In this feature article, recent advances from our research on cooperative Asymmetric Catalysis, focusing on dinuclear Schiff base Catalysis, are described. Design of dinuclear Schiff base catalysts and their applications in several Asymmetric C–C and C–N bond-forming reactions under simple proton transfer conditions with perfect atom-economy are discussed in detail.
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Managing highly coordinative substrates in Asymmetric Catalysis: a catalytic Asymmetric amination with a lanthanum-based ternary catalyst.
Journal of the American Chemical Society, 2009Co-Authors: Tomoyuki Mashiko, Naoya Kumagai, Masakatsu ShibasakiAbstract:Full details of a catalytic Asymmetric amination with a lanthanum/amide-based ligand catalyst system are described. A catalyst comprising La(NO3)3•6H2O, (R)-3a and H-d-Val-OtBu was identified to promote the catalytic Asymmetric amination of nonprotected succinimide derivative 1 with as little as 1 mol % catalyst loading. Mechanistic studies by various spectroscopic analyses and several control and kinetic experiments suggested that the catalyst components were in equilibrium between the associated and dissociated forms, and that the reaction likely proceeded through a La(NO3)3•6H2O/(R)-3a/H-d-Val-OtBu ternary complex. This catalyst system was also effective for Asymmetric amination of N-nonsubstituted α-alkoxycarbonyl amides 7, hitherto unprecedented substrates in Asymmetric Catalysis, probably due to their attenuated reactivity and difficult stereocontrol, affording the amination products in up to >99% yield and >99% ee. The high catalytic performance and enantiocontrol of the reaction with highly coordi...
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linking structural dynamics and functional diversity in Asymmetric Catalysis
ChemInform, 2009Co-Authors: Akihiro Nojiri, Naoya Kumagai, Masakatsu ShibasakiAbstract:Proteins, the functional molecules in biological systems, are sophisticated chemical devices that have evolved over billions of years. Their function is intimately related to their three-dimensional structure and elegantly regulated by conformational changes through allosteric regulators and a number of reversible or unidirectional post-translational modifications. This functional diversification in response to external stimuli allows for an orderly and timely progression of intra- and extracellular events. In contrast, enantioselective catalysts generally exhibit limited conformational flexibility and thereby exert a single specific function. Exploiting the features of conformationally flexible Asymmetric ligands and the variable coordination patterns of rare earth metals, we demonstrate dynamic structural and functional changes of a catalyst in Asymmetric Catalysis, leading to two distinct reaction outcomes in a single flask.
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power of cooperativity lewis acid lewis base bifunctional Asymmetric Catalysis
Synlett, 2005Co-Authors: Motomu Kanai, Nobuki Kato, Eiko Ichikawa, Masakatsu ShibasakiAbstract:The concept of bifunctional Asymmetric Catalysis is very powerful for designing new enantioselective catalysts. We describe our investigation starting with the development of a BINOL-derived Lewis acid-Lewis base bifunctional Asymmetric catalyst for cyanosilylation of aldehydes. The initial establishment of the concept was followed by the development of new sugar-derived catalysts that promote general catalytic enantioselective cyanosilylation of ketones. We also describe the catalytic enantioselective Reissert reaction of pyridine derivatives and Strecker reaction of ketoimines as recent advances in this field.
Eric N Jacobsen - One of the best experts on this subject based on the ideXlab platform.
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Asymmetric Catalysis by chiral hydrogen-bond donors
Angewandte Chemie - International Edition, 2006Co-Authors: Mark S. Taylor, Eric N JacobsenAbstract:Hydrogen bonding is responsible for the structure of much of the world around us. The unusual and complex properties of bulk water, the ability of proteins to fold into stable three-dimensional structures, the fidelity of DNA base pairing, and the binding of ligands to receptors are among the manifestations of this ubiquitous noncovalent interaction. In addition to its primacy as a structural determinant, hydrogen bonding plays a crucial functional role in Catalysis. Hydrogen bonding to an electrophile serves to decrease the electron density of this species, activating it toward nucleophilic attack. This principle is employed frequently by Nature's catalysts, enzymes, for the acceleration of a wide range of chemical processes. Recently, organic chemists have begun to appreciate the tremendous potential offered by hydrogen bonding as a mechanism for electrophile activation in small-molecule, synthetic catalyst systems. In particular, chiral hydrogen-bond donors have emerged as a broadly applicable class of catalysts for enantioselective synthesis. This review documents these advances, emphasizing the structural and mechanistic features that contribute to high enantioselectivity in hydrogen-bond-mediated catalytic processes.
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Asymmetric Catalysis of epoxide ring opening reactions
Accounts of Chemical Research, 2000Co-Authors: Eric N JacobsenAbstract:The discovery of the metal salen-catalyzed Asymmetric ring-opening (ARO) of epoxides is chronicled. A screening approach was adopted for the identification of catalysts for the addition of TMSN3 to meso-epoxides, and the chiral (salen)CrN3 complex was identified as optimal. Kinetic and structural studies served to elucidate the mechanism of Catalysis, which involves cooperative activation of both epoxide and azide by two different metal centers. Covalently linked bimetallic complexes were constructed on the basis of this insight, and shown to catalyze the ARO with identical enantioselectivity but 1−2 orders of magnitude greater reactivity than the monomeric analogues. Extraordinarily high selectivity is observed in the kinetic resolution of terminal epoxides using the (salen)CrN3/TMSN3 system. A search for a practical method for the kinetic resolution reaction led to the discovery of highly enantiomer-selective hydrolytic ring-opening using the corresponding (salen)CoIII catalyst. This system displays ext...
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comprehensive Asymmetric Catalysis
1999Co-Authors: Eric N Jacobsen, Andreas Pfaltz, 尚 山本Abstract:5.2. R.L. Halterman: Hydrogenation of Non-Functionalized Carbon-Carbon Double Bonds .- 6.4. T. Ohkuma, R. Noyori: Hydroboration of Carbonyl Groups .- 20.1. A. Bayer: Latest Developments in the Asymmetric Dihydroxylation Process .- 20.2. A. Bayer: Aminohydroxylation of Carbon-Carbon Double Bonds .- 24. J.-F. Paquin, M. Lautens: Allylic Substitution Reactions .- 27. A. Yanagisawa: Allylation of C=O .- 31.1. K. Tomioka: Conjugate Addition of Organometallics to Activated Olefins .- 34.2. A. Yanagisawa: Protonation of Enolates
Wei Wang - One of the best experts on this subject based on the ideXlab platform.
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imidazolium based organic inorganic hybrid silica as a functional platform dramatically boosts chiral organometallics performance in Asymmetric Catalysis
Chemcatchem, 2013Co-Authors: Daquan Xia, Tanyu Cheng, Wei Xiao, Ketang Liu, Zhaoliang Wang, Guohua Liu, Wei WangAbstract:Phase-transfer featured, imidazolium-based, organic-inorganic hybrid silica represents a novel functionalized platform with particularly attractive features in Asymmetric Catalysis. Herein, we report a chiral organorhodium-functionalized heterogeneous catalyst. As demonstrated in the studies, it displays comparable or higher catalytic activity and enantioselectivity than its homogeneous counterpart in Asymmetric transformations. The superior catalytic performance is attributed to the synergistic effect of the salient imidazolium phase-transfer character and the confined chiral organorhodium catalytic nature in addition to the merits of mesoporous silica. Furthermore, it is more robust than other silica-derived heterogeneous systems and can be conveniently recovered and reused at least 10 times without loss of its catalytic efficiency. These features render the catalyst particularly attractive in practice of organic synthesis. The outcomes from the study clearly show that the strategy described here offers a general approach to immobilization of chiral ligand-derived silane onto the phase-transfer featured imidazolium-based organic-inorganic hybrid silica materials with significant improving catalyst efficiency.
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hydrogen bond mediated Asymmetric Catalysis
Chemistry-an Asian Journal, 2008Co-Authors: Wei WangAbstract:: The utilization of hydrogen bonding as an activation force has become a powerful tool in Asymmetric organoCatalysis. Significant advances have been made in the recent past in this emerging field. Due to space constraints, this Focus Review summarizes only the key aspects with an emphasis on Catalysis based on chiral ureas and thioureas, diols, and phosphoric acids. The examples provided neatly demonstrate that chiral ureas and thioureas, diols, and phosphoric acids display effective and unique activation modes of Catalysis for a broad spectrum of Asymmetric organic transformations, including single-step and multiple-step cascade reactions. These functionalities, which have the ability to afford efficient H-bond activation of electrophiles including C=O, C=N, aziridines, and epoxides, have established their status as "privileged" functional groups in the design of organocatalysts.
