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Author: Jakob Schneider Publisher: Cuvillier Verlag ISBN: 3736935439 Category : Science Languages : en Pages : 276
Book Description
This thesis focuses on the first synthesis and application of planar-chiral [2.2]paracyclophane- derived hydrogen-bond donor catalysts, thereby inducing a unique chiral motif into the emerging field of thiourea organocatalysis. Reaction acceleration through hydrogen-bond catalysis has made a significant impact on the field, rendering the development of potent catalyst structures extremely valuable. Based on the [2.2]paracyclophane scaffold, mono- and bi-functional thiourea catalysts were prepared. The rigidity of the [2.2]paracyclophane structure leads to a unique setup of the substituents. In pseudo-geminal position to the thiourea moiety, a hydroxy group was selected and introduced as the second functionality. In a 12-step synthesis, the enantiopure hydroxy- substituted [2.2]paracyclophanylene thiourea was obtained. Furthermore, efficient access to enantiopure pseudo-geminally substituted 13-amino-4- bromo[2.2]paracyclophane was developed. The aminobromide was employed in cross- coupling reactions to yield arylated amino[2.2]paracyclophanes, exhibiting a broad range of electronic and steric features useful for organocatalytic applications. The developed catalysts were applied in asymmetric organic transformations and proved most useful in the transfer hydrogenation reaction. The hydroxy-substituted thiourea catalyst particularly exhibited catalytic activity and stereoselectivity. To shed light on the mode of action of this class of hydrogen-bond catalysts, various analytic methods were conducted. Through extensive crystallographic and NMR complexation experiments, the binding properties of the catalysts were investigated in terms of their interaction with hydrogen-bond- accepting functional groups. Furthermore, quantum chemical DFT and ab initio calculations were undertaken to explore the favored conformations of [2.2]paracyclophane-derived thioureas. The combined findings revealed substrate-dependent activation via single or double hydrogen bonding between the NH groups of the thiourea and the respective substrate. Furthermore, a class of readily accessible hydrogen-bond thiourea catalysts was developed, derived from amino acids. Their steric and electronic features were modulated by their degree of substitution at the carbinol carbon center. All catalysts were applied in the asymmetric transfer hydrogenation of nitroolefins, furnishing the products in up to 99% yield and 87% enantiomeric excess.
Author: Jakob Schneider Publisher: Cuvillier Verlag ISBN: 3736935439 Category : Science Languages : en Pages : 276
Book Description
This thesis focuses on the first synthesis and application of planar-chiral [2.2]paracyclophane- derived hydrogen-bond donor catalysts, thereby inducing a unique chiral motif into the emerging field of thiourea organocatalysis. Reaction acceleration through hydrogen-bond catalysis has made a significant impact on the field, rendering the development of potent catalyst structures extremely valuable. Based on the [2.2]paracyclophane scaffold, mono- and bi-functional thiourea catalysts were prepared. The rigidity of the [2.2]paracyclophane structure leads to a unique setup of the substituents. In pseudo-geminal position to the thiourea moiety, a hydroxy group was selected and introduced as the second functionality. In a 12-step synthesis, the enantiopure hydroxy- substituted [2.2]paracyclophanylene thiourea was obtained. Furthermore, efficient access to enantiopure pseudo-geminally substituted 13-amino-4- bromo[2.2]paracyclophane was developed. The aminobromide was employed in cross- coupling reactions to yield arylated amino[2.2]paracyclophanes, exhibiting a broad range of electronic and steric features useful for organocatalytic applications. The developed catalysts were applied in asymmetric organic transformations and proved most useful in the transfer hydrogenation reaction. The hydroxy-substituted thiourea catalyst particularly exhibited catalytic activity and stereoselectivity. To shed light on the mode of action of this class of hydrogen-bond catalysts, various analytic methods were conducted. Through extensive crystallographic and NMR complexation experiments, the binding properties of the catalysts were investigated in terms of their interaction with hydrogen-bond- accepting functional groups. Furthermore, quantum chemical DFT and ab initio calculations were undertaken to explore the favored conformations of [2.2]paracyclophane-derived thioureas. The combined findings revealed substrate-dependent activation via single or double hydrogen bonding between the NH groups of the thiourea and the respective substrate. Furthermore, a class of readily accessible hydrogen-bond thiourea catalysts was developed, derived from amino acids. Their steric and electronic features were modulated by their degree of substitution at the carbinol carbon center. All catalysts were applied in the asymmetric transfer hydrogenation of nitroolefins, furnishing the products in up to 99% yield and 87% enantiomeric excess.
Author: Peter I. Dalko Publisher: John Wiley & Sons ISBN: 3527658882 Category : Science Languages : en Pages : 1499
Book Description
Structured in three parts this manual recollects efficient organocatalytic transformations around clear principles that meet actual standard in asymmetric synthesis. Chapters were written by acknowledged leaders of the organocatalysis field, and are presented in a concise way. Volume 1: Privileged Catalysts gives insight to readers to the continuously increasing variety of catalysts, and the relatively complex interactions that make organocatalytic reactions selective. An appendix recollects catalyst structures with the adequate cross-references. Volume 2: Activations covers the fundamental activation types (non-covalent and covalent activations) and helps understanding the importance of physical parameters, and in particular, the role of water, that influences reactivity and selectivity. Volume 3: Reactions and Applications highlights transformations by reaction types. The final part of this volume is dedicated to application in multistep synthesis and industrial applications. Considering the ever increasing interest in the organocatalysis field, the book aims addressing to a large audience: to academic, and, industrial researchers, students and teachers who are interested in synthetic organic chemistry at advanced level. This book provides non-specialists with an introduction to the topic as well as serving as a valuable source for newcomers and researchers searching for an up-to-date and comprehensive overview of this promising area of synthetic organic chemistry.
Author: Richard B. Silverman Publisher: Elsevier ISBN: 0080513360 Category : Technology & Engineering Languages : en Pages : 736
Book Description
The Organic Chemistry of Enzyme-Catalyzed Reactions is not a book on enzymes, but rather a book on the general mechanisms involved in chemical reactions involving enzymes. An enzyme is a protein molecule in a plant or animal that causes specific reactions without itself being permanently altered or destroyed. This is a revised edition of a very successful book, which appeals to both academic and industrial markets. Illustrates the organic mechanism associated with each enzyme-catalyzed reaction Makes the connection between organic reaction mechanisms and enzyme mechanisms Compiles the latest information about molecular mechanisms of enzyme reactions Accompanied by clearly drawn structures, schemes, and figures Includes an extensive bibliography on enzyme mechanisms covering the last 30 years Explains how enzymes can accelerate the rates of chemical reactions with high specificity Provides approaches to the design of inhibitors of enzyme-catalyzed reactions Categorizes the cofactors that are appropriate for catalyzing different classes of reactions Shows how chemical enzyme models are used for mechanistic studies Describes catalytic antibody design and mechanism Includes problem sets and solutions for each chapter Written in an informal and didactic style
Author: Michael Gregorio Rombola Publisher: ISBN: 9780438088542 Category : Languages : en Pages : 404
Book Description
Chiral hydrogen-bond donor molecules have emerged as powerful catalysts for asymmetric organic synthesis. Principles of hydrogen-bond donor catalyst design have led to the development of thiosquaramides and bispyridiniums as highly active catalysts. The synthesis and catalytic performance of thiosquaramide and bispyridinium catalophores is described, as well as their application to new methodologies, in particular highly enantioselective Michael additions of barbituric acids to nitroalkenes and nitro-Diels-Alder reactions.
Author: Peter I. Dalko Publisher: John Wiley & Sons ISBN: 3527610952 Category : Science Languages : en Pages : 559
Book Description
In this reference leaders at the forefront of research provide an insight into one of the hottest topics in organic synthesis, focusing on the most important enantioselective reactions. Clearly structured, each entry begins with a concise introduction, including a mechanistic discussion of the reaction, followed by preparative guidelines for newcomers, such as carefully selected working procedures with critical notes for bench chemists, rules of thumb and tips and tricks.
Author: Petri M. Pihko Publisher: John Wiley & Sons ISBN: 3527627855 Category : Science Languages : en Pages : 395
Book Description
This first comprehensive overview of the rapidly growing field emphasizes the use of hydrogen bonding as a tool for organic synthesis, especially catalysis. As such, it covers such topics as enzyme chemistry, organocatalysis and total synthesis, all unified by the unique advantages of hydrogen bonding in the construction of complex molecules from simple precursors. Providing everything you need to know, this is a definite must for every synthetic chemist in academia and industry.
Author: Olga Garcia-Mancheno Publisher: John Wiley & Sons ISBN: 3527348573 Category : Technology & Engineering Languages : en Pages : 418
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.
Author: Paul C J Kamer Publisher: Royal Society of Chemistry ISBN: 1849739900 Category : Science Languages : en Pages : 897
Book Description
Providing an integrated approach to the various aspects of catalysis, this textbook is ideal for graduate students from catalysis, engineering, and organic synthesis.
Author: Jakob Schneider
Author: Jakob Schneider
Author: Jakob Schneider![Planar Chiral [2.2] Paracyclophanediols as Metal-free Hydrogen-bonding Organocatalysts PDF](https://books.google.com/books/content/images/frontcover/9RMdjwEACAAJ?fife=w80-h100)
Author: 
Author: Peter I. Dalko
Author: Richard B. Silverman
Author: Michael Gregorio Rombola
Author: Peter I. Dalko
Author: Petri M. Pihko
Author: Olga Garcia-Mancheno
Author: Paul C J Kamer