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Development Of Optically Active Cyclopentadienyl Ruthenium Complexes And Their Application In Asymmetric Catalysis
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Book Synopsis Development of Optically Active Cyclopentadienyl Ruthenium Complexes and Their Application in Asymmetric Catalysis by : Meera Rao
Download or read book Development of Optically Active Cyclopentadienyl Ruthenium Complexes and Their Application in Asymmetric Catalysis written by Meera Rao and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Novel ruthenium complexes were developed containing a cyclopentadienyl (Cp) ligand tethered to a chiral sulfoxide, which also serves as a ligand. These complexes were synthesized via a [3+2] dehydrogenative cycloaddition between a Ru-[pi]-allyl complex and a terminal acetylene. Using the cycloaddition as a key step, the desired sulfoxide-ligated complexes could be prepared in six linear steps without the use of toxic metallating reagents such as thallium salts. A diverse library of complexes could be accessed through this method, which speaks to the robust nature of the key cycloaddition step. Using these complexes, a CpRu-catalyzed branched-selective asymmetric allylic alkylation (AAA) was developed. Using this method, various oxygen nucleophiles could be alkylated with allyl chloride electrophiles to provide branched ethers, esters and alcohols with high levels of regio- and enantioselectivity. These complexes also were effective in catalyzing an asymmetric redox bicycloisomerization to generate complex [3.1.0]- and [4.1.0]-azabicycles from simple propargyl alcohol substrates.
Book Synopsis Catalytic Asymmetric Cyclization Reactions of Chiral Cyclopentadienylruthenium and Indenylruthenium Complexes by : Michael Christian Ryan
Download or read book Catalytic Asymmetric Cyclization Reactions of Chiral Cyclopentadienylruthenium and Indenylruthenium Complexes written by Michael Christian Ryan and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Using transition metal catalysis to rapidly increase complexity for the construction of small molecules has been one of the most important areas of research in the field of synthetic organic chemistry. In particular, cyclopentadienylruthenium (CpRu) catalysis has previously been shown by our research group and others to be a selective, cost-effective, and atom-economical means of achieving this goal. In an effort to extend CpRu catalysis to enantioselective variants of these reactions, our group had previously developed CpRu complexes containing tethered chiral sulfoxides for their successful application towards asymmetric allylic substitution reactions. This work describes our efforts to expand the chemistry of these CpRu-sulfoxide complexes and to synthesize novel chiral CpRu and indenylruthenium (IndRu) catalysts for the discovery of new catalytic asymmetric cyclization reactions. CpRu-sulfoxide complexes were used to perform an asymmetric redox bicycloisomerization reaction that constructed [3.1.0] and [4.1.0] bicycles from propargyl alcohols. Initial reaction optimization was performed on 1,7-enynes due to the products' similarity to known triple-reuptake inhibitor GSK1360707. CpRu complex containing a tethered para-methoxy sulfoxide ligand proved to be the optimal catalyst for this reaction. Variation of the 1,7-enyne substrate structure revealed that a bulky 2,4,6-triisopropylbenzenesulfonyl (Tris) protecting group on the nitrogen-containing backbone was essential for observing high enantioselectivities for [4.1.0] bicycles. While THF proved to be the optimal solvent for redox isomerization of [4.1.0] bicycles, acetone provided the best results for [3.1.0] bicycles. Enantiomeric ratios as high as 98.5:1.5 were observed with Tris-containing [3.1.0] bicycles. The chemistry could be extended to 1,6-enynes containing other substrate tethers, including tosyl, diphenyl phosphoramidate, and dibenzyl malonate tethers. Nitrogen protecting groups were shown to be removable under reducing conditions. Catalysis performed with enantiomerically enriched propargyl alcohols revealed a matched/mismatched effect that was strongly dependent on the nature of the solvent. To the best of our knowledge, this methodology was the first example of a ruthenium-catalyzed asymmetric cycloisomerization reaction. Unfortunately, CpRu-sulfoxide complexes were shown to be inefficient and poorly selective catalysts for the enyne cycloisomerization and redox isomerization/C-H insertion reactions. We hypothesized that either the bound sulfoxide ligand was too electron-rich or that the catalyst had an insufficient number of coordination sites available for catalysis. In order to test our hypothesis, we synthesized CpRu complexes that contained more electron-withdrawing S-chiral ligands. While chiral sulfimide- and sulfinamide-containing complexes could promote enyne cycloisomerization, these catalysts were poorly enantioselective. These results led us to believe that the ligands were too weakly ligated to the metal center and decomplexed under the reaction conditions. Novel coordinatively unsaturated chiral indenylruthenium complexes with a tethered chiral sulfoxide were designed and synthesized. Enantiomeric ratios of up to 75:25 for enyne cycloisomerization and 84:16 for enyne hydroxycyclization could be obtained using these catalysts. When applied to the asymmetric redox isomerization/C-H insertion reaction, chiral indenylruthenium complexes could promote this reaction in up to 90:10 e.r. The main disadvantage of using these tethered complexes is that they are not commercially available and must be made through multistep syntheses. We discovered that commercially available catalyst CpRu(MeCN)3PF6, when used in conjunction with a chiral phosphoramidite ligand, can perform an asymmetric interrupted metallo-ene reaction of (E)-allylic chlorides in excellent enantioselectivity. To our knowledge, this represents the first example of using CpRu-phosphoramidite complexes for a catalytic asymmetric transformation. The C1-symmetry and 3,3'-substitution on the BINOL-based phosphoramidite were key to the high levels of enantioinduction observed. Carbocyclic and heterocyclic 5- and 6-membered rings could be constructed in> 20:1 d.r. and up to 99:1 e.r. As a demonstration of the utility of this methodology, diastereoselective Friedel-Crafts reactions were performed on the chiral benzylic alcohol products that were observed to proceed with retention of configuration.
Book Synopsis The Asymmetric Cyclopropanation of Olefins with Optically Active (salen)ruthenium(II) Complexes by : Jason Allen Miller
Download or read book The Asymmetric Cyclopropanation of Olefins with Optically Active (salen)ruthenium(II) Complexes written by Jason Allen Miller and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As an alternative to using an isolated chiral salen ruthenium catalyst, an optically pure Lewis base could be used to bind axially to the ruthenium center of an achiral catalyst, thus forcing the achiral salen ligand into an asymmetric conformation and inducing stereoselectivity. Enantiomeric excesses as high as 93% have been observed using this method. This novel and exciting modular approach is amenable to parallel-screening optimization and has great potential advantages over traditional catalyst development and synthesis methods.
Book Synopsis Chiral Cyclopentadienyl Ruthenium (II) Complexes by : David Kossler
Download or read book Chiral Cyclopentadienyl Ruthenium (II) Complexes written by David Kossler and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mots-clés de l'auteur: ruthenium ; cyclopentadienyl ligand ; asymmetric catalysis ; cycloisomerization.
Book Synopsis Chiral Ruthenium-cyclopentadienyl Complexes for Use in Asymmetric Synthesis by : Richard W. Kemp
Download or read book Chiral Ruthenium-cyclopentadienyl Complexes for Use in Asymmetric Synthesis written by Richard W. Kemp and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Catalytic Enantioselective Transformations with Chiral Cyclopentadienyl Ruthenium(II) Complexes by : Sung Hwan Park
Download or read book Catalytic Enantioselective Transformations with Chiral Cyclopentadienyl Ruthenium(II) Complexes written by Sung Hwan Park and published by . This book was released on 2020 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mots-clés de l'auteur: ruthenium ; cyclopentadienyl ligand ; asymmetric catalysis.
Book Synopsis Fundamentals of Asymmetric Catalysis by : Patrick J. Walsh
Download or read book Fundamentals of Asymmetric Catalysis written by Patrick J. Walsh and published by University Science Books. This book was released on 2009-01-02 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes the essential aspects of enantioselective catalysis, with chapters organised by concept rather than by reaction type. Each concept is supported by examples to give the reader broad exposure to a wide range of catalysts, reactions and reaction mechanisms.
Book Synopsis Ruthenium Oxidation Complexes by : William P. Griffith
Download or read book Ruthenium Oxidation Complexes written by William P. Griffith and published by Springer. This book was released on 2010-11-12 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ruthenium Oxidation Complexes explores ruthenium complexes, particularly those in higher oxidation states, which function as useful and selective organic oxidation catalysts. Particular emphasis is placed on those systems which are of industrial significance. The preparation, properties and applications of the ruthenium complexes are described, followed by a presentation of their oxidative properties and summary of the different mechanisms involved in the organic oxidations (e.g. oxidations of alcohols, alkenes, arenes and alkynes, alkanes, amines, ethers, phopshines and miscellaneous substrates). Moreover, future trends and developments in the area are discussed. This monograph is aimed at inorganic, organic, industrial and catalysis chemists, especially those who wish to carry out specific organic oxidations using catalytic methods.
Book Synopsis Development of Catalytic Asymmetric C-H Functionalizations with Chiral Cyclopentadienyl Iridium(III) Complexes by : Yun-Suk Jang
Download or read book Development of Catalytic Asymmetric C-H Functionalizations with Chiral Cyclopentadienyl Iridium(III) Complexes written by Yun-Suk Jang and published by . This book was released on 2019 with total page 411 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mots-clés de l'auteur: iridium ; cyclopentadienyl ligand ; asymmetric catalysis ; C-H functionalization.
Book Synopsis Asymmetric Catalysis by : B. Bosnich
Download or read book Asymmetric Catalysis written by B. Bosnich and published by Springer. This book was released on 2011-09-26 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rate of advance in areas of science is seldom constant. Usually certain fields effloresce with activity because of the ~ealization that solutions are possible to long standing important problems. So it is now with asymmetric catalysis, a field which promises to change profoundly the strategic thinking of synthetic chemists. As this Report will show, reagents which can induce catalytic enantiocontrol of chemical transformations could represent the ultimate synthetic method. Nearly all synthetic strategies of complex molecules involve steps which require enantiocontrol and, in many cases, a specific catalytic transformation embodying enan tiocontrol has enormous advantages in terms of the rate and economy of the reaction. Because asymmetric catalysis is in a formative stage, workers with different backgrounds have joined the field. This Workshop had representatives with organometallic, organic, structural, kinetic, enzymatic, microbiological and industrial backgrounds. Each had his own perspective and this Report represents a consensus of this group of eleven people. The result is probably as compre hensive and balanced a view of the subject as is possible at present. It is hoped that those who have until now had but a glancing interest in asymmetric catalysis will find this Report a useful indication of its present state. We believe that asymmetric catalysis will have an increasing impact on the development of chemistry and will eventually dominate much of synthetic and industrial chemistry.
Book Synopsis Synthesis of Organometallic Compounds by : Sanshiro Komiya
Download or read book Synthesis of Organometallic Compounds written by Sanshiro Komiya and published by John Wiley & Sons. This book was released on 1997-05-28 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inorganic Chemistry: Inorganic Chemistry: A Textbook Series This series reflects the breadth of modern research in inorganic chemistry and fulfils the need for advanced texts. The series covers the whole range of inorganic and physical chemistry, solid state chemistry, coordination chemistry, main group chemistry and bioinorganic chemistry. Synthesis of Organometallic Compounds A Practical Guide Edited by Sanshiro Komiya Tokyo University of Agriculture and Technology, Japan. This book describes the concepts of organometallic chemistry and provides an overview of the chemistry of each metal including the synthesis and handling of its important organometallic compounds. Synthesis of Organometallic Compounds: A Practical Guide provides: an excellent introduction to organometallic synthesis detailed synthetic protocols for the most important organometallic syntheses an overview of the reactivity, applications and versatility of organometallic compounds a survey of metals and their organometallic derivatives The purpose of this book is to serve as a practical guide to understanding the general concepts of organometallics for graduate students and scientists who are not necessarily specialists in organometallic chemistry.
Book Synopsis Discovery of Ruthenium Tris-phosphine Complexes for Poly-alcohol Functionalization and Alkene Hydroamination by : Christopher Hill
Download or read book Discovery of Ruthenium Tris-phosphine Complexes for Poly-alcohol Functionalization and Alkene Hydroamination written by Christopher Hill and published by . This book was released on 2018 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes the discovery and development of new ruthenium cis-triphosphine coordination complexes and their application towards catalytic functionalization of alcohols, ketones, and alkenes. Ruthenium-mediated transfer dehydrogenation of alcohols and subsequent complex ketone functionalization reactions enable the modification of the structures of complex molecules bearing multiple alcohol functionalities. Alteration of the ruthenium catalyst X-type scaffold generates a coordination complex that activates select amines for the direct Markovnikov hydroamination of terminal alkenes. Unactivated terminal alkenes bearing a diversity of functional groups and limiting amounts of alkene can be employed with acceptable yield. Internal alkenes undergo hydroamination with a selectivity that targets tandem isomerization-hydroamination. Chapter 1 surveys ruthenium-catalyzed hydrogenation and borrowing hydrogen chemistry with an emphasis on hydrogen transfer-mediated alcohol functionalization. Possible mechanisms of hydrogen transfer are considered and kinetic and thermodynamic considerations regarding hydrogen transfer and hydrogenation reactions are analyzed. This chapter then presents a survey of direct hydroamination reactions of alkenes with late metals and known hydroamination systems with ruthenium catalysts. Precedent in the fields of hydrogen transfer chemistry and hydroamination is described with an emphasis on the synthetic systems of highest utility or closest analogy to the transformations presented in this thesis. The utility, scope, and mechanism of known hydrogen transfer mediated functionalization reactions and seminal contributions to this field are described Chapter 2 presents the discovery and development of a new class of ruthenium cis-trisphosphine complexes bearing triflate ligands which catalyze a diverse array of organic transformations. The synthesis of this class of complexes is described in addition to select stoichiometric reactions of these complexes. This chapter presents the application of newly developed ruthenium catalysts towards the selective dehydrogenation of secondary alcohols in diverse complex polyhydroxylated natural products. The epimerization of select secondary alcohols in complex natural products is described. Several mechanistic experiments are given which support insight into the hydrogen transfer catalysts we have developed. Furthermore, this chapter covers the development of complex ketone functionalization chemistries to convert complex ketones to diverse functionalized complex molecules. In particular the description of chemistries for the incorporation of nitrogen based functional groups into complex ketones are presented. Chapter 3 presents the development of a new catalytic hydroamination system of terminal alkenes which tolerates limiting amounts of alkene and which enables the modification of a diverse scope of alkene substrates. The synthesis of a new class of catalysts based on a ruthenium trisphosphine scaffold with triflimide X-type ligands is presented along with their catalytic application. A synthetic route a novel osmium analog of the primary ruthenium scaffold is described. Several mechanistic experiments are presented to interpret the high reactivity of the system relative to previous systems in order to explain how a ruthenium catalyst has an activity that supersedes previous rhodium, iridium, and gold-based systems for hydroamination. Empirical observations including the generation of catalytic quantities of unsaturated intermediates in the hydroamination reaction, the tolerance of diverse solvents of widely varied dielectric properties, and the incorporation of deuterium at numerous locations in the starting materials and products the reaction are analyzed. Nuclear magnetic resonance spectroscopic and X-ray crystallographic studies are shown as preliminary support of a borrowing hydrogen type hydroamination mechanism and to support a preliminary proposal regarding the identity of ruthenium complexes along the catalytic cycle of hydroamination.
Book Synopsis Synthesis of a Chiral Ruthenium Organometallic Catalyst to Facilitate the Asymmetric Reduction of Ketones to Optically Active Alcohols by : Norman Kabir
Download or read book Synthesis of a Chiral Ruthenium Organometallic Catalyst to Facilitate the Asymmetric Reduction of Ketones to Optically Active Alcohols written by Norman Kabir and published by . This book was released on 1992 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Memoirs of the Institute of Scientific and Industrial Research, Osaka University by : Ōsaka Daigaku. Sangyō Kagaku Kenkyūjo
Download or read book Memoirs of the Institute of Scientific and Industrial Research, Osaka University written by Ōsaka Daigaku. Sangyō Kagaku Kenkyūjo and published by . This book was released on 2008 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Design and Synthesis of Electronically and Sterically Variable Chiral Cyclopentadienyl Transition Metal Complexes and Their Application in Asymmetric Transformations by : Timothy Michael Ramsey
Download or read book Design and Synthesis of Electronically and Sterically Variable Chiral Cyclopentadienyl Transition Metal Complexes and Their Application in Asymmetric Transformations written by Timothy Michael Ramsey and published by . This book was released on 1994 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Asymmetric Organocatalysis Combined with Metal Catalysis by : Bruce A. Arndtsen
Download or read book Asymmetric Organocatalysis Combined with Metal Catalysis written by Bruce A. Arndtsen and published by Springer Nature. This book was released on 2020-04-24 with total page 211 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Cyclometalation Reactions by : Iwao Omae
Download or read book Cyclometalation Reactions written by Iwao Omae and published by Springer Science & Business Media. This book was released on 2014-01-23 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a review of cyclometalation reactions and organometallic intramolecular-coordination five-membered ring products, the most active type of reactions in synthetic organic reactions and their products. Included is the discovery of intramolecular-coordination bonds in cyclometalation reactions and the characteristics of those reactions, as well as the reasons that their five-membered ring compounds are very easily synthesized through such reactions. In addition, the applications of cyclometalation reactions and five-membered ring products, synthetic applications, catalysts, and other products are described. These topics are of special interest for industrial researchers.
