Synthesis And Application Of New Chiral Ligands For Enantioselectivity Tuning In Transition Metal Catalysis
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Synthesis And Application Of New Chiral Ligands For Enantioselectivity Tuning In Transition Metal Catalysis
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Author : Fanji Kong
language : en
Publisher:
Release Date : 2017
Synthesis And Application Of New Chiral Ligands For Enantioselectivity Tuning In Transition Metal Catalysis written by Fanji Kong and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with Chirality categories.
A set of five new C3-symmetric phosphites were synthesized and tested in palladium-catalyzed asymmetric Suzuki coupling. The observed reactivity and selectivity were dependent upon several factors. One of the phosphites was able to achieve some of the highest levels of enantioselectivity in asymmetric Suzuki couplings with specific substrates. Different hypotheses have been made for understanding the ligand effects and reaction selectivities, and those hypotheses were tested via various methods including DOSY NMR experiments, X-ray crystallography, and correlation of catalyst selectivity with Tolman cone angles. Although only modest enantioselectivities were observed in most reactions, the ability to synthesis these phosphites in only three steps on gram scales and to readily tune their properties by simple modification of the binaphthyl 2́-substituents makes them promising candidates for determining structure-selectivity relationships in asymmetric transition metal catalysis, in which phosphites have been previously shown to be successful. A series of novel chiral oxazoline-based carbodicarbene ligands was targeted for synthesis. Unfortunately, the chosen synthetic route could not be completed due to unwanted reactivity of the oxazoline ring. However, a new and efficient route for Pd-catalyzed direct amination of aryl halides with oxazoline amine was developed and optimized during these studies. Chiral binaphthyl based Pd(II) ADC complexes with different substituent groups have been synthesized and tested in asymmetric Suzuki coupling reactions. Although only low enantioselectivities were observed in Suzuki coupling, this represents a new class of chiral metal-ADC catalysts that could be tested in further catalytic.
Design Of New Monodentate Ligands For Regioselectivity And Enantioselectivity Tuning In Late Transition Metal Catalysis
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Author : Aaron A. Ruch
language : en
Publisher:
Release Date : 2016
Design Of New Monodentate Ligands For Regioselectivity And Enantioselectivity Tuning In Late Transition Metal Catalysis written by Aaron A. Ruch and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Catalysis categories.
The ability of gold(I) to activate many types of unsaturated bonds toward nucleophilic attack was not widely recognized until the early 2000s. One major challenge in gold catalysis is the control over regioselectivity when there are two or more possible products as a result of complicated mechanistic pathways. It is well know that the choice of ligand can have dramatic effects on which pathway is being followed but very rarely are the reasons for this selectivity understood. The synthesis of new acyclic diaminocarbenes was developed and a study of the ligand effects on the regioselectivity of a gold-catalyzed domino enyne cyclization hydroarylation reaction and a Nazarov cyclization was undertaken. New chiral acyclic diaminocarbenes were also developed and tested along side new C3-symmetric phosphite ligands in an asymmetric intramolecular hydroamination of allenes. Structure activity correlations were developed for the potential use in further rational ligand design. The synthesis of 6a,7-dihydro-5-amino-dibenzo[c,g]chromene derivatives via a gold-catalyzed domino reaction of alkynylbenzaldehydes in the presence of secondary amines was developed. These were sent to be screened for biological activity.
Chiral Phosphorous Based Ligands In Earth Abundant Transition Metal Catalysis
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Author : Junliang Zhang
language : en
Publisher: Elsevier
Release Date : 2023-05-27
Chiral Phosphorous Based Ligands In Earth Abundant Transition Metal Catalysis written by Junliang Zhang and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-05-27 with Science categories.
Chiral Phosphorous Based Ligands in Earth-Abundant Transition Metal Catalysis summarizes the most significant progress in the field of chiral phosphine ligand chemistry and a broad range of earth-abundant transition metal/chiral phosphine ligand-catalyzed enantioselective transformations. The book provides an authoritative and in-depth understanding of important topics about asymmetric catalysis based on earth-abundant transition metals/chiral phosphine ligands, making it ideal for organic chemistry researchers working in the field of asymmetric catalysis, synthetic methodologies and total synthesis.The development of new chiral phosphine ligands to achieve precise stereo control in many earth-abundant transition metal-catalyzed reactions is a very important field in organic synthesis, materials science and medicinal chemistry. The asymmetric synthesis promoted by transition metal/chiral phosphine ligands provides one of the most ideal ways to produce valuable optically active chemicals. Includes a discussion of state-of-the-art asymmetric organic reactions mediated by earth-abundant transition metals and chiral phosphine ligands Features the progress and the prospect of chiral phosphine ligands in asymmetric transition metal catalysis Covers the asymmetric reactivity modes of earth-abundant transition metals and phosphine ligands
Rational Design Of New Chiral Ligands For Transition Metal Catalyzed Asymmetric Synthesis
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Author : David John O'Neill
language : en
Publisher:
Release Date : 1999
Rational Design Of New Chiral Ligands For Transition Metal Catalyzed Asymmetric Synthesis written by David John O'Neill and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with categories.
Enantioselective C C Bond Forming Reactions
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Author :
language : en
Publisher: Elsevier
Release Date : 2023-12-01
Enantioselective C C Bond Forming Reactions written by and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-12-01 with Science categories.
Enantioselective C-C Bond Forming Reactions: From Metal Complex-, Organo-, and Bio-catalyzed Perspectives, Volume 73 in the Advances in Catalysis series, highlights new advances in the field, with this new volume presenting interesting chapters on topics such as An introduction to Chirality, Metal-catalyzed stereoselective C-C-bond forming reactions, Enantioselective C-C bond forming reactions promoted by organocatalysts based on unnatural amino acid derivatives, Enantioselective C-C bond formation in complex multicatalytic system, Gold-based multicatalytic systems for enantioselective C-C Bond forming reactions, Novel enzymatic tools for C-C bond formation through the development of new-to-nature biocatalysis, and more. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in Advances in Catalysis serials Updated release includes the latest information in the field
Synthesis Of New Chiral Ligands And Their Application In Catalytic Enantioselective Reactions
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Author : Kedar Shankar Karmarkar
language : en
Publisher:
Release Date : 1996
Synthesis Of New Chiral Ligands And Their Application In Catalytic Enantioselective Reactions written by Kedar Shankar Karmarkar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with categories.
Asymmetric Organocatalysis Combined With Metal Catalysis
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Author : Bruce A. Arndtsen
language : en
Publisher: Springer Nature
Release Date : 2020-04-24
Asymmetric Organocatalysis Combined With Metal Catalysis written by Bruce A. Arndtsen and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-04-24 with Science categories.
The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience.Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.The chapter "Enamine/Transition Metal Combined Catalysis: Catalytic Transformations Involving Organometallic Electrophilic Intermediates" is available open access under a CC BY 4.0 License via link.springer.com.
Chiral Ligands
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Author : Montserrat Diéguez
language : en
Publisher: CRC Press
Release Date : 2021-05-12
Chiral Ligands written by Montserrat Diéguez and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-05-12 with Medical categories.
Many new drugs on the market are chiral compounds, that is, they can exist in two non-superimposable mirror-image forms. Asymmetric catalysis encompasses a large variety of processes for obtaining such compounds. The performance of the catalyst in those processes largely depends on the ligand that makes up the catalyst. This book describes the most relevant ligand libraries for some key processes, including an overview of the state of art and the key mechanistic aspects that favor a high catalytic performance. Key Features: The book presents historical content from the time of discovery for each family of ligands. Provides a description of the synthetic route and the ligand library's application in various catalytic asymmetric reactions Suitable as supplementary reading for courses targeting the design, synthesis and application of chiral catalysts, asymmetric catalysis and sustainable production Edited by a distinguished scientist in the field, the book has a diverse audience including research groups in homogeneous catalysis, particularly asymmetric transformations
Transition Metal Catalyzed Enantioselective Allylic Substitution In Organic Synthesis
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Author : Uli Kazmaier
language : en
Publisher: Springer
Release Date : 2011-10-28
Transition Metal Catalyzed Enantioselective Allylic Substitution In Organic Synthesis written by Uli Kazmaier and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-10-28 with Science categories.
Giovanni Poli, Guillaume Prestat, Frédéric Liron, Claire Kammerer-Pentier: Selectivity in Palladium Catalyzed Allylic Substitution.- Jonatan Kleimark and Per-Ola Norrby: Computational Insights into Palladium-mediated Allylic Substitution Reactions.- Ludovic Milhau, Patrick J. Guiry: Palladium-catalyzed enantioselective allylic substitution.- Wen-Bo Liu, Ji-Bao Xia, Shu-Li You: Iridium-Catalyzed Asymmetric Allylic Substitutions.- Christina Moberg: Molybdenum- and Tungsten-Catalyzed Enantioselective Allylic Substitutions.- Jean-Baptiste Langlois, Alexandre Alexakis: Copper-catalyzed enantioselective allylic substitution.- Jeanne-Marie Begouin, Johannes E. M. N. Klein, Daniel Weickmann, B. Plietker: Allylic Substitutions Catalyzed by Miscellaneous Metals.- Barry M. Trost, Matthew L. Crawley: Enantioselective Allylic Substitutions in Natural Product Synthesis.
Explorations On Transition Metal Catalyzed Enantioselective Cyclization Reactions And Applications Of Thiourea Ligands
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Author : Min Yang
language : en
Publisher: Open Dissertation Press
Release Date : 2017-01-27
Explorations On Transition Metal Catalyzed Enantioselective Cyclization Reactions And Applications Of Thiourea Ligands written by Min Yang and has been published by Open Dissertation Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-27 with categories.
This dissertation, "Explorations on Transition Metal-catalyzed Enantioselective Cyclization Reactions and Applications of Thiourea Ligands" by Min, Yang, 楊敏, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled EXPLORATIONS ON TRANSITION METAL- CATALYZED ENANTIOSELECTIVE CYCLIZATION REACTIONS AND APPLICATIONS OF THIOUREA LIGANDS submitted by Yang Min for the Degree of Doctor of Philosophy at The University of Hong Kong in November 2005 Transition metal-catalyzed carbon-carbon bond formation and carbon- heteroatom bond formation are powerful tools in synthetic chemistry, and have been widely applied in the construction of cyclic compounds. The aim of this project is to develop enantioselective cyclization reactions by the application of transition metals and chiral ligands. A chiral Lewis acid-promoted highly enantioselective intramolecular carbonyl ene cyclization reaction of unsaturated α-keto esters has been developed (Scheme 1). In the presence of chiral Lewis acids such as [Sc((R, R)-Ph- pybox)](OTf) and [Cu((S, S)-Ph-box)](OTf), unsaturated α-keto esters (1.1c-f) 3 2 underwent carbonyl ene reactions smoothly under mild conditions to give cis-1- hydroxyl-2-vinyl esters (1.2c-f) with two new chiral centers, including a quaternary one, in good yields (> 81%), excellent cis stereoselectivities (diastereomeric ratio up to 50:1), and good to excellent enantiomer excesses (up to 99%). This easy entry to the highly functionalized chiral cyclic products under mild conditions will definitely make this catalytic enantioselective method a useful tool for the construction of the chiral skeletons of many medicinal agents and bioactive molecules. A new palladium-catalyzed enantioselective oxidative tandem cyclization method has been developed. In the presence of a catalytic amount of Pd(tfa) /(-)- sparteine with cheap and environmentally benign molecular oxygen as the terminal oxidant, a series of polycyclic indoline derivatives 2.2 with up to two stereocenters (2.2fb) are readily prepared in a single step in good yields and moderate to good enantiomer excesses (up to 91%; Scheme 2). These represent the first examples of enantioselective oxidative tandem cyclization reactions under aerobic conditions. A class of sterically bulky cyclic thiourea ligands (L1-11, Figure 1) have been synthesized. Ligand L1, with bulky t-butyl groups on the aryl moiety, was found to be effective in the palladium-catalyzed oxidation of alcohols under aerobic conditions, in which L1 exhibited good stability to oxidizing agents and efficiently prevented palladium from undergoing aggregation (Scheme 3). This new catalyst system has been applied to a wide variety of substrates such as benzylic alcohols, aliphatic secondary alcohols and allylic alcohols, producing the desired carbonyl compounds in moderate to excellent yields. However, the attempts to apply the chiral thiourea ligands (L7-11) to the palladium-catalyzed oxidative kinetic resolution of secondary alcohols did not give satisfactory results. Scheme 1 Chiral Lewis acid OEt OEt OH 81 87% yield n CH Cl, rt H 2 2 dr > 50:1 75 91% ee _ _ 1.1c 1.2c d d n = 1, 2 Chiral Lewis Acid: or Sc(OTf), Cu(OTf), 2 NN N N Ph Ph Ph Ph Cu(OTf) (20 mol%) 5R 5R 1R OR 1S OR OR L* (22 mol%), CH Cl, rt 2 2 OH 2R 2S OH L* = NN major 1.3e/f 1.1e R = CH 1.2e/f Ph Ph R = Bn 1.1f 91 94% yie