Synthetic and Mechanistic Prospects of Homogeneous Gold Catalysis PDF Download
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Author: Sreekumar Pankajakshan
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: Sreekumar Pankajakshan
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: LeGrande M. Slaughter
Publisher: Springer
ISBN: 3319137220
Category : Science
Languages : en
Pages : 292
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Book Description
The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. 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. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students.
Author: Veronique Michelet
Publisher: World Scientific
ISBN: 1783265558
Category : Science
Languages : en
Pages : 564
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Book Description
Research on designing new catalytic systems has been one of the most important fields in modern organic chemistry. One reason for this is the predominant contribution of catalysis to the concepts of atom economy and green chemistry in the 21st century. Gold, considered catalytically inactive for a long time, is now a fascinating partner of modern chemistry, as scientists such as Bond, Teles, Haruta, Hutchings, Ito and Hayashi opened new perspectives for the whole synthetic chemist community. This book presents the major advances in homogeneous catalysis, emphasizing the methodologies that create carbon-carbon and carbon-heteroatom bonds, the applications that create diversity and synthesize natural products, and the recent advances and challenges in asymmetric catalysis and computational research.It provides readers with in-depth information about homogeneous gold-catalyzed reactions and presents several explanations for the scientific design of a catalyst. Readers will be able to understand the entire gold area and find solutions to problems in catalysis.Gold Catalysis — An Homogeneous Approach is part of the Catalytic Science Series and features prominent authors who are experts in their respective fields.
Author: Lise Molinari
Publisher:
ISBN:
Category :
Languages : en
Pages : 181
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Author: A. Stephen K. Hashmi
Publisher: John Wiley & Sons
ISBN: 3527646884
Category : Science
Languages : en
Pages : 419
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Book Description
With its impressive features, gold has led to completely new reaction types in recent years, which in turn have strongly influenced both organic catalysis and material science. Other fields where a significant amount of new results has been obtained include nanotechnology, self assembly/supramolecular systems and biochemical/medicinal chemistry. As a result, gold is one of the hottest topics in catalysis at the moment, with an increasing amount of research being carried out in this field. While focusing on homogeneous catalysis, this monograph also covers the main applications in heterogeneous catalysis. Following a look at the gold-catalyzed addition of heteroatom nucleophiles to alkynes, it goes on to discuss gold-catalyzed additions to allenes and alkenes, gold-catalyzed benzannulations, cycloisomerization and rearrangement reactions, as well as oxidation and reduction reactions. The whole is finished off with a section on gold-catalyzed aldol and related reactions and the application of gold-catalyzed reactions to natural product synthesis. Of interest to synthetic chemists and inorganic chemists, as well as organic chemists working in homogeneous catalysis, physical and technical chemists.
Author: Manish Kumar
Publisher:
ISBN:
Category : Catalysts
Languages : en
Pages : 185
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Book Description
The focus of my dissertation work was to study the basic mechanistic insights of gold-catalyzed reactions. Although the various mechanistic pathways of gold catalysis are better understood nowadays, numerous questions still remain unanswered concerning the nature of deactivation of the catalyst's active species, high resistance towards protodeauration, and how we can solve these problems to improve the efficiency of gold catalysis. To address these challenges in gold catalysis we conducted first a detailed experimental study to understand the mechanism of deactivation of gold active species. Based on the combination of experimental data, we proposed that gold disproportionation is preferred as compared to reduction of the active gold catalyst. To address the high resistance toward protodeauration, we explored a new strategy to enhance the efficacy of gold-catalyzed reactions through hydrogen-bonding assisted protodeauration using additives chosen for their pKBHX (hydrogen-bond basicity). To address the threshold phenomenon, we observed that high gold affinity impurities (halides, bases) in solvents, starting materials, filtration or drying agents could affect the reactivity of the gold catalyst adversely, which, in turn, may significantly reduce the TON of cationic gold. Use of a suitable acid activator (e.g. HOTf, In(OTf)3) reactivates the gold catalyst and makes the reaction proceed smoothly at low gold catalyst loading. To explore the reactivity of Au catalysts towards oxygen-atom transfer reactions, we investigated the gold-catalyzed addition of O-nucleophiles to alkynes and found that this reaction can produce synthetically important vinyl ether products in excellent yields and regioselectivities at room temperature. At higher temperature, 3,3-sigmatropic rearrangement of vinyl ether products gives access to highly functionalized benzotriazoles.
Author: F. Dean Toste
Publisher:
ISBN: 9781848168534
Category : Catalysis
Languages : en
Pages : 564
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Book Description
Research on designing new catalytic systems has been one of the most important fields in modern organic chemistry, and one reason for this is the predominant contribution of catalysis to the concepts of atom economy and green chemistry in the 21st century. Gold, considered catalytically inactive for a long time, is now a fascinating partner of modern chemistry, as scientists such as Bond, Haruta, Hutchings, Ito and Hayashi opened new perspectives for the whole synthetic chemist community. This book presents the major advances in homogeneous catalysis, emphasizing the methodologies that create carbon-carbon and carbon-heteroatom bonds, the applications that create diversity and synthesize natural products, and the recent advances and challenges in asymmetric catalysis and computational research. The Handbook of Homogeneous Gold Catalysis provides readers with in-depth information about gold-catalyzed reactions and presents several explanations for the scientific design of a catalyst. Readers will be able to understand the entire gold area and find solutions to problems in catalysis. Featuring prominent authors, who are experts in their respective fields, this is the first book dedicated to homogeneous gold chemistry. Contents: From Gold in Nature to Gold Catalysts (S Kramer and F Gagosz); Oxidation and Reduction Reactions (L Zhang); Gold-Catalyzed Addition of Carbon Nucleophile to C-C Multiple Bond (B Simmons and H C Shen); Gold-Catalyzed Addition of Heteroatom Nucleophile to C-C Multiple Bond (N Asao, N Hatakeyama and Y Yamamoto); Gold-Catalyzed Synthesis of Heterocycles (A Arcadi); Multi-Component Reactions (R Skouta and C J Li); Gold Catalyzed Tandem and Cascade Reactions (R-S Liu); Cycloisomerization Reactions of 1, n -Enynes (N Huguet and A Echavarren); Gold-Catalyzed Reaction of Propargylic Esters (L Fensterbank, J-P Goddard, M Malacria and S Simonneau); Gold-Catalyzed Cross-Coupling Reactions (S Blum); Gold-Catalyzed Reactions: A Computational Approach (E Soriano & J Marco-Contelles); Asymmetric Gold-Catalyzed Reactions (P Y Toullec, A Pradal and V Michelet); Gold Catalysis in Natural Product Synthesis (M Gesinski and F D Toste). Readership: Student, professionals.
Author: Zhi Xiang Wong
Publisher:
ISBN:
Category : Alkenes
Languages : en
Pages : 129
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Book Description
Author: Nathan David Shapiro
Publisher:
ISBN:
Category :
Languages : en
Pages : 596
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Book Description
Historically, chemists have been motivated by problems in total synthesis or by a desire to develop reactions of broad utility. In answer to these challenges, several approaches to fundamental research have been developed. In chapter 1, we describe how our reactivity-driven approach has led to the discovery of numerous synthetic tools. The development of new synthetically useful methodology often rests on an understanding of the mechanistic underpinnings of the desired transformation. This is particularly true when this knowledge forms the basis for subsequent mechanistic proposals. The coordination of an alkyne to a cationic Au(I) complex represents the prototypical mechanistic starting place for many Au(I)-catalyzed reactions. In chapter two, we describe the isolation and characterization of a gold(I)-coordinated alkyne. The crystal structure of this compound is compared to related Ag(I) and Cu(I) compounds. With these structures in hand, we can begin to understand the unique ability of Au(I) complexes to serve as effective %pi;-activation catalysts, especially in understanding why gold is often more effective than copper or silver. In addition to being able to activate %pi;-bonds toward nucleophilic attack, it has been proposed that gold is also capable of stabilizing adjacent carbocations. Such species (i.e. [L-Au-CR2]+) have been referred to as gold-carbenoids or gold-stabilized carbocations. In chapter 3, we describe a bonding model for these intermediates that suggests that while the gold-carbon bond order is generally less than or equal to one, this bond includes both %sigma;- and %pi;-type bonding. Furthermore, the position of a given Au-stabilized intermediate on a continuum ranging from gold-stabilized singlet carbene to gold-coordinated carbocation is dictated by both the carbene substituents and the ancillary ligand. This model provides an explanation for observed ancillary ligand effects and should enable more efficient reaction optimization. In chapter 4, a series of gold(I)-catalyzed rearrangement reactions of alkynyl sulfoxides, sulfimides and sulfur ylides are reported. Homopropargyl sulfoxides are rearranged to benzothiepinones or benzothiopines, while %alpha;-thioenones are formed in the reaction of propargyl sulfoxides. It is proposed that these reactions proceed via an %alpha;-carbonyl gold-carbenoid intermediate formed through gold-promoted oxygen atom transfer from sulfoxide to alkyne. In chapter 5, the development of a convenient gold(III)-catalyzed synthesis of azepines from the intermolecular annulation of propargyl esters and %alpha;, %beta;-unsaturated imines is discussed. Mechanistic experiments suggest that this formal [4 + 3]-cycloaddition reaction proceeds via a stepwise process involving intermolecular trapping of a gold-carbenoid intermediate and subsequent intramolecular trapping of the resulting allyl-gold intermediate. In chapter 6, we discuss the gold(III)-catalyzed [3+3]-cycloaddition reaction of propargyl esters and azomethine imines. This reaction provides a rapid entry into a wide range of substituted tetrahydropyridazine derivatives from simple starting materials. A mechanism similar to that proposed in chapter 5 is discussed, along with a detailed description of the consequences of this mechanism on the diastereoselectivity of the annulation reaction. In addition, a strategy for rendering this reaction asymmetric is presented.
Author: Yanzhao Wang
Publisher:
ISBN: 9781321203318
Category :
Languages : en
Pages : 285
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Book Description
In the past dozen years, great progress has been made in developing highly efficient homogenous gold catalysis. As soft "pi" Lewis acids, cationic gold(I) complexes are particularly powerful in terms of activating alkyne/allene towards nucleophilic attack, leading to a variety of synthetically versatile structures. During my research, several synthetic methods have been developed, including: (1) Au-catalyzed ligand-directed anti nucleophilic attack of alkynes; the new ligands I developed enable highly efficient gold-catalyzed nucleophilic addition of acids, anilines and water to the alkynes; and catalyst loadings could be lowered to 10 parts per million; (2) rapid access of chroman-3-ones via gold-catalyzed oxidation of propargyl aryl ethers; this step-economic and efficient transformation was realized by a bulky gold catalyst, Me4tBuXPhosAuNTf2 and bulky electron-deficient pyridine N-oxides derived from Hantzsch esters; (3) Au-catalyzed novel indole synthesis via a key [3,3] sigmatropic rearrangement; 2-alkylindoles were produced with high regioselectivity and efficiency from easily accessed N-arylhydroxylamines under mild conditions; an improved approach involved cooperative dual catalysis of Zn and Au was developed; much broader substrate scope, shorter reaction time and good to excellent yields were achieved.
