Radical And Ion Pairing Strategies In Asymmetric Organocatalysis

Book Description :

Considering the challenge of sustainability facing our society in the coming decades, catalysis is without any doubt a research area of major importance. In this regard, asymmetric organocatalysis, now considered a pillar of green chemistry, deserves particular attention. The first chapter of this volume examines the topic of asymmetric organocatalysis in light of radical chemistry. Recent important progress in this field has been attained by promoting the formation and harnessing the high reactivity of open-shell intermediates. Merging organocatalysis with radical chemistry has been the key to solving some longstanding bottlenecks, and has also significantly contributed to reinforcing the key role of organocatalysis in asymmetric catalysis. This chapter presents the most significant developments in this area, with a particular focus on asymmetric SOMO- and photoredox-organocatalyzed transformations. Chapter 2 focuses on quaternary ammonium salts (R4N+X-), especially chiral derivatives, and their behavior as unique catalysts in organocatalysis. Forming chiral ion-pairs capable of promoting asymmetric reactions, they also operate as unique “transporters involved in phase transfer catalytic processes between liquid–liquid or liquid–solid systems. Furthermore, they offer unique opportunities when forming cooperative ion-paired entities R4N+X-, allowing a synergistic implication of the counter-ion X- either as Brønsted bases or Lewis bases. Specific design of such chiral catalysts in modern chemistry and better insight into their mode of activation facilitates efficient and unprecedented chemical transformations. This chapter provides an overview of the use of chiral quaternary ammonium salts in organocatalysis, emphasizing both general mechanistic aspects and the scope of this approach. Presents the most significant developments with a particular focus on asymmetric SOMO- and photoredox-organocatalyzed transformations Givies a larger overview of chiral ammonium salts in organocatalysis rather than a specific review dedicated to specialists in this area Affords a historical evolution of this field of research

Book Description :

Asymmetric Organocatalysis Comprehensive resource on the latest and most important developments in the highly vivid field of asymmetric organocatalysis The book provides a comprehensive overview of the most important advancements in the field of asymmetric organocatalysis that have occurred within the last decade. It presents valuable examples of newly developed synthetic methodologies based on various organocatalytic activation modes. Special emphasis is given to strategies where organocatalysis is expanding its potential by pushing the boundaries and founding new synergistic interactions with other fields of synthetic chemistry, such as metal catalysis, photocatalysis, and biocatalysis. The application of different concepts (such as vinylogy, dearomatization, or cascade reactivity), resulting in the development of new functionalization strategies, is also discussed. Sample topics covered within the book include: New developments in enantioselective Brønsted acid catalysis with strong hydrogen-bond donors Asymmetric phase-transfer catalysis, from classical applications to new concepts Halogen-bonding organocatalysis Asymmetric electrochemical organocatalysis and synergistic organo-organocatalysis Immobilized organocatalysts for enantioselective continuous flow processes Mechanochemistry and high-pressure techniques in asymmetric organocatalysis Useful tools in elucidation of organocatalytic reaction mechanisms With an overall focus on new reactions and catalysts, this two-volume work is an indispensable source for everyone working in the field of asymmetric organocatalysis.

Book Description :

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.

Book Description :

In the past decade a new era in asymmetric catalysis has been realised by the discovery of L-proline induced chiral enamines from carbonyls. Inspired by this, researchers have developed many other primary catalytic species in situ, more recently secondary catalytic species such as aminals have been identified for use in asymmetric synthesis. High-yielding asymmetric synthesis of bioactive and natural products through mild catalysis is an efficient approach in reaction engineering. In the early days, synthetic chemists mainly focused on the synthesis of complex molecules, with less attention on the reaction efficiency and eco-friendly conditions. Recent investigations have been directed towards the development of atom economy, eco-friendly and enantioselective synthesis for more targeted and efficient synthesis. Building on the momentum of this rapidly expanding research area, Dienamine Catalysis for Organic Synthesis will provide a comprehensive introduction, from the preformed species, in situ generation and onto their applications in the synthesis of bioactive molecules and natural products.

Book Description :

Organocatalysis has recently attracted enormous attention as green and sustainable catalysis. It was realized as a fundamental field providing wide families of catalysts for important organic transformations. It will certainly develop in the future. Given the diversity of accessible transformations, metal-catalyzed reactions have become major tools in organic synthesis that will undoubtedly continue to have an important impact in the future. Alternatively, over the last years, a metal-free approach such as organocatalysis has reached a level of faithfulness, allowing researchers to discover new catalytic systems based on engagement of new or early-prepared organic molecules as organocatalysts. Organocatalysis meets green chemistry principles, especially the reduction of toxicity and chemical accidents, the biodegradability, and the use of benign and friendlier reaction media and conditions.

Book Description :

Organocatalysis is considered today one of the three pillars in asymmetric catalysis, along with biocatalysis and organometallic catalysis. The possibility to combine organocatalysis with radical chemistry, photocatalysis and enabling technologies opened new avenues in organic synthesis.

Book Description :

Heterocycles feature widely in natural products, agrochemicals, pharmaceuticals and dyes, and their synthesis is of great interest to synthetic chemists in both academia and industry. The contributions of recent applications of new methodologies in C–H activation, photoredox chemistry, cross-coupling strategies, borrowing hydrogen catalysis, multicomponent and solvent-free reactions, regio- and stereoselective syntheses, as well as other new, attractive approaches for the construction of heterocyclic scaffolds are of great interest. This Special Issue is dedicated to featuring the latest research that is ongoing in the field of heterocyclic synthesis. It is expected that most submissions will focus on five- and six-membered oxygen and nitrogen-containing heterocycles, but structures incorporating other rings/heteroatoms will also be considered. Original research (communications, full papers and reviews) that discusses innovative methodologies for assembling heterocycles with potential application in materials, catalysis and medicine are therefore welcome.

Book Description :

Download Dissertation Abstracts International book written by , available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Book Description :

Uniting the key organic topics of total synthesis and efficient synthetic methodologies, this book clearly overviews synthetic strategies and tactics applied in total synthesis, demonstrating how the total synthesis of natural products enables scientific and drug discovery. • Focuses on efficiency, a fundamental and important issue in natural products synthesis that makes natural product synthesis a powerful tool in biological and pharmaceutical science • Describes new methods like organocatalysis, multicomponent and cascade reactions, and biomimetic synthesis • Appeals to graduate students with two sections at the end of each chapter illustrating key reactions, strategies, tactics, and concepts; and good but unfinished total synthesis (synthesis of core structure) before the last section • Compiles examples of solid phase synthesis and continuing flow chemistry-based total synthesis which are very relevant and attractive to industry R&D professionals

Book Description :

A much-needed overview of the synthesis of chiral Brønsted acids and their applications in various organic transformations. The internationally recognized and highly respected expert authors summarize the most significant advances in this new and dynamically progressing field, with a special emphasis on BINOL-derived phosphoric acids. They also describe other catalysts, such as C-H, TADDOL-derived Brønsted, and sulfonic acids. For easy navigation, the chapters are organized in the first instance according to reactive intermediate and then sub-divided by reaction type. An appendix with selected experimental details for benign and straight-forward procedures rounds of the book, making this the number-one information source for organic chemists in academia and industry.

Book Description :

Structural, Physical, and Chemical Properties of Fluorous Compounds, by J.A. Gladysz Selective Fluoroalkylation of Organic Compounds by Tackling the “Negative Fluorine Effect”, by W. Zhang, C. Ni and J. Hu Synthetic and Biological Applications of Fluorous Reagents as Phase Tags, by S. Fustero, J. L. Aceña and S. Catalán Chemical Applications of Fluorous Reagents and Scavengers, by Marvin S. Yu Fluorous Methods for the Synthesis of Peptides and Oligonucleotides, by B. Miriyala Fluorous Organic Hybrid Solvents for Non-Fluorous Organic Synthesis, by I. Ryu Fluorous Catalysis: From the Origin to Recent Advances, by J.-M. Vincent Fluorous Organocatalysis, by W. Zhang Thiourea Based Fluorous Organocatalyst, by C. Cai Fluoroponytailed Crown Ethers and Quaternary Ammonium Salts as Solid–Liquid Phase Transfer Catalysts in Organic Synthesis, by G. Pozzi and R. H. Fish Fluorous Hydrogenation, by X. Zhao, D. He, L. T. Mika and I. T. Horváth Fluorous Hydrosilylation, by M. Carreira and M. Contel Fluorous Hydroformylation, by X. Zhao, D. He, L.T. Mika and I. Horvath Incorporation of Fluorous Glycosides to Cell Membrane and Saccharide Chain Elongation by Cellular Enzymes, by K. Hatanaka Teflon AF Materials, by H. Zhang and S. G. Weber Ecotoxicology of Organofluorous Compounds, by M. B. Murphy, E. I. H. Loi, K. Y. Kwok and P. K. S. Lam Biology of Fluoro-Organic Compounds, by X.-J. Zhang, T.-B. Lai and R. Y.-C. Kong

Book Description :

Explores the potential of new types of anion-binding catalysts to solve challenging synthetic problems Anion-Binding Catalysis introduces readers to the use of anion-binding processes in catalytic chemical activation, exploring how this approach can contribute to the future design of novel synthetic transformations. Featuring contributions by world-renowned scientists in the field, this authoritative volume describes the structure, properties, and catalytic applications of anions as well as synthetic applications and practical analytical methods. In-depth chapters are organized by type of catalyst rather than reaction type, providing readers with an accessible overview of the existing classes of effective catalysts. The authors discuss the use of halogens as counteranions, the combination of (thio)urea and squaramide-based anion-binding with other types of organocatalysis, anion-binding catalysis by pnictogen and tetrel bonding, nucleophilic co-catalysis, anion-binding catalysis by pnictogen and tetrel bonding, and more. Helping readers appreciate and evaluate the potential of anion-binding catalysis, this timely book: Illustrates the historical development, activation mode, and importance of anion-binding in chemical catalysis Explains the analytic methods used to determine the anion-binding affinity of the catalysts Describes catalytic and synthetic applications of common NH- and OH-based hydrogen-donor catalysts as well as C-H triazole/triazolium catalysts Covers amino-catalysis involving enamine, dienamine, or iminium activation approaches Discusses new trends in the field of anion-binding catalysis, such as the combination of anion-binding with other types of catalysis Presenting the current state of the field as well as the synthetic potential of anion-binding catalysis in future, Anion-Binding Catalysis is essential reading for researchers in both academia and industry involved in organic synthesis, homogeneous catalysis, and pharmaceutical chemistry.

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Download Journal book written by American Chemical Society, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Book Description :

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 Description :

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 Description :

The use of organocatalysts able to photocatalyze an organic reaction is a rapidly growing field. These photocatalyzed transformations are more environmentally sustainable with respect to the use of expensive/toxic metal-based (photo)catalysts.Based on the authors' extensive experience in photogenerated intermediates, this book presents an overview on photocatalyzed organic processes having a synthetic significance, where an organic molecule functions as the photocatalyst.After a brief introduction defining the nature and the characteristics of a photoorganocatalyst (POC), the chapters are organized according to the class of POC used, as detailed below.Each chapter begins with a summary of the photophysical characteristics of the POCs and is followed by selected examples of synthetic applications. The last two chapters are devoted to the adoption of photoorganocatalysis in polymerization and to flow photoorganocatalysis. These in-depth explanations and practical applications make this title an essential reading for any chemistry student interested in organic (sustainable) synthesis.

Book Description :

SOMO and Photoredox Activations in Asymmetric Organocatalysis presents the most significant developments in this area, with a particular focus on asymmetric SOMO- and photoredox-organocatalyzed processes. Over the last 15 years, asymmetric organocatalysis has been growing exponentially. Although mostly based on polar modes of activation, recent important progress has been attained in this field by promoting the formation of, and harnessing the reactivity of, radical intermediates. The resultant merger of organocatalysis with radical chemistry not only has been the key to solve some longstanding bottlenecks, but has also significantly contributed to reinforcing the key role of organocatalysis in the realm of asymmetric catalysis. Provides a thorough overview of the strength of catalytic methodologies Examines the development of asymmetric SOMO- and photoredox-organocatalyzed processes-a rapidly evolving research area Offers a comprehensive but straightforward approach, making the book accessible for non-experts

Book Description :

Considering the limited resources of our planet, earth-abundant elements will have to be explored increasingly in the future. This book highlights the uses of the most earth-abundant elements in catalysis and will be of interest to graduates, academic researchers and practitioners in catalysis.

Book Description :

Corinna Reisinger has developed a new organocatalytic asymmetric epoxidation of cyclic and acyclic α,β-unsaturated ketones. In this thesis, Corinna documents her methodology, using primary amine salts as catalysts, and hydrogen peroxide as an inexpensive and environmentally benign oxidant. She describes the unprecedented and powerful catalytic asymmetric hydroperoxidation of α,β-enones, a process which produces optically active five-membered cyclic peroxyhemiketals in a single operation. She also proves the versatility and synthetic value of the cyclic peroxyhemiketals by converting them into highly enantioenriched acyclic and cyclic aldol products. Currently, these cyclic aldol products are inaccessible by any other synthetic means. Furthermore, cyclic peroxyhemiketals are precursors to optically active 1,2-dioxolanes which are of biological relevance. This work is a breakthrough in the field of asymmetric epoxidation chemistry and outlines the most efficient method in the literature for generating highly enantioselective cyclic epoxyketones known to date.

Book Description :

The Exciplex contains the proceedings of the International Exciplex Conference held at the University of Western Ontario, on May 28-31, 1974. The papers explore various aspects of exciplex behavior and cover topics ranging from singlet- and triplet-state exciplexes to the photophysics of aromatic excimers. Electron-transfer reactions in multicomponent systems are also considered, along with intramolecular triplet-state charge-transfer interactions in aminoketones. Comprised of 15 chapters, this book opens with an overview of the photochemistry of excimers and exciplexes, followed by a discussion on singlet- and triplet-state exciplexes and the photophysics of aromatic excimers. Experimental results on intersystem crossing and ionic recombination processes are then presented, and electronic structures as well as dynamical behavior of some exciplex systems are described. The next chapters focus on excimers of hydrogen and acetone; complexes of dipolar excited states and small polar molecules; electron transfer and exciplex formation from triplet states of anthracene and metalloporphyrins; and exciplexes in electrogenerated chemiluminescence. The final chapter is devoted to intramolecular triplet-state charge-transfer interactions in aminoketones. This monograph will be of interest to chemists and physicists.