Development Of Anion Binding Approaches To Asymmetric Catalysis

The dual catalytic approach in asymmetric catalysis has gained considerable attention in recent times. Many otherwise inefficient and unattainable chemical processes can be accomplished by this approach. Outlined within this dissertation are recent efforts in improving the overall efficiency of this process as well as expanding this method involving nucleophilic/anion-binding catalysis to the kinetic resolution of allylic amines and 1,2-diamines. An efficient catalytic system has been identified through targeted structural modifications of both the achiral nucleophilic catalyst and the chiral anion-binding co-catalyst. This has resulted in increased selectivities while simultaneously allowing for significantly reduced catalyst loadings. Based on the mechanistic insight into the anion binding approach for the kinetic resolution of amines, we established that there was a 1:1 catalyst to benzoate anion binding ratio. Cooperative approaches in which Brønsted acids act in concert with other Brønsted acids or (thio) urea co-catalysts have gained significance. This study describes the synthesis of a new class of chiral conjugate-base-stabilized Brønsted acid catalysts and a new concept for cooperative hydrogen bonding/ Brønsted acid catalysis. These chiral Brønsted acids contain a carboxylic acid group which is connected via an appropriate linker to an anion receptor moiety such as a thiourea. Substrate protonation by the catalyst results in the association of the conjugate base with the anion recognition site, resulting in the formation of a rigid catalyst/substrate ion pair. We were able to successfully apply this concept to the catalytic enantioselective Povarov and Pictet-Spengler reactions.

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.

Anion recognition plays a critical role in a range of biological processes, and a variety of receptors and carriers can be found throughout the natural world. Chemists working in the area of supramolecular chemistry have created a range of anion receptors, drawing inspiration from nature as well as their own inventive processes. This book traces the origins of anion recognition chemistry as a unique sub-field in supramolecular chemistry while illustrating the basic approaches currently being used to effect receptor design. The combination of biological overview and summary of current synthetic approaches provides a coverage that is both comprehensive and comprehensible. First, the authors detail the key design motifs that have been used to generate synthetic receptors and which are likely to provide the basis for further developments. They also highlight briefly some of the features that are present in naturally occurring anion recognition and transport systems and summarise the applications of anion recognition chemistry. Providing as it does a detailed review for practitioners in the field and a concise introduction to the topic for newcomers, Anion Receptor Chemistry reflects the current state of the art. Fully referenced and illustrated in colour, it is a welcome addition to the literature.

This second edition of the pioneering work on this hot topic captures the major trends and latest achievements in the art of asymmetric catalysis on an industrial scale. A number of completely new real-life case studies written by the world leaders in their respective areas provide a compact and qualified insight into this developing field. The resulting ready reference and handbook collates first-hand and valuable information within a context where it can be easily found. The high-quality contributions illustrate the relevant environments and situations, such as time pressure, how the catalytic step fits into the overall synthesis, or competition with other synthetic approaches, as well as the typical problems encountered in the various phases, including finding/developing the catalyst and optimization of the process or choice of equipment. Both successful and unsuccessful approaches to solve these problems are described.

In Chapters 1, we provide an overview of the progress and challenges in the development of enantioselective halo- and seleno-functionalization reactions, which proceed via three-membered ring cationic halonium or seleniranium ions.

This book covers advances in the methods of catalytic asymmetric synthesis and their applications. Coverage moves from new materials and technologies to homogeneous metal-free catalysts and homogeneous metal catalysts. The applications of several methodologies for the synthesis of biologically active molecules are discussed. Part I addresses recent advances in new materials and technologies such as supported catalysts, supports, self-supported catalysts, chiral ionic liquids, supercritical fluids, flow reactors and microwaves related to asymmetric catalysis. Part II covers advances and milestones in organocatalytic, enzymatic and metal-based mediated asymmetric synthesis, including applications for the synthesis of biologically active molecules. Written by leading international experts, this book consists of 16 chapters with 2000 References and illustrations of 560 schemes and figures.

Supramolecular Catalysis Provides a timely and detailed overview of the expanding field of supramolecular catalysis The subdiscpline of supramolecular catalysis has expanded in recent years, benefiting from the development of homogeneous catalysis and supramolecular chemistry. Supramolecular catalysis allows chemists to design custom-tailored metal and organic catalysts by devising non-covalent interactions between the various components of the reaction. Edited by two world-renowned researchers, Supramolecular Catalysis: New Directions and Developments summarizes the most significant developments in the dynamic, interdisciplinary field. Contributions from an international panel of more than forty experts address a broad range of topics covering both organic and metal catalysts, including emergent catalysis by self-replicating molecules, switchable catalysis using allosteric effects, supramolecular helical catalysts, and transition metal catalysis in confined spaces. This authoritative and up-to-date volume: Covers ligand-ligand interactions, assembled multi-component catalysts, ligand-substrate interactions, and supramolecular organocatalysis and non-classical interactions Presents recent work on supramolecular catalysis in water, supramolecular allosteric catalysis, and catalysis promoted by discrete cages, capsules, and other confined environments Highlights current research trends and discusses the future of supramolecular catalysis Includes full references and numerous figures, tables, and color illustrations Supramolecular Catalysis: New Directions and Developments is essential reading for catalytic chemists, complex chemists, biochemists, polymer chemists, spectroscopists, and chemists working with organometallics.

In this most up-to-date handbook each chapter contains a general introduction, followed by the principles of the immobilization and, finally, applications. In this way, it covers the most important approaches currently employed for the heterogenization of chiral catalysts, including data tables, applications, reaction types and literature citations. For chemists in both academia and industry as well as those working in the fine chemical and pharmaceutical industry.

Praise for the previous editions "An excellent text . . . will no doubt provide the benchmark for comparative works for many years." —Journal of the American Chemical Society "An excellent state-of-the-art compilation of catalytic asymmetric chemistry . . . should be included in any chemistry reference collection." —Choice "This is a tremendous resource and an excellent read. I recommend immediate purchase." —Perkin Transactions Since this important work was first published in 1993, the field of catalytic asymmetric synthesis has grown explosively, spawning effective new methods for obtaining enantiomerically pure compounds on a large scale and stimulating new applications in diverse fields—from medicine to materials science. Catalytic Asymmetric Synthesis, Third Edition addresses these rapid changes through contributions from highly recognized world leaders in the field. This seminal text presents detailed accounts of the most important catalytic asymmetric reactions known today, and discusses recent advances and essential information on the initial development of certain processes. An excellent working resource for academic researchers and industrial chemists alike, the Third Edition features: Six entirely new chapters focusing on novel approaches to catalytic asymmetric synthesis including non-conventional media/conditions, organocatalysis, chiral Lewis and Bronsted acids, CH activation, carbon-heteroatom bond-forming reactions, and enzyme-catalyzed asymmetric synthesis A new section focusing on the important new reaction, asymmetric metathesis, in carbon-carbon bond-forming reactions Updated chapters on hydrogenation, carbon-carbon bond-forming reactions, hydrosilylations, carbonylations, oxidations, amplifications and autocatalysis, and polymerization reactions Retaining the best of its predecessors but now thoroughly up to date, Catalytic Asymmetric Synthesis, Third Edition serves as an excellent desktop reference and text for researchers and students from the upper-level undergraduates through experienced professionals in industry or academia.

The second supplement to the three volume reference work Comprehensive Asymmetric Catalysis critically reviews new developments to the hottest topics in the field written by recognised experts. Seven chapters which are already in the major reference work have been supplemented and additionally a new chapter on Aminohydroxylation of Carbon-Carbon Double Bonds has been included. Thus, the state of the art in this area is now re-established. Together with the basic three volume book set and Supplement 1 it is not only the principal reference source for synthetic organic chemists, but also for all scientific researchers who use chiral compounds in their work (for example, in biochemical investigations and molecular medicine) as well as for pharmaceutical chemists and other industrial researchers who prepare chiral compounds.