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Author : René Michael Königs
Publisher :
ISBN 13 : 9783861303848
Total Pages : 113 pages
Book Rating : 4.3/5 (38 download)
Download or read book Development of New Catalytic C-C Bond Forming and Hydrogenation Reactions written by René Michael Königs and published by . This book was released on 2011 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher : Elsevier
ISBN 13 : 044323700X
Total Pages : 338 pages
Book Rating : 4.4/5 (432 download)
Download or read book Enantioselective C-C Bond Forming Reactions written by and published by Elsevier. This book was released on 2023-12-01 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Author : Liang Zhang
Publisher : Elsevier Inc. Chapters
ISBN 13 : 0128082283
Total Pages : 38 pages
Book Rating : 4.1/5 (28 download)
Download or read book New and Future Developments in Catalysis written by Liang Zhang and published by Elsevier Inc. Chapters. This book was released on 2013-07-11 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Abbas Hassan
Publisher :
ISBN 13 :
Total Pages : 670 pages
Book Rating : 4.:/5 (774 download)
Download or read book Development of New Transition Metal Catalyzed C-C Bond Forming Reactions and Their Application Toward Natural Product Synthesis written by Abbas Hassan and published by . This book was released on 2011 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Michael J. Krische research group we are developing new transition metal catalyzed Carbon-Carbon (C-C) forming reactions focusing on atom economy and byproduct free, environmental friendly approaches. We have developed a broad family of C-C bond forming hydrogenations with relative and absolute stereocontrol which provide an alternative to stoichiometric organometallic reagents in certain carbonyl and imine additions. Inspiring from the group work my goal was to develop new reactions, extend the scope of our group chemistry and their application towards synthesis of biologically active natural products. I have been part of enantioselective Rh catalyzed Aldol reaction of vinyl ketones to different aldehydes. Also, we have found that iridium catalyzed transfer hydrogenation of allylic acetates in the presence of aldehydes or alcohols results in highly enantioselective carbonyl allylation under the conditions of transfer hydrogenative. Based on this reactivity a concise enantio- and diastereoselective synthesis of 1,3-polyols was achieved via iterative chain elongation and bidirectional iterative asymmetric allylation was performed, which enables the rapid assembly of 1,3-polyol substructures with exceptional levels of stereocontrol. The utility of this approach stems from the ability to avoid the use of chirally modified allylmetal reagents, which require multistep preparation, and the ability to perform chain elongation directly from the alcohol oxidation level. This approach was utilized for the total synthesis of (+)-Roxaticin from 1,3-propanediol in 20 longest linear steps and a total number of 29 manipulations. Further, advancements were made in iridium catalyzed C-C bond formation under transfer hydrogenation. While methallyl acetate does not serve as an efficient allyl donor, the use of more reactive leaving group in methallyl chloride compensate for the shorter lifetime of the more highly substituted olefin [pi]-complex. Based on this insight into the requirements of the catalytic process, highly enantioselective Grignard-Nozaki-Hiyama methallylation is achieved from the alcohol or aldehyde oxidation levels. Also, a catalytic method for enantioselective vinylogous Reformatsky- type aldol addition was developed in which asymmetric carbonyl addition occurs with equal facility from the alcohol or aldehyde oxidation level. Good to excellent levels of regioselectivity and uniformly high levels of enantioselectivity were observed across a range of alcohols and aldehydes.
Author : Steven L Suib
Publisher : Newnes
ISBN 13 : 0444538836
Total Pages : 659 pages
Book Rating : 4.4/5 (445 download)
Download or read book New and Future Developments in Catalysis written by Steven L Suib and published by Newnes. This book was released on 2013-07-11 with total page 659 pages. Available in PDF, EPUB and Kindle. Book excerpt: New and Future Developments in Catalysis is a package of books that compile the latest ideas concerning alternate and renewable energy sources and the role that catalysis plays in converting new renewable feedstock into biofuels and biochemicals. Both homogeneous and heterogeneous catalysts and catalytic processes will be discussed in a unified and comprehensive approach. There will be extensive cross-referencing within all volumes.This volume presents a complete picture of all carbon dioxide (CO2) sources, outlines the environmental concerns regarding CO2, and critically reviews all current CO2 activation processes. Furthermore, the volume discusses all future developments and gives a critical economic analysis of the various processes. - Offers in-depth coverage of all catalytic topics of current interest and outlines future challenges and research areas - A clear and visual description of all parameters and conditions, enabling the reader to draw conclusions for a particular case - Outlines the catalytic processes applicable to energy generation and design of green processes
Author : Ming-yu Ngai
Publisher :
ISBN 13 :
Total Pages : 652 pages
Book Rating : 4.:/5 (355 download)
Download or read book Transition Metal-catalyzed Reductive C-C Bond Formation Under Hydrogenation and Transfer Hydrogenation Conditions written by Ming-yu Ngai and published by . This book was released on 2008 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon-carbon bond forming reactions are vital to the synthesis of natural products and pharmaceuticals. In 2003, the 200 best selling prescription drugs reported in Med Ad News are all organic compounds. Synthesizing these compounds involves many carbon-carbon bond forming processes, which are not trivial and typically generate large amounts of waste byproducts. Thus, development of an atom economical and environmentally benign carbon-carbon bond forming methodology is highly desirable. Hydrogenation is one of the most powerful catalytic reactions and has been utilized extensively in industry. Although carbon-carbon bond forming reactions under hydrogenation conditions, such as, alkene hydroformylation and the Fischer-Tropsch reaction are known, they are limited to the coupling of unsaturated hydrocarbons to carbon monoxide. Recently, a breakthrough was made by the Krische group, who demonstrated that catalytic hydrogenative C-C bond forming reactions can be extended to the coupling partners other than carbon monoxide. This discovery has led to the development of a new class of carbon-carbon bond forming reactions. Herein, an overview of transition metal-catalyzed reductive couplings of [pi]-unsaturated systems employing various external reductants is summarized in Chapter 1. Chapters 2-4 describe a series of rhodium- and iridium-catalyzed asymmetric hydrogenative couplings of various alkynes to a wide range of imines and carbonyl compounds. These byproduct-free transformations provide a variety of optically enriched allylic amines and allylic alcohols, which are found in numerous natural products, and are used as versatile precursors for the synthesis of many biologically active compounds. Transfer hydrogenation represents another important class of reactions in organic chemistry. This process employs hydrogen sources other than gaseous dihydrogen, such as isopropanol. The Krische group succeeded in developing a new family of transfer hydrogenative carbon-carbon bond formation reactions. Chapter 5 presents two novel ruthenium- and iridium-catalyzed transfer hydrogenative carbonyl allylation reactions. The catalytic system employing iridium complexes enables highly enantioselective carbonyl allylation from both the alcohol and aldehyde oxidation level. These systems define a departure from the use of preformed organometallic reagents in carbonyl additions that transcends the boundaries of oxidation level.
Author : Rui Shang
Publisher : Springer
ISBN 13 : 9811031932
Total Pages : 225 pages
Book Rating : 4.8/5 (11 download)
Download or read book New Carbon–Carbon Coupling Reactions Based on Decarboxylation and Iron-Catalyzed C–H Activation written by Rui Shang and published by Springer. This book was released on 2016-12-09 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the latest developments in new catalytic C–C bond formation methods using easily accessible carboxylate salts through catalytic decarboxylation with good atom economy, and employing the sustainable element iron as the catalyst to directly activate C–H bonds with high step efficiency. In this regard, it explores a mechanistic understanding of the newly discovered decarboxylative couplings and the catalytic reactivity of the iron catalyst with the help of density functional theory calculation. The thesis is divided into two parts, the first of which focuses on the development of a series of previously unexplored, inexpensive carboxylate salts as useful building blocks for the formation of various C–C bonds to access valuable chemicals. In turn, the second part is devoted to several new C–C bond formation methodologies using the most ubiquitous transition metal, iron, as a catalyst, and using the ubiquitous C–H bond as the coupling partner.
Author : Takahiko Akiyama
Publisher : John Wiley & Sons
ISBN 13 : 1119736412
Total Pages : 798 pages
Book Rating : 4.1/5 (197 download)
Download or read book Catalytic Asymmetric Synthesis written by Takahiko Akiyama and published by John Wiley & Sons. This book was released on 2022-05-27 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytic Asymmetric Synthesis Seminal text presenting detailed accounts of the most important catalytic asymmetric reactions known today This book covers the preparation of enantiomerically pure or enriched chemical compounds by use of chiral catalyst molecules. While reviewing the most important catalytic methods for asymmetric organic synthesis, this book highlights the most important and recent developments in catalytic asymmetric synthesis. Edited by two well-qualified experts, sample topics covered in the work include: Metal catalysis, organocatalysis, photoredox catalysis, enzyme catalysis C–H bond functionalization reactions Carbon–carbon bond formation reactions, carbon–halogen bond formation reactions, hydrogenations, polymerizations, flow reactions Axially chiral compounds Retaining the best of its predecessors but now thoroughly up to date with the important and recent developments in catalytic asymmetric synthesis, the 4th edition of Catalytic Asymmetric Synthesis serves as an excellent desktop reference and text for researchers and students, from upper-level undergraduates all the way to experienced professionals in industry or academia.
Author : Pher G. Andersson
Publisher : John Wiley & Sons
ISBN 13 : 3527330976
Total Pages : 375 pages
Book Rating : 4.5/5 (273 download)
Download or read book Innovative Catalysis in Organic Synthesis written by Pher G. Andersson and published by John Wiley & Sons. This book was released on 2012-05-14 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: C-H, C-O, C-C, and C-Heteroatom bond forming processes by using metal-ligand approaches for the synthesis of organic compounds of biological, pharmacological and organic nanotechnological utility are the key areas addressed in this book. Authored by a European team of leaders in the field, it brings together innovative approaches for a variety of catalysis reactions and processes frequently applied in organic synthesis into a handy reference work. It covers all major types of catalysis, including homogeneous, heterogeneous, and organocatalysis, as well as mechanistic and computational studies. Special attention is paid to the improvements in efficiency and sustainability of important catalytic processes, such as selective oxidations, hydrogenation, and cross-coupling reactions, and to their utilization in industry. The result is a valuable resource for advanced researchers in both academia and industry, as well as graduate students in organic chemistry aiming for chemo-, regio- or stereoselective synthesis of organic compounds by using novel catalytic systems.
Author : An-Hua Liu
Publisher : Elsevier Inc. Chapters
ISBN 13 : 0128082232
Total Pages : 113 pages
Book Rating : 4.1/5 (28 download)
Download or read book New and Future Developments in Catalysis written by An-Hua Liu and published by Elsevier Inc. Chapters. This book was released on 2013-07-11 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jongrock Kong
Publisher :
ISBN 13 :
Total Pages : 764 pages
Book Rating : 4.:/5 (174 download)
Download or read book Rh-catalyzed Reductive Coupling Under Hydrogenation Conditions and Nucleophilic Catalysis Via Phosphine Conjugate Addition written by Jongrock Kong and published by . This book was released on 2007 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt: At the threshold of the 21st centry, a new set of challenges is defined by the need to develop sustainable means of preparing chemical commodities demanded by society. Hence, such concepts as atom economy, step economy, and 'green chemistry' have become the requirements for the development of synthetic reactions. Hydrogenation is one of the most powerful catalytic methods which successfully satisfy the stated requirements of modern chemistry. Accordingly, catalytic hydrogenation has been tremendously utilized in industrial settings. The profound impact of hydrogenation portended a powerful approach to reductive carbon-carbon bond formation under hydrogenation conditions, resulting in the discovery of the Fischer-Tropsch process and hydroformylation. However, since this discovery, processes have restricted to the incorporation of a single carbon monoxide unit. Even though there are a few seminal contributions, systematic efforts toward the development of hydrogen-mediated carboncarbon bond forming processes beyond hydroformylation have been absent from the literature. In an exciting advance, the Krische group has shown that it is possible to reductively couple two or more organic molecules simply through their exposure to gaseous hydrogen in the presence of a metal catalyst. This finding has led to the development of a broad, new family of hydrogen-mediated C-C bond formation. Herein, related to hydrogen-mediated C-C bond formation, the overview of metal catalyzed intermolecular reductive coupling in the presence of reducing agents such as borane, silane, alane, metal, and hydrogen is presented. Chapter 2 describes systematic approaches to the development of hydrogen-mediated C-C bond formation and successful preliminary results achieved by our research group. Chapters 3 and 4 will describe the further extension of these hydrogen-mediated C-C bond formations including (1) hydrogen-mediated reductive couplings of conjugated alkynes with iminoacetates, (2) hydrogen-mediated reductive couplings of 1,3-enynes with [alpha]-ketoesters, and (3) hydrogen-mediated multicomponent reductive couplings. The development of catalytic systems for the nucleophilic activation of enones using phosphine catalysts has received attractive attention. Recently, an intramolecular variant of the Rauhut-Currier reaction was developed in our lab. To further extend nucleophilic phosphine catalysis, we have sought to develop new catalytic methodology via phosphine conjugate addition. Chapter 5 describes two new methodologies related to their area: (1) catalytic cycloallylation via nucleophilic phosphine catalysis and (2) allylic amination of Morita-Baylis-Hillman acetates.
Author : Koichi Mikami
Publisher : John Wiley & Sons
ISBN 13 : 047009799X
Total Pages : 436 pages
Book Rating : 4.4/5 (7 download)
Download or read book New Frontiers in Asymmetric Catalysis written by Koichi Mikami and published by John Wiley & Sons. This book was released on 2007-02-16 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: A compilation of recent advances and applications in asymmetric catalysis The field of asymmetric catalysis has grown rapidly and plays a key role in drug discovery and pharmaceuticals. New Frontiers in Asymmetric Catalysis gives readers a fundamental understanding of the concepts and applications of asymmetric catalysis reactions and discusses the latest developments and findings. With contributions from preeminent scientists in their respective fields, it covers: * "Rational" ligand design, which is critically dependent on the reaction type (reduction, oxidation, and C-C bond formation) * Recent findings on activation of C-H bonds, C-C bonds, and small molecules (C=O, HCN, RN=C, and CO2) and the latest developments on C-C bond reorganization, such as metathesis * Advances in "chirally economical" non-linear phenomena, racemic catalysis, and autocatalysis * Some of the recent discoveries that have led to a renaissance in the field of organocatalysis, including the development of chiral Brönstead acids and Lewis acidic metals bearing the conjugate base of the Brönstead acids as the ligands and the chiral bi-functional acid/base catalysts The book ends with a thought-provoking perspective on the future of asymmetric catalysis that addresses both the challenges and the unlimited potential in this burgeoning field. This is an authoritative, up-to-date reference for organic chemists in academia, government, and industries, including pharmaceuticals, biotech, fine chemicals, polymers, and agriculture. It is also an excellent textbook for graduate students studying advanced organic chemistry or chemical synthesis.
Author : Khoa Dang Nguyen (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : 1316 pages
Book Rating : 4.:/5 (12 download)
Download or read book Development of Neutral Redox Carbon-carbon Bond Forming Reactions Via Transition Metal-catalyzed Transfer Hydrogenation written by Khoa Dang Nguyen (Ph. D.) and published by . This book was released on 2017 with total page 1316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since C-C bonds form the backbone of every organic molecule and reside at the heart of chemical science, the development of new efficient methods for promoting C-C bond formation is of great significance. Inspired and expanded from traditional Grignard reactions, the work presented in this dissertation focuses on metal catalyzed neutral redox-triggered carbonyl addition via transfer hydrogenation. Advancing the native reducing capability of alcohols, employment of catalytic transition metals enables the formation of nucleophile-electrophile pairs in situ, en route to the products of formal alcohol C-H functionalization. These redox-triggered reactions circumvent the stoichiometric metallated byproduct waste and streamline the construction of complex molecules from simple and/or readily available feedstocks. The research reported herein discloses new developed methodologies of ruthenium and iridium catalyzed coupling reactions of primary and secondary alcohols with various pi-unsaturates. These studies contribute to the growing body of redox-triggered alcohol C-C couplings - new carbonyl addition chemistry that extends beyond the use of premetalated reagents.
Author : Brett Loveless
Publisher :
ISBN 13 :
Total Pages : 224 pages
Book Rating : 4.:/5 (839 download)
Download or read book C-O Bond Activation and C-C Bond Formation Paths in Catalytic CO Hydrogenation written by Brett Loveless and published by . This book was released on 2012 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamental mechanistic details regarding C-O bond activation and C-C bond formation remain unknown in catalytic CO hydrogenation to heavy hydrocarbons (Fischer-Tropsch synthesis, FTS). This study combines infrared spectroscopic and density functional theory methods (DFT) to first identify relevant surface CO coverages during FTS; reaction energy profiles are then calculated using DFT to determine the most facile path for C-O bond activation on Ru cluster surfaces. Kinetic responses of CO conversion rates and product selectivities to changes in H2 and CO pressures are measured in a packed-bed reactor at differential conversions on supported Ru catalysts to develop kinetic rate equations for FTS and corresponding sets of elementary reaction steps consistent with such equations. The effects of Ru cluster size on CO turnover rates, CO adsorption equilibrium constants, and CO conversion activation energies are also investigated to identify the Ru coordination environment in which C-O bonds are activated during FTS. C-C bond formation paths are then probed by measuring the effects of H2 and CO pressures on chain termination parameters, which provide a direct comparison between chain termination and chain propagation rates for all hydrocarbon products. DFT simulations of chain termination and chain propagation reactions as a function of carbon number are also performed to elucidate relevant C-C bond formation paths and to explain the apparent difficulty in forming the initial C-C bond during FTS. Calculated CO adsorption energies decrease with increasing CO coverage on flat extended Ru(0001) surfaces and on 201-atom Ru cluster surfaces(Ru201) due to repulsive intermolecular CO-CO interactions; such repulsive interactions are alleviated on convex Ru201 cluster surfaces, which can also accommodate CO coverages above a stoichiometric monolayer by forming geminal di-carbonyl species (also identified by infrared spectroscopy of CO adsorbed on Ru/SiO2 catalysts) at under-coordinated corner and edge Ru atoms. DFT-derived activation barriers for H-assisted CO activation paths on Ru atoms in high-coordination environments are much smaller than such barriers for direct CO bond cleavage, suggesting that CO species can be activated via H-assistance on low-index surfaces. Direct CO activation barriers on under-coordinated corner and step-edge sites are larger than those on high-coordination sites because of unfavorable interactions between di-carbonyl species and vicinal C-O activation transition states. DFT results also show that C-O bond activation during FTS is irreversible, and any direct CO dissociation path, as a result, is inconsistent with the reported effects of H2 and COpressures on FTS rates. Kinetic responses of CO conversion turnover rates and oxygen rejection selectivities (in the form of H2O/CO2 formation rate ratios) are consistent with CO activation occurring predominantly via H-assisted paths on Ru catalysts, irrespective of Ru cluster size. CO adsorption equilibrium constants and CO conversion activation energies, measured during FTS reactions, are the same for both small and large Ru clusters, suggesting that CO activation occurs in similar environments on both particle sizes. Turnover rates are smaller on small (~ 1 nm) Ru clusters than rates on large (~ 7 nm) Ru clusters when rates are normalized by the total number of exposed Ru atoms. Such differences in turnover rates become much smaller, however, when rates are normalized by the number of exposed Ru atoms in low-index (111) planes; CO activation reactions, as a result, likely occur on Ru atoms in high-coordination environments on both small and large Ru clusters. Increases in H2 pressures increases CH4 selectivities and decreases C5+ selectivities because chain termination is proportional to the concentration of surface hydrogen atoms (H*); chain growth reactions are favored at high CO pressures where termination is suppressed. Chain termination parameters for C1 species (to CH4) are much larger than such parameters for C2+ species; these parameters depend exponentially on the difference in chain termination and chain propagation barriers for each carbon number. DFT-derived activation barriers for termination reactions (via hydrogenation of surface alkyl species) are small and independent of chain length because such reactions are exothermic and proceed via early transition states; chain propagation reactions (via alkyl migration to vicinal CO* species), however, proceed through late transition states where surface-alkyl bonds are broken completely. Surface methyl (CH3*) species are bound to surfaces much more strongly than ethyl (C2H5*) and propyl (C3H7*) species; C1 propagation barriers, as a result, are much larger than such barriers for C2+ hydrocarbons, a result that is consistent with measured chain termination parameters on supported Ru catalysts. A steady-state treatment of reactive intermediates shows that CO conversion rate equations must include terms for CO consumption via CO activation as well as for consumption via chain growth with CO* monomers. This study unites experiment and theory to investigate fundamental C-O bond activation and C-C bond formation reactions on relevant catalyst surfaces during FTS. Kinetic and selectivity measurements remain vital in the understanding of elementary steps involved in bond making and bond breaking events in FTS reactions; theoretical tools can be used to investigate elementary reactions under conditions inaccessible to experimental techniques. Theoretical investigations of FTS reactions must be performed on cluster surfaces at high CO* coverages that prevail during relevant conditions because CO* coverages affect thermodynamic and kinetic parameters included in apparent activation energies. High CO* coverages also weaken Ru-CO bonds, consistent with quasi-equilibrated CO adsorption-desorption processes during FTS. This study is an important example of how theoretical calculations performed on relevant surfaces at relevant coverages are an invaluable compliment to experimental studies of metal-catalyzed chemical reactions.
Author : Hema Ramsurn
Publisher : Elsevier Inc. Chapters
ISBN 13 : 0128081643
Total Pages : 42 pages
Book Rating : 4.1/5 (28 download)
Download or read book New and Future Developments in Catalysis written by Hema Ramsurn and published by Elsevier Inc. Chapters. This book was released on 2013-07-13 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Sumit Bhaduri
Publisher : John Wiley & Sons
ISBN 13 : 1118872517
Total Pages : 302 pages
Book Rating : 4.1/5 (188 download)
Download or read book Homogeneous Catalysis written by Sumit Bhaduri and published by John Wiley & Sons. This book was released on 2014-09-11 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade, the area of homogeneous catalysis with transition metal has grown in great scientific interest and technological promise, with research in this area earning three Nobel Prizes and filing thousands of patents relating to metallocene and non-metallocene single site catalysts, asymmetric catalysis, carbon-carbon bond forming metathesis and cross coupling reactions. This text explains these new developments in a unified, cogent, and comprehensible manner while also detailing earlier discoveries and the fundamentals of homogeneous catalysis. Serving as a self-study guide for students and all chemists seeking to gain entry into this field, it can also be used by experienced researchers from both academia and industry for referring to leading state of the art review articles and patents, and also as a quick self-study manual in an area that is outside their immediate expertise. The book features: • Topics including renewable feed stocks (biofuel, glycerol), carbon dioxide based processes (polycarbonates), fluorous solvents, ionic liquid, hydroformylation, polymerization, oxidation, asymmetric catalysis, and more • Basic principles of organometallic chemistry, homogeneous catalysis, and relevant technological issues • Problems and answers, industrial applications (case studies), and examples from proven industrial processes with clear discussions on environmental and techno-commercial issues • Extensive references to cutting edge research with application potential and leading patents • Tables and illustrations to help explain difficult concepts
Author : Xiangyu Wu
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (14 download)
Download or read book New Radical Approaches to C-C Bond Formation in Small Molecules written by Xiangyu Wu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radical chemistry has emerged as a cornerstone in modern organic synthesis, providing chemists with numerous new tools to rapidly expand reactivity and chemical space in academic and industrial research. However, the high reactivity of organic radicals is a double-edged sword, as the selectivity of these fleeting intermediates can be difficult to control in the presence of multiple chemotypes. In addition, catalyst-controlled regio- and stereoselective reactions involving free radical intermediates remain limited, and the discovery of such processes is still highly desirable. From the perspective of creating new molecules, carbon-carbon bond forming reactions are among the most important transformations in organic chemistry. In this regard, the development of catalytic strategies that enable new C-C bond forming transformations with precise control over chemo-, regio-, and stereoselectivity could substantially impact organic synthesis.In this dissertation, we begin with an overview of historical development of radical organic chemistry (chapter 1). In the same chapter, we present a brief introduction to radical relay catalysis and showcase recent advance of this strategy in organic synthesis. More relevant to the major strategy used in this dissertation, historical achievements and recent innovation of TiIII/IV redox catalysis are discussed in detail in this chapter with an emphasis on the general mechanistic principle. In chapter 2, we present the development of a TiIII-catalyzed radical addition of 2° and 3° alkyl chlorides to electron-deficient alkenes. Mechanistic data are consistent with inner-sphere activation of the C-Cl bond featuring TiIII -mediated Cl atom abstraction. Evidence suggests that the active TiIII catalyst is generated from the TiIV precursor in a Lewis-acid-assisted electron transfer process. In chapter 3, we report a systematic mechanistic study on Ti-catalyzed enantioselective [3+2] cycloaddition of cyclopropyl ketone and alkenes in collaboration with Sigman group. In this reaction, through a suite of computational and experimental mechanistic studies, catalyst distortion was elucidated to dictate stereochemical outcomes. The mechanistic insights aided in our search for an improved catalyst, which substantially expanded the reaction scope and provided a collection of synthetically interesting products in high diastereo- and enantioselectivity. A catalyst-substrate matrix based on the new catalysts allowed for the development of an MLR statistical model that could predict the performance of each catalyst with a novel substrate. The predictive power of this model was demonstrated through accurate prediction of enantioselectivity outcomes for various substrates in reactions with the improved catalyst. Work presented in this chapter demonstrates the utility of mechanistic studies in guiding catalyst optimization toward a more broadly applicable transformation. In chapter 4, we show the development a reductive strategy for the generation of Co-H species from readily available acetic acid and demonstrate its application in the deuteration and hydroarylation of alkenes. The reaction development was guided by systematic spectroscopic and electroanalytical techniques, which provided both qualitative and quantitative information about the formation, identity, and reactivity of Co-H intermediates. At the end of each chapter, we summarize the development of these radical transformations and raise up questions. For each system, we try to not only point out the limitation of current reactions but also provide an outlook for the future direction.
