Download or read book Novel Ferrocene based Phosphine Ligands for Earth abundant Metal catalysed Asymmetric Hydrogenation written by Liyao Zeng and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chiral Phosphorous Based Ligands in Earth Abundant Transition Metal Catalysis written by Junliang Zhang and published by Elsevier. This book was released on 2023-05-27 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book Chiral Ferrocenes in Asymmetric Catalysis written by Li-Xin Dai and published by John Wiley & Sons. This book was released on 2010-02-01 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book meets the long-felt need for a reference on ferrocenes with the focus on catalysis. It provides a thorough overview of the synthesis and characterization of different types of chiral ferrocene ligands, their application to various catalytic asymmetric reactions, and versatile chiral materials as well as drug intermediates synthesized from them. Written by the "who's who" of ferrocene catalysis, this is a guide to the design of new ferrocene ligands and synthesis of chiral synthetic intermediates, and will thus be useful for organic, catalytic and synthetic chemists working in academia, industrial research or process development.
Download or read book Developing P Stereogenic Phosphine Ligand for Transition Metal Catalyzed Asymmetric Hydrogenation written by Heng Wang and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focusses on the discussion of how empirical ligand design works on the development of chiral pincer ligands in the field of asymmetric hydrogenation. Although the design art of bisphosphine ligands was well-established, this empirical guide for pincer ligand design is still ambiguous. Developing a ligand design guide based on the nature of metals enables synthetic chemists to improve the catalytic performance without investing large numbers of time, develop highly efficient catalysts for industrial uses, or explore new areas and mechanistic insights. Learning from the history of chiral pincer ligand development, over 14 categories of pincer ligands were reported according to the coordinating atoms by the time that this dissertation was prepared. Firstly, the ligand design and relevant catalytic performance of different ligand categories were summarized and discussed in prevalent noble metal catalysis such as Ru(II), Ir(III). Based on the nature of Fe(II) with respect to noble metals, a novel PNP-type ligand HengPNP (L) was designed and successfully synthesized. Empirical design perspectives were discussed, and the ligand was characterized by NMR, HRMS. Its corresponding Fe(II) complex was studied by X-ray crystallographic technique. However, the Fe(II) carbonyl complex was thermodynamically unstable under decent pressure. To better understand the catalytic performance and enantioselectivity of HengPNP(L), its corresponding Ir(III) complex was employed in the asymmetric hydrogenation of various ketone substrates. A C-H bond activation Ir(III) compound was successfully isolated. The Ir(III)/HengPNP was efficient on the asymmetric hydrogenation of orthosubstituted benzophenones with excellent ee and up to 500 TON. The catalyst was superior on the hydrogenation of bis-ortho-substituted benzophenones, excellent ee was achieved over the state-of-the-art Ir/f-amphox. DFT studies was conducted to shed light on the enantio-induction model of Ir/HengPNP. A novel enantio-induction mechanism was established-the change of rotation energy of ketone substrate under the steric pressure from rigid Ir/HengPNP, was responsible for the enantioselectivity. IrH/NH bifunctional mechanism was proposed for this protocol.
Download or read book Ferrocenes written by Petr Stepnicka and published by John Wiley & Sons. This book was released on 2008-04-15 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ferrocene—the prototypical metallocene—is a fascinating molecule. Even though it was first discovered over fifty years ago, research into ferrocene-containing compounds continues apace, largely stimulated by their successful applications in catalysis, materials science and bioorganometallic chemistry. Ferrocene derivatives are now recognised as useful starting materials for the preparation of new organometallic complexes and functional materials, efficient catalyst components, as well as redox-active modifiers to biomolecules. Ferrocenes: Ligands, Materials and Biomolecules provides the reader with a background overview and describes recent advances in the development and application of ferrocene compounds, including: synthesis and catalytic utilisation of chiral and non-chiral ferrocene ligands ferrocene-based sensors electrooptical materials ferrocene polymers liquid-crystalline materials crystal engineering with ferrocene compounds the bioorganometallic chemistry of ferrocene Ferrocenes: Ligands, Materials and Biomolecules is an essential guide for anyone working in the fields of organometallic synthesis and catalysis, materials science and bioorganometallic chemistry.
Download or read book Ferrocenes written by Antonio Togni and published by John Wiley & Sons. This book was released on 2008-07-11 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: With applications ranging from asymmetric catalysis to magnetic materials, ferrocene is one of the most versatile building blocks in synthesis. This book captures the multidisciplinary nature of ferrocene research, including topics such as ferrocene-containing polymers, ferrocene-containing thermotropic liquid crystals, chiral ferrocene derivatives, and ferrocene-containing charge-transfer materials. In addition, the reader will find * valuable information for planning syntheses * over 70 tables, making relevant data available at a glance * carefully selected references, providing an easy access to the primary literature Up-to-date, and written by leading international experts in the field, among them R. Deschenaux, C. D. Hall, Y. Butsugan, and R. Herrmann, this book is a welcome source of in-depth information for graduate students and professionals in organic, organometallic, and polymer chemistry, as well as in materials science.
Download or read book Cobalt Catalyzed Asymmetric Hydrogenation of Alkenes written by Hongyu Zhong and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal-catalyzed hydrogenation reactions represent one of the cornerstones in homogeneous catalysis. The asymmetric hydrogenation of unsaturated molecules is an atom-economical method for the synthesis of enantio-enriched compounds and is of particular interest to the pharmaceutical, agrochemical and fine chemical industries. Catalysts based on second- and third-row transition metals, including rhodium, iridium and ruthenium, have been intensively studied in the past five decades and applied widely in industries. Thorough mechanistic studies have been carried out, facilitating catalyst designs and process optimizations. There has been a growing interest in developing relatively Earth abundant, 3d transition metal hydrogenation catalysts based on manganese, iron, cobalt and nickel as alternatives to 4d and 5d transition metals owing to their reduced cost, uninterrupted supply chains and relatively lower toxicity. First-row metals have kinetically and thermodynamically accessible oxidation states separated by one-electrons, which offers opportunities for catalyst designs with new reaction mechanisms. Despite recent progress, the understandings of catalyst speciation upon in situ activation are still limited. Elucidating the coordination chemistry, oxidation states and spin states of active catalysts is of fundamental importance to inform catalyst designs and improve the catalytic performance of first-row metals.In this dissertation, the synthesis, characterization and mechanistic studies of a host of cobalt catalysts for the asymmetric hydrogenation of carbon?carbon double bonds will be introduced. In particular, cobalt catalysts supported by chiral bidentate phosphine ligands have been identified as a ?privileged? class of catalysts and will be the focus of this dissertation.The cobalt-catalyzed asymmetric hydrogenation affording the epilepsy medication, levetiracetam, has been developed and applied to a 200-gram, pilot scale hydrogenation. The unique stability and high activity of reduced cobalt catalysts in protic solvents represent major advances for first-row alkene hydrogenation catalysts. The reaction mechanisms of enamide asymmetric hydrogenation with the formally cobalt(0) catalysts were investigated by experimental and computational methods. The enantioselectivity originates from the different reactivity of a pair of diastereomeric bis(phosphine)cobalt(0)?enamide complexes with H2. The cobalt-catalyzed asymmetric hydrogenation of ?, ?-unsaturated carboxylic acids with unusual homolytic H2 cleavage has been achieved, affording chiral acid products including Naproxen, Flurbiprofen and an L-DOPA precursor. The reactions between bis(phosphine)cobalt(II) dialkyl precatalysts and alcohols have been investigated and the bis(phosphine)Co(II) alkoxide products remained catalytically active. A cobalt-promoted methanol dehydrogenation reaction was also studied. The long-sought-after cobalt analogs of Schrock-Osborn type rhodium catalysts have been synthesized and characterized. A cationic bis(phosphine)cobalt(I) arene catalyst was discovered to be highly active for the asymmetric hydrogenation affording the type 2 diabetes medication, Sitagliptin. The ligand substitution of bis(phosphine)cobalt(0)(diene) catalysts was investigated using kinetic methods establishing a dissociative substitution mechanism. Solid state parameters and electronic structure studies imply their alternative assignment as bis(phosphine)cobalt(II) metallacyclopropane, providing a rationale for the unique protic stability. A family of cobalt precatalysts supported by the bis(phosphine), (R,R)-BenzP*, has been synthesized and characterized. The magnetic properties of dimeric bis(phosphine)Co(I)monochloride precatalysts have also been elucidated.
Download or read book Synthesis and Applications of Chiral Phosphine Ligands to Catalytic Asymmetric Hydrogenation written by Antonio Belmiro Gil da Silva Fortes and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Olefin Polymerization written by Walter Kaminsky and published by Wiley-VCH. This book was released on 2006-08-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With an enormous velocity, olefin polymerization has expanded to one of the most significant fields in polymers since the first industrial use about 50 years ago. In 2005, 100 million tons of polyolefins were produced - the biggest part was catalyzed by metallorganic compounds. The Hamburg Macromolecular Symposium 2005 with the title "Olefin Polymerization" involved topics such as new catalysts and cocatalysts, kinetics, mechanism and polymer reaction engineering, synthesis of special polymers, and characterization of polyolefins. The conference combined scientists from different disciplines to discuss latest research results of polymers and to offer each other the possibility of cooperation. This is reflected in this volume, which contains invited lectures and selected posters presented at the symposium.
Download or read book Chiral Proline Based Ligands for Iridium Catalyzed Asymmetric Hydrogenation written by Denise Rageot and published by . This book was released on 2015-10 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Artificial Metalloenzymes and MetalloDNAzymes in Catalysis written by Montserrat Diéguez and published by John Wiley & Sons. This book was released on 2018-02-21 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important reference for researchers in the field of metal-enzyme hybrid catalysis Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a comprehensive review of the most current strategies, developed over recent decades, for the design, synthesis, and optimization of these hybrid catalysts as well as material about their application. The contributors—noted experts in the field—present information on the preparation, characterization, and optimization of artificial metalloenzymes in a timely and authoritative manner. The authors present a thorough examination of this interesting new platform for catalysis that combines the excellent selective recognition/binding properties of enzymes with transition metal catalysts. The text includes information on the various applications of metal-enzyme hybrid catalysts for novel reactions, offers insights into the latest advances in the field, and contains an informative perspective on the future: Explores the development of artificial metalloenzymes, the modern and strongly evolving research field on the verge of industrial application Contains a comprehensive reference to the research area of metal-enzyme hybrid catalysis that has experienced tremendous growth in recent years Includes contributions from leading researchers in the field Shows how this new catalysis combines the selective recognition/binding properties of enzymes with transition metal catalysts Written for catalytic chemists, bioinorganic chemists, biochemists, and organic chemists, Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a unique reference to the fundamentals, concepts, applications, and the most recent developments for more efficient and sustainable synthesis.
Download or read book Novel Dibenzofuran based Phosphine Ligands for Transition Metal Catalysis in Aqueous Media written by Arjan Erik Sollewijn Gelpke and published by . This book was released on 1998 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chiral Phosphine Ligands for Asymmetric Hydrogenation written by Elżbieta Łastawiecka and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organic Synthesis Using Transition Metals written by Roderick Bates and published by John Wiley & Sons. This book was released on 2012-04-30 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metals open up new opportunities for synthesis, because their means of bonding and their reaction mechanisms differ from those of the elements of the s and p blocks. In the last two decades the subject has mushroomed - established reactions are seeing both technical improvements and increasing numbers of applications, and new reactions are being developed. The practicality of the subject is demonstrated by the large number of publications coming from the process development laboratories of pharmaceutical companies, and its importance is underlined by the fact that three Nobel prizes have been awarded for discoveries in this field in the 21st Century already. Organic Synthesis Using Transition Metals, 2nd Edition considers the ways in which transition metals, as catalysts and reagents, can be used in organic synthesis, both for pharmaceutical compounds and for natural products. It concentrates on the bond-forming reactions that set transition metal chemistry apart from "classical" organic chemistry. Each chapter is extensively referenced and provides a convenient point of entry to the research literature. Topics covered include: introduction to transition metals in organic synthesis coupling reactions C-H activation carbonylative coupling reactions alkene and alkyne insertion reactions electrophilic alkene and alkyne complexes reactions of alkyne complexes carbene complexes h3- or p-allyl -allyl complexes diene, dienyl and arene complexes cycloaddition and cycloisomerisation reactions For this second edition the text has been extensively revised and expanded to reflect the significant improvements and advances in the field since the first edition, as well as the large number of new transition metal-catalysed processes that have come to prominence in the last 10 years – for example the extraordinary progress in coupling reactions using “designer” ligands, catalysis using gold complexes, new opportunities arising from metathesis chemistry, and C-H activation – without neglecting the well established chemistry of metals such as palladium. Organic Synthesis Using Transition Metals, 2nd Edition will find a place on the bookshelves of advanced undergraduates and postgraduates working in organic synthesis, catalysis, medicinal chemistry and drug discovery. It is also useful for practising researchers who want to refresh and enhance their knowledge of the field.
Download or read book Synthesis of Metal Complexes Supported by Ferrocene based Ligands for Tandem Catalysis and Applications Toward Liquid Cell Quantum Sensing written by Yi Shen and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developing methodologies to synthesize high-value products efficiently from simple substrates with control over the reactivity and selectivity is highly favored by the chemical industry. Employing assisted tandem catalysis, where serial reactions can be carried out in one pot, to achieve streamlined complex syntheses significantly reduces the number of steps and waste. Harnessing spatial and temporal control in catalysis enables approaches toward one-pot transformations and allows the integration of several catalytic processes. Ferrocene-based ligand-supported metal complexes represent a promising class of catalysts that can incorporate redox control over catalytic processes. We have developed a redox-controlled selective hydroamination reaction catalyzed by (thiolfan*)Zr(NEt2)2 (thiolfan*= 1, 1'-bis (2,4-di-tert-butyl-6-thiophenoxy)ferrocene). In situ switching of the catalyst's state during the reaction enables selectivity toward different substrates (Chapter 2).Incorporating the greenhouse gas CO2 into N-carboxyanhydrides (NCAs) followed by subsequent NCA utilization illustrates the possibility of integrating two synthetic steps in one vessel to afford a valuable material with possible CO2 recycling. To demonstrate the immense potential of integrating multi-step transformations in one pot, we developed a set of sustainable conditions for NCA synthesis (Chapter 3). Moreover, several metal catalysts supported by ferrocene-based ligands were found to catalyze NCA polymerization in the presence of a co-catalyst. To establish an integrated system composed of two incompatible processes, we aimed to compartmentalize the active reagents for each step. The structure of the ferrocene-based pro-ligand was modified for surface anchoring. Our efforts toward immobilizing ferrocene-supported metal catalysts onto conductive surfaces pave the way of achieving spatiotemporal control over the processes of NCA synthesis and polymerization (Chapter 4). In addition to the redox-switchable characteristic, ferrocene-based compounds provide a unique platform to support lanthanides and engender distinctive optical properties to them. We synthesized and characterized a series of ytterbium complexes displaying an ultra-narrow absorption in the ultraviolet-visible (UV-Vis) region. The extraordinarily narrow linewidth observed for (thiolfan)YbCl(THF) (thiolfan = 1,1'-bis(2,4-di-tert-butyl-6-thiomethylenephenoxy)ferrocene) allows us to investigate its applications toward magnetic field and liquid cell quantum sensing (Chapter 5).
Download or read book C2 and C3 Symmetric Chiral Bis and Tris phosphines in Asymmetric Catalysis written by Zhiming Xu and published by . This book was released on 2017 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 1. Effect of linker length on selectivity and cooperative reactivity in platinum-catalyzed asymmetric alkylation of bis(phenylphosphino)alkanes. The selectivity of catalytic asymmetric transformations of bifunctional symmetrical substrates often depends on the linker between the two reactive sites. If the catalyst controls the selectivity of reactions at both sites, the rac product will be formed in high enantiomeric ratio (er) via asymmetric amplification. Substrate control may augment this selectivity (positive cooperativity) or detract from it (negative cooperativity). We investigated the effect of linker length on the selectivity of catalytic asymmetric alkylation of the bis(secondary phosphines) PhHP-(CH2)[subscript n]PHPh (n = 2-6, 1a-e) with benzyl bromide using the base NaOSiMe3 and the catalyst precursor Pt((R,R)-Me-DuPhos)(Ph)(Cl). The two alkylations of bis(secondary phosphines) 1b-e with longer linker lengths (n = 3-6) showed identical selectivity, within experimental error. This catalyst control resulted in asymmetric amplification of rac-2. In contrast, the selectivity of the first alkylation of ethano-bridged 1a was lower than that in 1b-e (negative cooperativity), but the selectivity of the second alkylation increased due to positive cooperativity. I developed an efficient synthesis of the intermediate PhHP(CH2)2PPh(CH2Ph) (3a), which was required for determination of the selectivity of both steps in Pt-catalyzed alkylation of 1a. Possible mechanistic explanations for the observed dependence of selectivity on linker length are discussed in this chapter. Chapter 2. Selective formation of a C3-symmetric P-stereogenic tris(phosphine) via platinum-catalyzed asymmetric alkylation of a tris(secondary phosphine). C2-symmetric bis(phosphines) are the most common and successful ligands for metal-catalyzed reactions. Considering the great success of C2-symmetric ligands in asymmetric catalysis, C3-symmetric chiral tris(phosphines) were proposed to be useful in octahedral complexes, creating three homotopic sites. However, very little is known about C3-symmetric tris(phosphines) and their applications, mostly because of the lack of synthetic routes. We used Pt-catalyzed asymmetric alkylation to prepare enantiomerically enriched C3-symmetric, P-stereogenic tripodal tris(phosphines) from the tris(secondary phosphine) MeC(CH2PHPh)3 (5 a racemic mixture of C1- and C3-symmetric diastereomers) and a benzl bromide, utilizing the Pt((R,R)-Me-Duphos)(Ph)(Cl) catalyst precursor and a base. Pt-catalyzed alkylation of MeC(CH2PHPh)3 (5) with 2-cyanobenzyl bromide gave a mixture of tris(phosphines) MeC(CH2PPh(CH2Ar))3 (6) enriched in C3-6; oxidation of 6 by sulfur or H2O2 formed phosphine sulfide S-6 and oxide O-6. Hydrogen bonding between O-6 and the chiral amino acid (S)-Fmoc-Trip(BOC)-OH leads to the formation of new diastereomers. By integrating the 31P NMR spectra, I measured the dr and er values. Tris(phosphine) 6 was formed with a disatereomeric ratio (dr - C3/C1) of 2.1(2) and enantiomeric ratios of 54(10) and 3.8(7) for C3-3 and C1-3 respectively, which showed that the selectivity of the triple alkylation was not the same at each site (substrate control). Chapter 3. Screening racemic catalysts provides information on selectivity and mechanism in platinum-mediated asymmetric alkylation of bis- and tris(secondary phosphines). Screening racemic catalysts for transformations of symmetrical bifunctional substrates can provide information on the selectivity of an enantiopure catalyst. This idea was extended to Pt-catalyzed asymmetric alkylation of the bis(secondary phosphines) PhHP(CH2)3PHPh and PhHPCH2CMe2CH2PHPh and the tris(phosphine) MeC(CH2PHPh)3 with benzyl bromides using the catalyst precursors Pt(Me-DuPhos)(Ph)(CI) and Pt(BenzP*)(Ph)(CI). Depending on the catalyst and the substrate, these reactions occured under catalyst control without dissociation of the substrate, or under substrate control with or without substrate dissociation. The resulting structure-selectivity relationships provided mechanistic information. Chapter 4. Synthesis of new chiral bis(phospholane) metal-pincer complexes. Metal pincer complexes have received great attention in recent years as robust catalyst precursors. However, chiral metal pincer complexes for application in asymmetric catalysis are rare. Dialkylphospholane groups have an outstanding track record in asymmetric catalysis (commercial DuPhos and BPE ligands) and their steric properties can be easily controlled by tuning the alkyl substituents on the phospholane ring. These donors have similar steric and electronic properties to the common used bulky dialkylphosphine groups (P(t-Bu)2, P(i-Pr)2, etc.). Optimization of the synthesis of chiral PCP ligands bearing such phospholane groups and investigation of their coordination chemistry are discussed in this chapter.
Download or read book New Developments in Late Transition Metal Complexes of Ferrocene Based Ligands and Study of Their Efficiency as Catalysts in Asymmetric Reactions written by Marta Ayerbe Garcia and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
