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Author: Dylan E. Parsons
Publisher:
ISBN:
Category :
Languages : en
Pages : 306
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Book Description
"Cation-[pi] cyclization cascades of alkylidene [beta]-ketoesters bearing a pendent alkene with various substitution patterns are described. Depending upon the alkene substitution pattern and the reaction conditions employed, it is possible to achieve selective synthesis of the five different types of products, including 1-halo-3-carbomethoxycyclohexanes, spiro-fused tricyclic systems, [4.3.1] bridged bicyclic ring systems, bridged dihydropyrans, and [4.2.2] bridged pyrans and piperidines. All pathways begin with addition of an olefin to the alkylidene [beta]-ketoester electrophile, followed by one of five different cation capture events, to afford each of the unusual polycyclic systems with a high degree of stereocontrol. Herein, work accomplished towards the total synthesis of arnicenone is also reported. Synthesis of a test substrate is described, which was cyclized to examine the proposed key step. After analysis of the key step, the synthetic route was modified to accommodate the results. A racemic synthesis was then attempted which provided small quantities of the key intermediate to be cyclized"--Page viii.
![I. Cationic Cascade Reactions of Alkylidene [beta]-ketoesters PDF](https://books.google.com/books/content/images/frontcover/PNgWzgEACAAJ?fife=w80-h100)
Author: Dylan E. Parsons
Publisher:
ISBN:
Category :
Languages : en
Pages : 306
Get Book Here
Book Description
"Cation-[pi] cyclization cascades of alkylidene [beta]-ketoesters bearing a pendent alkene with various substitution patterns are described. Depending upon the alkene substitution pattern and the reaction conditions employed, it is possible to achieve selective synthesis of the five different types of products, including 1-halo-3-carbomethoxycyclohexanes, spiro-fused tricyclic systems, [4.3.1] bridged bicyclic ring systems, bridged dihydropyrans, and [4.2.2] bridged pyrans and piperidines. All pathways begin with addition of an olefin to the alkylidene [beta]-ketoester electrophile, followed by one of five different cation capture events, to afford each of the unusual polycyclic systems with a high degree of stereocontrol. Herein, work accomplished towards the total synthesis of arnicenone is also reported. Synthesis of a test substrate is described, which was cyclized to examine the proposed key step. After analysis of the key step, the synthetic route was modified to accommodate the results. A racemic synthesis was then attempted which provided small quantities of the key intermediate to be cyclized"--Page viii.
![Exploration of Haloalkylated [beta]-ketoesters in C-C Bond Fragmentation and Radical Cascade Reactions PDF](https://books.google.com/books/content/images/frontcover/GMCnswEACAAJ?fife=w80-h100)
Author: Judith Hierold
Publisher:
ISBN:
Category :
Languages : en
Pages : 308
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Book Description
The development of novel transformations is a key paradigm of synthetic organic chemistry. In order to be of practical significance, ready access to a range of starting materials with broad structural variety is an important consideration when developing new methodologies. The research detailed in this PhD thesis takes advantage of the ubiquity of cyclic [beta]-ketoesters and their ready conversion to the corresponding haloalkylated derivatives, and applies the resultant [beta]-haloalkylated [beta]-ketoesters in C-C bond fragmentation and radical cascade reactions.In the introductory chapter, a short overview of synthetic approaches to cyclic [beta]-ketoesters is given. Their ability to undergo C-alkylation with electrophilic dihaloalkanes is then discussed, followed by an overview of previous synthetic efforts to apply the resultant [beta]-haloalkylated [beta]-ketoesters in organic transformations. It is concluded that, while some attention has been focused on their use in subsequent reactions, a number of avenues for reaction discovery exist that are largely unexplored.In the second chapter of this thesis, Grob-Eschenmoser-type C-C bond fragmentation reactions are introduced. Traditionally, the fragmentation is restricted to small sized ring systems, working efficiently only on cyclopentanones. By inclusion of an electron-withdrawing group in [beta] position to the carbonyl, it is shown that facile C-C bond fragmentation can be achieved with a wide range of nucleophiles, and on cycloalkanones of varying ring size and substitution. Mechanistic studies are conducted, which provide greater support for a concerted Grob fragmentation over a two step retro-Dieckmann/elimination sequence. Application of the fragmentation products to the synthesis of 1,2-dicarbonyls, substituted g-lactones and the side chain of the natural product eriolangin are also discussed.The studies detailed in the third chapter describe the application of the C-C bond fragmentation reaction to the divergent synthesis of dendritic molecules. By iterative C-C bond fragmentation/thio-Michael addition a fourth generation dendrimer is assembled, which is thoroughly characterised. In addition, a number of structurally diverse first and second generation dendrimers are synthesised. Combination of the C-C bond fragmentation with a deprotection step allows for the assembly of internally functionalised AB2C dendrimers. Water solubility is targeted, and found to be best achieved by inclusion of oligoether moieties into the dendritic structure. Efforts to immobilise catalytically active chiral secondary amines onto the dendritic support are then discussed. While a range of first generation organocatalytic dendrimers are synthesised, their performance in the a-amination of aldehydes proceeds with only moderate enantioinduction.In the fourth chapter, the Beckwith-Dowd ring expansion is introduced, a reaction that furnishes ring expanded cycloalkanones from haloalkylated cyclic [beta]-ketoesters. It is demonstrated that radical cascades can be triggered by inclusion of an allylic or propargylic ester substituent, leading to spirocyclic g-lactones. Following reaction development and optimisation, the scope of the cascade with regards to the ester substituent, the cycloalkanone ring size and the length of the haloalkylated side chain are investigated. The chapter concludes with short studies on the application of the cascade reaction to the synthesis of spirocyclic g-lactams or all-carbon spirocycles.The fifth chapter provides a summary of the chemistry detailed in the preceding chapters and outlines future directions for this research project.Finally, the sixth chapter contains experimental procedures utilised within this project and all the spectroscopic data derived from the compounds introduced in the preceding chapters.
Author: Peng-Fei Xu
Publisher: John Wiley & Sons
ISBN: 1118356632
Category : Science
Languages : en
Pages : 442
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Book Description
Demonstrates the advantages of catalytic cascade reactions for synthesizing natural products and pharmaceuticals Riding the wave of green chemistry, catalytic cascade reactions have become one of the most active research areas in organic synthesis. During a cascade reaction, just one reaction solvent, one workup procedure, and one purification step are needed, thus significantly increasing synthetic efficiency. Featuring contributions from an international team of pioneers in the field, Catalytic Cascade Reactions demonstrates the versatility and application of these reactions for synthesizing valuable compounds. The book examines both organocatalysis and transition-metal catalysis reactions, bringing readers up to date with the latest discoveries and activities in all major areas of catalytic cascade reaction research. Catalytic Cascade Reactions begins with three chapters dedicated to organocatalytic cascade reactions, exploring amines, Brønsted acids, and the application of organocatalytic cascade reactions in natural product synthesis and drug discovery. Next, the book covers: Gold-catalyzed cascade reactions Cascade reactions catalyzed by ruthenium, iron, iridium, rhodium, and copper Palladium-catalyzed cascade reactions of alkenes, alkynes, and allenes Application of transition-metal catalyzed cascade reactions in natural product synthesis and drug discovery Engineering mono- and multifunctional nanocatalysts for cascade reactions Multiple-catalyst-promoted cascade reactions All chapters are thoroughly referenced, providing quick access to important original research findings and reviews so that readers can explore individual topics in greater depth. Drawing together and analyzing published findings scattered across the literature, this book provides a single source that encapsulates our current understanding of catalytic cascade processes. Moreover, it sets the stage for the development of new catalytic cascade reactions and their applications.
![Ru/PNNP-catalyzed Asymmetric Diels-Alder and Ficini Reactions on Alkylidene [beta]-ketoesters PDF](https://books.google.com/books/content/images/frontcover/YdUkMwEACAAJ?fife=w80-h100)
Author: Christoph Schotes
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Lutz F. Tietze
Publisher: John Wiley & Sons
ISBN: 3527608680
Category : Science
Languages : en
Pages : 631
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Book Description
Domino reactions enable you to build complex structures in one-pot reactions without the need to isolate intermediates- a dream comes true. In this book, the well-respected expert, Professor Lutz Tietze, summarizes the possibilities of this reaction type - an approach for an efficiant, economically benificial and ecological benign synthesis. A definite must for every organic chemist.
Author: Kengadarane Anebouselvy
Publisher: Royal Society of Chemistry
ISBN: 1782620907
Category : Science
Languages : en
Pages : 220
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Book Description
In the last 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.
Author: Wei Zhang
Publisher: Springer
ISBN: 3030225968
Category : Science
Languages : en
Pages : 49
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Book Description
This book emphasizes the atom economy aspect of multicomponent reactions. It describes how this methodology has been applied to several named reactions. Among the “twelve principles of green chemistry”, atom economy addresses ‘synthetic efficiency’. A multicomponent reaction can be defined as an energy, cost, and time efficient method for organic synthesis. Instead of making one or two bonds in a chemical transformation, multicomponent reactions generate several chemical bonds in a single operation. This book presents a series of detailed reaction mechanisms that beautifully illustrate this principle. Multicomponent reactions are widely applied to the preparation of complex and diverse molecular structures in academic and industrial research laboratories. As such, this book is targeted at researchers involved in green organic chemistry.
Author: Takahiko Akiyama
Publisher: John Wiley & Sons
ISBN: 1119736412
Category : Science
Languages : en
Pages : 798
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Book Description
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: Montserrat Diéguez
Publisher: John Wiley & Sons
ISBN: 3527804072
Category : Technology & Engineering
Languages : en
Pages : 431
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Book Description
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.
Author: Akkattu T. Biju
Publisher: John Wiley & Sons
ISBN: 3527809058
Category : Science
Languages : en
Pages : 440
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Book Description
Summarizing the emerging field of N-heterocyclic carbenes used in organocatalysis, this is an excellent overview of the synthesis and applications of NHCs focusing on carbon-carbon and carbon-heteroatom bond formation. Alongside comprehensive coverage of the synthesis, characteristics and applications, this handbook and ready reference also includes chapters on NHCs for polymerization reactions and natural product synthesis.
