EBookClubs

Read Books & Download eBooks Full Online

EBookClubs

Read Books & Download eBooks Full Online

Book Development of New Transition Metal Catalysts for C N Bond Formation and Continuous Flow Processes for C F Bond Formation

Download or read book Development of New Transition Metal Catalysts for C N Bond Formation and Continuous Flow Processes for C F Bond Formation written by Nathaniel Hamilton Park and published by . This book was released on 2015 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this dissertation addresses the development of new methodologies and processes to form carbon-nitrogen (C-N) and carbon-fluorine (C-F) bonds. The development of methods for the formation of C-N and C-F bonds are highly important to chemistry in general and find broad application in many different areas of research. With regard to C-N bond formation, the development of new nickel and palladium catalyst for C-N cross-coupling is presented. Finally, the development of a new process to enable the rapid preparation of aryl fluorides via the Balz-Schiemann reaction is explored. Chapter 1. Development of an Air-Stable Nickel Precatalyst for the Amination of Aryl Chlorides, Sulfamates, Mesylates, and Triflates. A new air-stable nickel precatalyst for C-N cross-coupling is reported. The developed catalyst system displays a greatly improved substrate scope for C-N bond formation to include both a wide range of aryl and heteroaryl electrophiles and aryl, heteroaryl, and alkyl amines. The catalyst system is also compatible with weak base, allowing for the amination of substrates containing base-sensitive functional groups. Chapter 2. Design of New Ligands for the Palladium-Catalyzed Arylation of a- Branched Secondary Amines. In Pd-catalyzed C-N cross-coupling reactions, a-branched secondary amines are difficult coupling partners and often produce low yields of the desired product. To provide a robust method for accessing N-aryl a-branched tertiary amines, new catalysts have been designed to suppress undesired side reactions often encountered when these amine nucleophiles are used. These advances enabled the arylation of a wide array of sterically encumbered amines, highlighting the importance of rational ligand design in facilitating challenging Pd-catalyzed cross-coupling reactions. Chapter 3. Rapid Synthesis of Aryl Fluorides in Continuous Flow via the Balz- Schiemann Reaction. The synthesis of aryl fluorides (ArF) is of critical importance for the development of new and potent pharmaceuticals and agrochemicals. While there have been numerous and intense research efforts focused on developing new fluorination methods, the Balz-Schiemann reaction remains a valuable and efficient means of aryl C-F bond construction from a vast pool of available aryl amines. However, the harsh reaction conditions, modest yields, and often prohibitive safety concerns have limited the general application of this methodology. Here, we have developed a semi-flow process that enables safe handling of the potentially explosive aryl diazonium salt intermediates as well as improved yields of the desired aryl fluoride products. This process has been demonstrated on an array of different aryl and heteroaryl amine substrates containing a variety of different functional groups.

Book Design and Synthesis of New Ligand Systems for Transition Metal Catalysed Carbon carbon Cross coupling  Hydrogenation and Hydrosilation

Download or read book Design and Synthesis of New Ligand Systems for Transition Metal Catalysed Carbon carbon Cross coupling Hydrogenation and Hydrosilation written by Daniel Carleton and published by . This book was released on 2013 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: An ever increasing global requirement for consumables consequently increases the demand for often non-renewable resources, resulting in the need for greater efficiencies in synthetic processes. In order to achieve this goal, the field of organometallic catalysis has been ever growing to support the ideals of cleaner and greener chemistry. In this thesis studies concerning a series of new bidentate donor ligands employing both the NHC and PYA donor groups for use in transition metal catalysis is presented. The successful synthesis of the bidentate ligand N,N'-dimethyl-N''-pyridin-4-yl nicotinamide with both a remote NHC and PYA donor groups is reported, along with the synthesis of the precursor materials 1-methyl-3-(2-oxo-2-(pyridin-2-ylamino)ethyl)-1H-imidazol-3-ium and 1-methyl-3-(2-oxo-2-(pyridin-4-ylamino)ethyl)-1H-imidazol-3-ium for the formation of other bidentate ligands incorporating the imidazolium NHC and PYA donor groups. The iridium complex IrH(L-R4)(CO)(PPh3)2 containing the new ligand L-R4 was prepared through reaction of N,N'-dimethyl-N''-pyridin-4-yl nicotinamide with Vaskas Complex. Chapter one explains the ideology behind green chemistry and our constant drive to maintain a clean and green planet. Chapter two describes the effect of donor groups on a metal centre with focus on the NHC and PYA donor groups and their advantages over previous work in this area. Chapter three describes the development of synthetic routes to the new target ligands and chapter four explains the studies involving the metal precursor substrates and ligand coordination. Chapter five contains details of the relevant experimental data. The work described in this thesis will provide an excellent starting point for those wishing to further explore the synthesis and study of bidentate NHC and PYA donor ligands in catalysis by transition metals.

Book TRANSITION METAL CATALYZED CARBON CARBON AND CARBON NITROGEN BOND FORMATION AND ASYMMETRIC CATALYSIS WITH BISOXAZOLIDINE LIGANDS

Download or read book TRANSITION METAL CATALYZED CARBON CARBON AND CARBON NITROGEN BOND FORMATION AND ASYMMETRIC CATALYSIS WITH BISOXAZOLIDINE LIGANDS written by Hanhui Xu and published by . This book was released on 2012 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: Palladium-phosphinous acids and chlorophosphine analogues have attracted increasing interest due to their high catalytic activity in various organic transformations, long shelf-life and facile handling. In this thesis, it is reported that these catalysts are very useful in Negishi cross-couplings of aryl or acyl halides with aliphatic and aromatic organozinc reagents. Similarly, palladium-phosphinous acids were employed in the formation of sterically hindered biaryls exhibiting at least two ortho substituents from aryl halides and aryl Grignard reagents.

Book N Heterocyclic Carbenes in Transition Metal Catalysis and Organocatalysis

Download or read book N Heterocyclic Carbenes in Transition Metal Catalysis and Organocatalysis written by Catherine S.J. Cazin and published by Springer. This book was released on 2010-11-04 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: N-Heterocyclic Carbenes in Transition Metal Catalysis and Organocatalysis features all catalytic reactions enabled by N-heterocyclic carbenes (NHCs), either directly as organocatalysts or as ligands for transition metal catalysts. An explosion in the use of NHCs has been reported in the literature during the past seven years making this comprehensive overview highly apropos. The book begins with an introductory overview of NHCs which could have been subtitled all you need to know about NHCs. The main body of the book is dedicated to applications of NHCs in catalysis. In addition to the success stories of NHCs in metathesis, NHCs in cross coupling and more recently NHCs in organocatalysis, all other less publicized areas are also covered. As the success of NHCs is generally attributed to their potential to stabilize metal centres, the inclusion of a chapter on the decomposition of NHC catalysts is pertinent. The book closes with a chapter describing the applications of NHCs in industrial processes, which is the first coverage of its kind, and brings a unique industrial context to this book. Included in this book: Historical aspects of NHCs Synthetic pathways to NHC precursors, free NHCs and complexes Methods of characterisation of NHCs and related complexes Electronic properties of NHCs Steric properties of NHCs and models for their description NHCs for metathesis and cross-coupling reactions NHCs as organocatalysts NHC Transition-Metal mediated oxidations, additions to multiple bonds, polymerisation and oligomerisation, cyclisations, direct arylations, reactions involving CO, C-F and C-H bond activation, ... Decomposition of NHC-containing catalysts Industrial applications involving NHC-containing catalysts N-Heterocyclic Carbenes in Transition Metal Catalysis and Organocatalysis provides a fresh view of NHCs since most contributors are young emerging researchers in the field of homogeneous catalysis using NHCs. This group of contributors is complemented by highly established academic researchers and an industrialist. This book is comprehensive, from the basic features of NHCs to the latest advances, hence it is suitable for both the novice and the expert.

Book Transition Metal Catalyzed C N Bond Formation Via Addition of Nitrogen Nucleophiles Towards Alkenes and Related Tandem Cyclization Reactions

Download or read book Transition Metal Catalyzed C N Bond Formation Via Addition of Nitrogen Nucleophiles Towards Alkenes and Related Tandem Cyclization Reactions written by Dong Xing and published by Open Dissertation Press. This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Transition Metal-catalyzed C-N Bond Formation via Addition of Nitrogen Nucleophiles Towards Alkenes and Related Tandem Cyclization Reactions" by Dong, Xing, 邢栋, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b4658915 Subjects: Ring formation (Chemistry) Transition metal catalysts Polycyclic compounds - Synthesis

Book Ruthenium N Heterocyclic Carbene and Ruthenium Acetylide Complexes Supported by Macrocyclic Porphyrin Or Tetradentate Schiff Base Ligands

Download or read book Ruthenium N Heterocyclic Carbene and Ruthenium Acetylide Complexes Supported by Macrocyclic Porphyrin Or Tetradentate Schiff Base Ligands written by Ka-Ho Chan and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Ruthenium-N-heterocyclic Carbene and Ruthenium Acetylide Complexes Supported by Macrocyclic Porphyrin or Tetradentate Schiff Base Ligands: Synthesis, Structure and Catalytic Applications" by Ka-ho, Chan, 陳嘉豪, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled RUTHENIUM-N-HETEROCYCLIC CARBENE AND RUTHENIUM ACETYLIDE COMPLEXES SUPPORTED BY MACROCYCLIC PORPHYRIN OR TETRADENTATE SCHIFF BASE LIGANDS: SYNTHESIS, STRUCTURE AND CATALYTIC APPLICATIONS Submitted by Chan Ka Ho for the degree of Doctor of Philosophy at The University of Hong Kong in March 2015 Transition metal-catalyzed C-C and C-N bond formation reactions are important transformations in synthetic organic chemistry. In the endeavor of this thesis to develop robust/versatile catalysts for these reactions, the trans effect imposed by N-heterocyclic carbene (NHC) and acetylide ligand onto ruthenium complexes supported by macrocyclic porphyrin or tetradentate Schiff-base ligands was studied. The catalytic activity of these novel ruthenium complexes towards carbene and/or nitrene transfer and insertion reactions was also explored. II A series of bis(NHC)ruthenium(II) porphyrin complexes [Ru (Por)(NHC) ] were synthesized by deprotonation of imidazolium salt using a strong base. These complexes displayed unprecedentedly high catalytic activity towards carbene/nitrene transfer and insertion reactions, including alkene cyclopropanation and aziridination, carbene C-H, S-H, N-H and O-H insertions, and nitrene C-H insertion with product -1 turnover frequency up to 1950 min . Carbene modification of N-terminus of peptide o II at 37 C was achieved. Chiral [Ru (D -Por)(NHC) ] catalyst led to highly 4 2 enantioselective carbene/nitrene transfer and insertion reactions with up to 98% ee. DFT calculations revealed that the strong σ-donor strength of trans axial NHC ligand stabilizes the formation of metal-carbene and metal-nitrene intermediate from decomposition of diazo compounds and organic azides, which is crucial for the transition metal-catalyzed oxidative C-C and C-N bond formation reactions to proceed under mild reaction conditions. II A series of ruthenium Schiff-base complexes cis-β-[Ru (Schiff-base)(CO) ] were synthesized and characterized. These complexes showed high catalytic activity towards enantioselective cyclopropanation, carbene C-H and Si-H bond insertions. II t The cis-[Ru (2-CPh -4- Bu-Schiff-base)(CO) ]-catalyzed intermolecular 3 2 cyclopropanation of styrene with EDA in CH Cl afforded desired cyclopropane 2 2 product in 90% isolated yield and 95% ee with a product turnover number of 9000. Excellent trans- and high enantioselectivity were observed with wide substrate scope, including conjugated, electron-rich, electron-deficient and aliphatic terminal alkenes. Carbene C-H and Si-H insertion reactions proceeded smoothly with II t cis-[Ru (2-CPh -4- Bu-Schiff-base)(CO) ] as catalyst, giving the desired products in 3 2 82-97% yields with excellent enantioselectivity (up to 99% ee). The same complex was also catalytically active towards intramolecular cyclopropanation and intramolecular alkyl carbene sp C-H bond insertion to give cis-products with up to 99:1 cis: trans ratio and with excellent enantioselectivities (up to 98% ee). DFT calculations on the intermolecular cyclopropanation catalyzed by II cis-β-[Ru (Schiff-base)(CO) ] revealed that among the ruthenium-carbene intermediates possibly involved in the reactions, the cis-β species are more stable than their trans isomer with

Book The Search for Catalysts Using the Cooperativity of Transition Metals and Heterocyclic Ligands

Download or read book The Search for Catalysts Using the Cooperativity of Transition Metals and Heterocyclic Ligands written by Sang Van and published by . This book was released on 2002 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of new and efficient catalysts plays an important role in chemical research. The inspiration for finding new catalysts includes long-term benefits such as (a) efficient, atom-economical reactions; (b) chemoselective reactions under mild conditions, obviating the need for protection and deprotection of functional groups; and (c) reduction of chemical waste in the production of fine chemicals for pharmaceuticals. For these purposes, artificial enzyme mimics are exploited. In the preparation of such catalysts, a promising approach is to translate the principles of enzyme catalysis for the design of new catalytic materials. In this research, we used design features of the cooperativity of Lewis acid transition metals and heterocyclic ligands designed to provide hydrogen bond donor (A) and acceptor (B), inspired by Nature's enzymes, to catalyze reactions of polar molecules such as water, alcohols, or amines with organic molecules.* To synthesize our catalysts, we envisioned anchoring a transition metal to a heterocycle which features a reasonably acidic N-H group (A). In this research, we prepared 10 pyrazole ligands and 35 of their complexes, 15 of which were analyzed by X-ray diffraction. Furthermore, isoelectronic and isosteric complexes incapable of donating or accepting hydrogen bond(s) were also synthesized to determine the relationship between hydrogen-bond donating properties and catalytic efficiency. All the complexes were characterized by NMR spectroscopy, IR spectroscopy, and elemental analysis. Part of our studies to date have focused on the hydrolysis of unactivated amide bonds, thought to be a more difficult challenge than similar reactions of phosphate diesters. We also focused on the use of hydrogen-donating-group-assisted in catalysis of chemoselective hydrogenation of imines. We also used bifunctional catalysts to catalyze regio- and stereoselective dimerization of terminal alkynes, and hydrogen transfer hydrogenation of aldehydes, ketones, and imines. The catalysts can also catalyze cyclization and coupling reactions of alkynols. Significantly, these catalytic processes involve both C-C and C-O bond formation with diastereo- and regioselectivity. These results are fruitful because we have opened another field of catalysis using the combined effects of hydrogen-bond donating ligands and Lewis acidic transition metals. *Please refer to dissertation for diagrams.

Book Palladium catalyzed Carbon carbon  Carbon nitrogen and Carbon oxygen Bond Formation

Download or read book Palladium catalyzed Carbon carbon Carbon nitrogen and Carbon oxygen Bond Formation written by Xiaohua Huang and published by . This book was released on 2003 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: New methods for Pd-catalyzed cross-coupling reactions of aryl halides or arenesulfonates are described. Key to the success of these transformations is the proper choice of ligand and reaction conditions. Palladium catalysts supported by bulky, monodentate phosphine ligands with a biaryl backbone or the bidentate ligand, Xantphos, effectively promote the formation of ca-aryl carbonyl compounds. Base-sensitive functional groups are better tolerated when a weak base, such as K3PO4, is used. One of the most difficult transformations in Pd catalysis, the intermolecular C-O bond formation between primary alcohols and electron-neutral or even electron-rich aryl halides, was effectively promoted by the use of a new generation of ligands, 3-methyl-2-di-t-butylphosphinobiaryl. The one-step synthesis of ligands from cheap starting materials, as well as the mild reaction conditions employed for the coupling reactions, enables the practical use of Pd catalysis to access aryl alkyl ethers for the first time. Continuing study of Pd-catalyzed C-N bond-forming processes using biaryl monophosphine ligands led to the discovery of a structural derivative of these ligands, 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl. This ligand, in combination with a Pd source, produces a catalyst system with both a greater degree of activity and of stability than those that use our previous ligands. Substrates that were not amenable to Pd catalysis previously are reexamined using this new catalyst system, and excellent results are obtained.

Book Olefin Polymerization

Download or read book Olefin Polymerization written by Walter Kaminsky and published by Wiley-VCH. This book was released on 2006-08-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With an enormous velocity, olefin polymerization has expanded to one of the most significant fields in polymers since the first industrial use about 50 years ago. In 2005, 100 million tons of polyolefins were produced - the biggest part was catalyzed by metallorganic compounds. The Hamburg Macromolecular Symposium 2005 with the title "Olefin Polymerization" involved topics such as new catalysts and cocatalysts, kinetics, mechanism and polymer reaction engineering, synthesis of special polymers, and characterization of polyolefins. The conference combined scientists from different disciplines to discuss latest research results of polymers and to offer each other the possibility of cooperation. This is reflected in this volume, which contains invited lectures and selected posters presented at the symposium.

Book Advances in Late Metal Carbon Nitrogen Bond Formation for the Synthesis of Substituted Heterocycles

Download or read book Advances in Late Metal Carbon Nitrogen Bond Formation for the Synthesis of Substituted Heterocycles written by Nicolas Rotta-Loria and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Late-metal catalyzed cross-couplings have emerged as efficient and selective methodologies for the formation of C-C and C-N bonds. The ability to synthesize complex heterocycles from cheap and abundant starting materials is an invaluable asset to the pharmaceutical industry, given that many pharmaceuticals contain at least one heterocyclic component. This reactivity can be achieved by tuning the steric and electronic properties of ancillary ligands to support metal catalysts in the reaction steps leading to the target substrate. The Stradiotto group has developed several state-of-the-art methodologies involving ligands for palladium catalysis, for both C-C and C-N bond-forming reactions. These methodologies can be amalgamated into a multicomponent reaction platform to synthesize more complex products from simple materials. Chapter 1 outlines this concept with the application of a Mor-DalPhos/Pd catalyst in the one-pot synthesis of indoles from acetone and simple amines involving C-C and C-N bond formation. The robust nature of this method can be extended to include benchtop reaction conditions in a one-step, one-pot synthesis of indoles, thus representing a useful synthetic protocol. While palladium provides a powerful tool for C-C and C-N bond formation, the general trend in catalysis has shifted away from the precious metals toward first row metals as economic alternatives. Nickel complexes have recently emerged as excellent catalysts for a number of amination reactions. The ability to utilize ammonia also represents a sought after reaction, due to the widespread availability and synthetic utility of amino-functionalized products. In this regard, Chapter 2 will focus on the development and application of both commercially available and strategically designed ligand classes for the monoarylation of ammonia with substituted heterocycles. Hydrazine represents an important synthon in synthetic chemistry. It is synthesized on multi-ton scale every year and represents an important building block in many industrial processes. Many synthetic challenges arise from using free hydrazine as reactant, which has led to lethargic growth of its application in the field of late-metal catalyzed C-N bond-formation. However, gold-catalyzed methodologies have been developed utilizing NHC ligands to allow for the hydrohydrazination of alkynes with parent hydrazine. Chapter 4 examines the development and application of a series of (PR3)AuCl complexes for use in such transformations, leading to the identification of the first effective phosphine-bound gold complex for use in the hydrohydrazination of alkynes at room temperature.

Book N Heterocyclic Carbenes in Transition Metal Catalysis

Download or read book N Heterocyclic Carbenes in Transition Metal Catalysis written by Frank Glorius and published by Springer. This book was released on 2010-11-19 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book leading experts have surveyed major areas of application of NHC metal complexes in catalysis. The authors have placed a special focus on nickel- and palladium-catalyzed reactions, on applications in metathesis reactions, on oxidation reactions and on the use of chiral NHC-based catalysts. This compilation is rounded out by an introductory chapter and a chapter dealing with synthetic routes to NHC metal complexes.

Book Application of Transition Metal Catalysts in Organic Synthesis

Download or read book Application of Transition Metal Catalysts in Organic Synthesis written by L. Brandsma and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous catalysis is an important strategy for the synthesis of high-valued chemicals. L. Brandsma has carefully selected and checked the experimental procedures illustrating the catalytic use of copper, nickel, and palladium compounds in organic synthesis. All procedures are on a preparative scale, make economic use of solvents and catalysts, avoid toxic substances and have high yields.

Book Defined Transition Metal Complexes for Catalytic Oxidative C N Bond Formation

Download or read book Defined Transition Metal Complexes for Catalytic Oxidative C N Bond Formation written by Alvaro Iglesias and published by . This book was released on 2009 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with the development of transition metal based processes for C-N bond formation. To this end, it describes three different areas of research, the activation of azo-compounds for a concomitant aryl-amination under Pd(0)/Pd(II) catalysis, secondly, the use of gold catalysts for an oxidative diamination of alkenes led to the development of Au(I)/Au(III) catalysis. The latter process gave rise to stoichiometric experiments on the feasibility of oxidation of gold(I) complexes. This work was equally extended to investigate pathways of reductive C-N bond formation from Pd(II)-amidato complexes under oxidative conditions.

Book Transition Metal Dinitrogen Complexes

Download or read book Transition Metal Dinitrogen Complexes written by Yoshiaki Nishibayashi and published by John Wiley & Sons. This book was released on 2019-05-06 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive book that explores nitrogen fixation by using transition metal-dinitrogen complexes Nitrogen fixation is one of the most prominent fields of research in chemistry. This book puts the focus on the development of catalytic ammonia formation from nitrogen gas under ambient reaction conditions that has been recently repowered by some research groups. With contributions from noted experts in the field, Transition Metal-Dinitrogen Complexes offers an important guide and comprehensive resource to the most recent research and developments on the topic of nitrogen fixation by using transition metal-dinitrogen. The book is filled with the information needed to understand the synthesis of transition metal-dinitrogen complexes and their reactivity. This important book: -Offers a resource for understanding nitrogen fixation chemistry that is essential for explosives, pharmaceuticals, dyes, and all forms of life -Includes the information needed for anyone interested in the field of nitrogen fixation by using transition metal-dinitrogen complexes -Contains state-of-the-art research on synthesis of transition metal-dinitrogen complexes and their reactivity in nitrogen fixation -Incorporates contributions from well-known specialists and experts with an editor who is an innovator in the field of dinitrogen chemistry Written for chemists and scientists with an interest in nitrogen fixation, Transition Metal-Dinitrogen Complexes is a must-have resource to the burgeoning field of nitrogen fixation by using transition metal-dinitrogen complexes.

Book Cross coupling Reactions

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"--

Book C N Bond Formation Employing Palladium and Nickel Precatalysts Containing Anionic Phosphinobenzimidazole Ligands

Download or read book C N Bond Formation Employing Palladium and Nickel Precatalysts Containing Anionic Phosphinobenzimidazole Ligands written by Joseph P. Tassone and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this investigation, the catalytic utility of anionic, phosphinobenzimidzoles [Li(THF)2][1a] and [Li(THF)4][1b] in effecting the Buchwald-Hartwig amination reaction was examined. Specifically, the coordination chemistry of ligands [Li(THF)2][1a] and [Li(THF)4][1b] with palladium was studied in an attempt to synthesize a distinct precatalyst containing either 1a or 1b that could be screened for catalytic activity in the reaction of interest. Additionally, the screening of a Pd/[Li(THF)4][1b] catalyst system for activity in the Buchwald-Hartwig amination reaction was conducted concurrently. Complex 6, containing 1a, and complexes 7-12, containing 1b, were successfully synthesized, and characterized using multi-nuclear NMR spectroscopy. An optimized [Pd(cinnamyl)Cl]2/[Li(THF)4][1b] catalyst system was also developed, and performed the coupling of activated and deactivated aryl bromides with a selection of amines in moderate to excellent yields (36-97%). A preference for primary vs. secondary amine coupling partners, as well as a high selectivity for the monoarylated product, was observed during the course of these studies. To highlight the remarkable potential of anionic ligands in catalysis, the catalytic efficiency of the [Pd(cinnamyl)Cl]2/[Li(THF)4][1b] catalyst system was compared with a corresponding system utilizing the related, neutral phosphinobenzimidazole 2, with the anionic system displaying superior catalytic activity in the Buchwald-Hartwig amination reaction in almost all cases. This phenomenon was attributed to the more electron-rich catalytic intermediates present in the anionic system, enabling more rapid oxidative addition, and thus more efficient catalysis. Further screening of the anionic precatalyst [PPh4][PdCl2(k2-1b)] (10) and neutral precatalyst [PdCl2(k2-2)] (13) corroborated these results. Finally, preliminary studies examining the potential of 1b as an ancillary ligand in Ni-catalyzed C-N bond formation was undertaken. The coordination chemistry of 1b with nickel was explored, resulting in the formation of complex 14, whose tentative structure was assigned on the basis of NMR spectroscopic evidence. Furthermore, initial screening of a NiCl2(DME)/[Li(THF)4][1b] catalyst system in the cross-coupling of chlorobenzene and aniline did not result in observable product formation under various reaction conditions.