Download or read book Palladium catalyzed Carbon hydrogen Bond Functionalization Utilizing an Exo directing Strategy written by Zhi Ren (Ph. D.) and published by . This book was released on 2016 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal catalyzed functionalization of carbon-hydrogen bonds (C−H bonds) has become an exponentially growing field. Particularly, Pd-catalyzed methods with various directing groups (DGs) have been developed for site selectivity. In addition, the use of an oxime as a DG proved to be an efficient and removable DG. However, alcohol-based directing strategies are still rare and underdeveloped. The research and development in this dissertation mainly focused on the utilization of masked alcohols as DGs for late stage diversification. With an exo-directing strategy, the syntheses of chemically differentiated vicinal diols and 2-hydroxyalkylphenol derivatives were achieved. Through a series of studies on cyclopalladation of methine groups, the first direct C−H activation complex was prepared and characterized. Additionally, a comprehensive introduction of TM-catalyzed alkylation of aromatic C−H bonds with simple olefins was illustrated.
Download or read book Strategies for Palladium Catalyzed Non directed and Directed C bond H Bond Functionalization written by Anant R. Kapdi and published by Elsevier. This book was released on 2017-05-23 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Strategies for Palladium-Catalyzed Non-directed and Directed C-H Bond Functionalization portrays the complete scope of these two aspects of C-H bond functionalization in a single volume for the first time. Featured topics include the influence of palladacyclic systems in C-H bond functionalization (need for newer catalytic systems for better efficiency), mechanistic aspect of the functionalization strategies leading to better systems, and applications of these methodologies to natural product synthesis and material synthesis. Addresses the involvement of catalytic systems (palladacycles) for better functionalization of (hetero)arenes to emphasize the need for developing better, more selective systems Covers the use of powerful mechanistic tools for understanding and assisting the development of better functionalization strategies Discusses the finer aspects of C-H bond functionalization, such as control of regioselectivity with or without directing groups Includes a chapter detailing the synthesis of naturally occurring molecules or functional molecules via both pathways for assessing the applicability of the functionalization strategies
Download or read book Sustainable C sp3 H Bond Functionalization written by Jin Xie and published by Springer. This book was released on 2016-02-29 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights major achievements made in the last five years concerning sustainable C(sp3)-H bond functionalization and offers a promising and emerging tool-kit for organic synthesis. The book is divided into three chapters demonstrating key advances in C(sp3)-H bond functionalization. Chapter 1 reviews transition-metal-catalyzed C(sp3)-H bond functionalization using different directing groups, while Chapter 2 addresses the new methods of transition-metal-catalyzed and metal-free C(sp3)-H bond functionalization without directing groups, in addition to briefly highlighting redox-neutral C(sp3)-H bond functionalization. In closing, Chapter 3 examines visible-light photoredox catalysis, an emerging and highly sustainable C(sp3)-H bond functionalization strategy. The book offers an intriguing and useful reference guide for a broad readership working and/or interested in the fields of organic, organometallic, and green chemistry.
Download or read book Advances in Palladium catalyzed Carbon carbon Bond Formation Via Functionaliszaton of Carbon hydrogen Bonds written by Olivier René and published by . This book was released on 2010 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Part A written by David Lapointe and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigations in Iron Copper and Palladium catalyzed C H Bond Functionalization written by Ly Dieu Tran and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal-catalyzed functionalization of C-H bonds has been used as a powerful tool for the construction of C-C and C-heteroatom bonds. Within this dissertation, methods that allow functionalization of C-H bonds via iron and copper catalysis have been developed. Additionally, functionalization of sp3 C-H bonds in amino acid derivatives using auxiliary-assisted palladium-catalyzed methodology is also demonstrated. A method for iron-catalyzed alkylation of arenes and heterocycles containing acidic C-H bonds has been developed. Various heterocycles such as pyridine, furan, thiophene and electron deficient arenes can be coupled with both alkyl bromides and iodides. Magnesium amide base is required for the reaction. Similarly, the deprotonative dimerization of arenes and heterocycles can be effected in the presence of an iron catalyst. Thus, the method allows direct functionalization of arenes and heterocycles. Additionally, the use of an iron catalyst is an advantage compared with existing methods. Methods for copper-catalyzed direct sulfenylation and amination of sp2 C-H bonds have been developed. Using 8-aminoquinoline auxiliary and copper catalyst, ortho C-H bonds of benzoic acid amides can be sulfenylated by disulfides. The method provides an alternative, milder way for the preparation of aryl trifluoromethylsulfides. Furthermore, ortho C-H bonds of benzoic acid amides can be aminated by reaction with simple amines using 8-aminoquinoline directing group and a copper catalyst. Sulfenylation and amination of g-C-H bonds of benzyl amine derivatives using picolinic acid auxiliary were also demonstrated. Broad substrate scope, high regioselectivity, and good functional group tolerance were observed. The use of a copper catalyst and a removable directing group are significant improvements compared with the existing methods. Finally, a novel way for synthesis of non-natural amino acids via auxiliary-assisted, palladium-catalyzed C-H functionalization methodology was developed. Under palladium catalysis, 2-methyl thioaniline auxiliary allows the monoarylation of b-C-H bonds of alanine derivatives generating, after directing group removal, substituted phenylalanines. In contrast, using 8-aminoquinoline auxiliary, methylene groups in phenylalanine, leucine, and lysine derivatives can be arylated. Methods for alkylation and acetoxylation were also reported. The directing group can be removed without significant erosion of enantiomeric excess. The method provides a straight-forward way to synthesize non-natural amino acids from the chiral pool.
Download or read book Transition Metal catalyzed Functionalization of Carbon hydrogen Bonds in Alkenes written by Xiaolin Qian and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Alkenes can undergo a variety of chemical reactions to form more complex molecules with a range of functional groups. This makes them useful starting materials for synthesizing a wide range of organic compounds. Chapter I provided an overview of the development history of alkenyl C8́2H bond activation. The early reactions of C8́2H compounds with metal complexes, as well as stoichiometric activation of the transition metal-activated C-H bond, were discussed. Then the first successful and efficient organometallic-catalyzed transformations of a C8́2H bond, the first transition metal-catalyzed vinylic C-H functionalization, and the first transition metal-catalyzed olefinic C-H functionalization under mild conditions were demonstrated. Finally, enantioselective vinylic C-H functionalization was discussed. In Chapter II, a method for enantioselective vinylic C(sp2)8́2H bond activation using a Ru(II) catalyst and a chiral transient directing group was developed. Chiral amine was also utilized to control the Z/E stereoselectivity. The method demonstrated a broad substrate scope with good yield, high Z/E ratio stereoselectivity, and excellent enantioselectivity. Its synthetic utility was demonstrated by the synthesis of key structural motifs of particularly useful natural products and pharmaceutical compounds. Additionally, a rare vinylic C8́2H bond activated ruthenic complex was isolated and determined by single-crystal X-ray diffraction. The methodology suggested in this work is expected to facilitate the further development of asymmetric vinylic C8́2H functionalization reactions. In Chapter III, a practical and efficient methodology for Ru(II)-catalyzed enantioselective alkenyl C-H bond functionalization of indole-substituted acrylaldehyde derivatives via the chiral transient directing group (CTDG) strategy to obtain optically active pyrrolo[1,2-a]indole derivatives was suggested. The methodology resulted in a series of optically active products with good yields (up to 80%), good stereoselectivity (up to 25.0:1 Z/E), and excellent enantioselectivity (up to 95% ee). Furthermore, synthetic transformations were explored. Chapter IV presented the first demonstration of a sequentially composed catalytic substitution reaction of alkenes for building multi-amido methylated derivatives while reserving the Ï0- components. The process involved a simple Fe (III)-catalyst and bisamidomethane reagent, which directly and selectively transformed Îł-substituted styrenes into several biologically and pharmaceutically relevant N-heterocycles through tandem processes.
Download or read book Weak Coordination as a Powerful Means for Developing Useful Palladium II catalyzed C H Activation Reactions written by Tian-Sheng Mei and published by . This book was released on 2011 with total page 846 pages. Available in PDF, EPUB and Kindle. Book excerpt: Achieving direct and selective functionalization of carbon-hydrogen (C-H) bonds to give carbon-carbon (C-C) or carbon-heteroatom (C-Y) bonds is a significant and long-standing goal in chemistry. C-H bonds are attractive reaction partners because they are ubiquitous in organic molecules. Thus, C-H functionalization methods could potentially expedite the synthesis of target molecules by providing new disconnections in retrosynthetic analysis. Among the numerous methods to affect this transformation, palladium-catalyzed C-H functionalization is one of most promising methods to construct C-C and C-Y bonds in term of versatile reactivity. The major challenges of palladium-catalyzed C-H functionalization are developing reactions that work with common and useful structural motifs and discovering new transformation, such as C-N or C-F bond formation. This thesis explores palladium-catalyzed C-H bond functionalization with substrates containing simple functional groups such as carboxylic acids and triflamides, which direct C-H cleavage through weak coordination with the metal catalyst. Chapter one introduces different types of C-H bond functionalization and focuses on Pd(II)/Pd(IV) catalysis. Chapter two covers Pd-catalyzed C-H iodination of arene carboxylic acids enabled by the discovery of coutercation-promoted C-H activation. Weak coordination has also been found to enable versatile reactivity of simple arene carboxylic acids. Chapter three focuses on the development of practical and useful C-H fluorination using triflamide as a weakly coordinating directing group that can be easily manipulated to a wide range of useful and common aryl halides. Chapter four describes applications of bystanding F+ oxidants to promote selective C-N reductive elimination in Pd(II)/Pd(IV) catalysis.
Download or read book Chelation assisted Palladium catalyzed Activation of C H Bonds written by Ramesh Giri and published by . This book was released on 2009 with total page 1280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon-hydrogen (C-H) bonds are ubiquitous in organic molecules. Utilization of such abundant chemical moieties as functional group equivalents could shorten route to synthetic targets and provide chemists with new disconnections in retrosynthesis. As such regio- and stereoselective functionalization of unactivated C-H bonds has remained one of the major challenges in organic chemistry. The majority of the transition metals have been rigorously examined for their efficacy in transforming unactivated C-H bonds (pKa >35) into useful functional groups or into C-C bonds. Among those metals, palladium is particularly effective in activating both aromatic (sp2) and aliphatic (sp3) C-H bonds. This thesis explores the reactivity of palladium catalysts in both of these areas. The research herein was conducted using directing groups for C-H cleavage with special focus on utilizing simple functionality such as carboxylic acids. Chapter one details different types of directing groups and their utility in a variety of reactions. Chapters two and three contain details of research on C-heteroatom (C-I and C-O) and C-C bond formation, respectively, with palladium acetate as a catalyst. The iodination and acetoxylation reactions proceed under mild conditions and moderate to excellent levels of diastereoselectivity (up to 99.9%) have been observed with both sp2 and sp3 C-H bonds using oxazoline as the directing group. Mechanistic investigations have been carried out in order to understand the high level of stereoselection and, in this process, a number of palladacycle intermediates have been characterized by X-ray crystallography which led us to assign the absolute stereochemistry of C-H activation. Moreover, the iodination protocol could also be extended to prepare diiodides as intermediates for cyclopropanation which provides a new disconnection approach to construct cyclopropanes. Chapter two discusses C-C bond formation via cross-coupling reactions with organoboron reagents and carbon monoxide using the carboxylic acids as the directing group. Detailed mechanistic investigation along with characterization of intermediate palladacycle formed from sodium toluate have revealed an unprecendented directing ability of carboxylate groups in which the carbonyl oxygen, rather than the O-anion, directs palladium for C-H cleavage.
Download or read book C H Bond Activation and Catalytic Functionalization I written by Pierre H. Dixneuf and published by Springer. This book was released on 2015-12-18 with total page 269 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Organometallic Chemistry presents critical overviews of research results in organometallic chemistry. As our understanding of organometallic structure, properties and mechanisms increases, new ways are opened for the design of organometallic compounds and reactions tailored to the needs of such diverse areas as organic synthesis, medical research, biology and materials science. Thus the scope of coverage includes a broad range of topics of pure and applied organometallic chemistry, where new breakthroughs are being achieved that are of significance to a larger scientific audience. The individual volumes of Topics in Organometallic Chemistry are thematic. Review articles are generally invited by the volume editors. All chapters from Topics in Organometallic Chemistry are published OnlineFirst with an individual DOI. In references, Topics in Organometallic Chemistry is abbreviated as Top Organomet Chem and cited as a journal.
Download or read book Palladium Catalyzed Carbon carbon Bond Formation at Carbon hydrogen Bonds written by Louis-Charles Campeau and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The biaryl core has been identified by medicinal chemists as a privileged structure in pharmaceutical compounds as it is found in 4.3% of all drugs. For over a century, synthetic chemists have sought new methods for their preparation. Breakthroughs in synthetic catalytic methodology over the past thirty years gave rise to now routine reactions such as the Suzuki and Stille couplings. Unfortunately, the need for pre-activation of both coupling partners makes for wasteful installation and subsequent removal of activating agents. Direct arylation reactions are attractive alternatives to traditional cross-coupling methods, as one of the pre-activated partners is replaced with a simple arene. The organometallic coupling partner is typically replaced as it is the most difficult to prepare. Although the advantages of this approach have made it a popular research topic for more than twenty-five years, no general catalysts exist for this transformation, and in a lot of cases reactivity remains a challenge. This thesis will outline our work in this area of research. First, our efforts toward the development of a general catalyst for the intramolecular direct arylation of aryl halides with simple arenes will be presented. These studies led to the development of three new catalysts for this transformation, affording a process general for aryl chlorides, bromides and iodides. Additionally, mechanistic studies performed on this system have brought to the forefront the concerted metallation-deprotonation mechanistic model for direct arylation. Ultimately, these studies led to the first non-directed intermolecular direct arylation of a simple arene. In a second section, efforts toward the inclusion of pi-deficient heteocycles as a substrate class in direct arylation will be outlined. These studies led to the development of a novel cross-coupling reaction of azine N-oxides with aryl halides. Greater mechanistic understanding, made possible through the use of computational tools, was crucial in extending this methodology to azole N-oxides. Finally, the development of novel direct functionalization reactions with picoline derivatives is described. These substrates are among the first to be suitable for catalyst controlled site-selective functionalization of a sp2 or sp3 C-H bond.
Download or read book Palladium catalyzed C H Bond Functionalization of Heterocycles and Amines written by Enrico Tapire Nadres and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Palladium-catalyzed functionalization of C-H bonds is becoming an important synthetic tool that allows the preparation of desired substances in fewer steps and higher yields compared to traditional synthetic routes. The C-H bonds can be directly converted to C-C or C-heteroatom bonds. However, the ubiquity of C-H bonds in organic compounds can lead to problems in chemo- and regioselectivity. In heterocycles, the control of regioselectivity of the reaction is governed by the difference in acidity of the heterocyclic ring C-H bonds. An economical method for the arylation of C-H bonds of pyrroles and furans by aryl chlorides was developed. The method employs a palladium acetate catalyst, 2-(dicyclohexylphosphino)biphenyl ligand, and an inorganic base. Electron-rich, electron-poor, and heterocyclic aryl chloride coupling partners can be used and arylated heterocycles are obtained in moderate to good yields. The functionalization of sp2 and sp3 C-H bonds can be promoted by the use of directing groups that coordinate the Pd catalyst and activate the desired C-H functionalities. Use of Pd(OAc)2 in conjunction with cesium acetate or potassium carbonate bases allows functionalization of sp2 and sp3 C-H bonds in amides possessing picolinic acid directing group. Stoichiometric silver additive is not required in contrast with previously published procedure. Arylations are effective for sp2 as well as primary and secondary sp3 C-H bonds. Alkylations of sp2 C-H bonds are successful in most cases. Both primary and secondary alkyl iodides are reactive but secondary alkyl iodides afford low yields. Alkylation of sp2 C-H bonds is low yielding and the reaction requires further optimization. Alkyl and aryl iodides as well as benzyl bromides are reactive. Aryl and alkyl bromides afford no product. Direct conversion of C-H bonds to C-N bonds was also developed. Pd-catalyzed method for pyrrolidine, indoline, and isoindoline formation by cyclization via C-H/N-H coupling is presented. The method employs a picolinamide directing group, PhI(OAc)2 oxidant, and toluene solvent at 80-120 °C. Cyclization is effective for sp2 as well as aliphatic and benzylic sp3 C-H bonds.
Download or read book Cross coupling Reactions written by Joffrey Vrijdag and published by . This book was released on 2020 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Cross-Coupling Reactions: An Overview opens with an overview of the fundamentals and applications of the young and fast developing area of transition metal catalyzed/mediated oxidative (dehydrogenative) C-H/C-H coupling reactions between two (hetero)arenes. Continuing, the authors highlight the recent advances regarding the ligand supported transition metal-catalyzed domino (cascade) or one-pot syntheses of various heterocycles involving cross-coupling reactions. The recent advances in Cu catalyzed tandem reactions for heterocycle synthesis are also addressed. Cu metal chemistry has garnered attention as a potential alternative to precious transition metals, being cheaper, more sustainable and more easily available. A comprehensive account of research on green chemical routes is provided, involving various palladium metal-based catalysts utilized in facilitating cross-coupling reaction in aqueous media. Reported decarboxylative cross-coupling reactions are discussed along with suitable examples, focusing on their mechanism of action"--
Download or read book Dienamine Catalysis for Organic Synthesis written by Kengadarane Anebouselvy and published by Royal Society of Chemistry. This book was released on 2018-03-02 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Artificial Metalloenzymes and MetalloDNAzymes in Catalysis written by Montserrat Diéguez and published by John Wiley & Sons. This book was released on 2018-02-21 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book C C Bond Activation written by Guangbin Dong and published by Springer. This book was released on 2014-09-18 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book Copper and Palladium Catalyzed Benz fused Heterocycle Synthesis Via Intramolecular Cross Coupling and C H Bond Functionalization Strategies written by Laurie Lynn Joyce and published by . This book was released on 2009 with total page 906 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is a summary of research conducted in the laboratory of Professor Robert A. Batey at the University of Toronto. The manuscript is divided into three chapters.Chapter one gives a general overview of methods for metal-catalyzed synthesis of heterocycles through carbon-heteroatom (C--Y) bond-forming events.Chapter two describes the intramolecular copper-catalyzed synthesis of 2aminobenzoxazoles through the coupling of aryl bromides with ureas. Reaction conditions were optimized through studies examining the effect of changing various reaction parameters including temperature, catalyst and ligand loadings, solvent choice, and degree of dryness of the reaction system. Optimized reaction conditions involve heating o-bromophenylurea precursors with 10 mol% copper iodide and 20 mol% 1,10-phenanthroline ligand in the presence of the weak base CS2CO3 (1.2 equiv) in a 1:1 acetonitrile:xylenes solvent system at 110-120°C to give 2-aminobenzoxazole products in good to excellent conversions and yields for a reaction time of 24 hours, These reactions were found to require strictly anhydrous reaction conditions and are effective only for N,N',N'-trisubstituted o-bromophenylureas.Chapter three describes a novel paliadium(0) catalyzed intramolecular oxidative C--H bond functionalization/C--S bond formation reaction for the synthesis of 2aminobenzothiazoles and related heterocycles. Reaction optimization studies were conducted by examining the effect of changing various reaction parameters while monitoring the progress of the reactions using HPLC. Optimized reaction conditions involve heating arylthiourea substrates with 3 mol% palladium tetrakistriphenylphosphine with activated 10 mol% manganese dioxide in acetonitrile solvent under an oxygen atmosphere at 80°C to give cyclized 2-aminobenzothiazole products in excellent yields. Anhydrous reaction conditions are required, and only N,N',N'-trisubstituted phenylthioureas were found to be suitable precursors to 2aminobenzothiazoles. This methodology offers improved efficiency and atom economy over previous metal-catalyzed methods that require ortho-halo arylthiourea precursors, thereby significantly improving the availability of phenylthiourea starting materials. Unlike for other palladium-catalyzed C--H functionalization reactions typically utilizing Pd(II) and a co-oxidant such as Cu(OAc)2 under oxidative conditions, we propose that the main role of activated MnO 2 is to act as a porous surface/sink to adsorb oxygen and deliver it to paliadium(0) to form a peroxo-paliadium(II) species.
