Download or read book Synthesis of Novel Cyclopentadienyl Cobalt I complexes and Their Application in 2 2 2 Cycloaddition Reactions written by Indre Thiel and published by . This book was released on 2013 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of Cationic Cobalt I complexes for Enantioselective Cycloaddition and Hydrofunctionalization Reactions written by Mahesh M. Parsutkar and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Developments of new catalytic transformations by using earth-abundant metal (base-metal) catalysts have played a significant role in modern civilization and will continue to play a vital role towards maintaining and improving our quality of life. Particularly, these transformations have had a tremendous impacts on the agricultural, transport, energy, and pharmaceutical sectors. This field of base-metal catalysis would enjoy added benefits with the utilization of sustainable feedstock carbon sources for fine chemical synthesis. However, the dual problems of activation of thermodynamically stable precursors (ethylene, CO2, H2, CO, aldehydes, acrylates, HCN) and their highly stereoselective incorporation into other readily available substrates (1,3-dienes, alkynes, enynes) pose new challenges. In a nutshell, the development of benign catalysts for employing sustainable feedstock starting materials has the potential to transform inexpensive materials into valuable precursors for fine chemical synthesis. My dissertation work focuses on the development of scalable, atom-economical, and cost-effective catalytic methods for the preparation of value-added products relevant to fine chemicals. The overarching aims are to use sustainable feedstocks or readily available precursors, and environmentally benign chemistry. To achieve these goals, three efficient catalytic methods have been developed which employ complexes of an earth-abundant metal, cobalt, with ligands derived from naturally occurring amino acids or commercially available bis-phosphine ligands. The key to success was a systematic ligands investigation that inspired the design and synthesis of novel ligands to achieve high chemo-, regio-, and enantioselectivities. In the first methodology, a broadly applicable method affecting [2+2] cycloaddition between several alkynes and alkenyl derivatives to form cyclobutenes has been disclosed. A library of >70 nearly enantiopure cyclobutenes, which are ubiquitous motifs in bioactive compounds, have been synthesized in excellent yields. In the second methodology, ligand controlled regio-divergent enantioselective synthesis of primary and secondary homoallylic boronates (>50 examples) from readily available 1,3-dienes and a common boron reagent have been developed. Furthermore, the hydrofunctionalization of 1,3-dienes program has been extended to unprecedented enantioselective hydroacylation of 1,3-dienes. This method opens a realm to achieve the synthesis of enantiopure alpha- or beta-chiral center containing ketones. In all the mentioned transformations above, cationic Co(I)- species has been invoked as an active catalyst. To further corroborate the role of cationic Co(I)-complexes, a reliable protocol has been developed to synthesize, isolate discrete neutral and cationic Co(I)-complexes and characterized by X-ray crystallography. These isolated cationic complexes serve as an excellent single-component catalyst for heterodimerization, hydroboration, and hydroacylation, suggesting the key role of cationic Co(I)-complexes in these transformations. While developing these efficient methodologies, striking ligand, counterion, and solvent effects have been revealed along with a unique role of a cationic Co(I) intermediate in the reactions which advanced novel fundamental concepts. We believe that these cationic Co(I) complexes have broader utility in homogeneous catalysis. We hope that the rational evolution of a mechanism-based strategy that led to the eventual successful outcome and the attendant support studies will add to the burgeoning organometallic chemistry of cobalt and its applications with further implications beyond the synthetic reactions described in this dissertation.
Download or read book Cyclopentadienyl Cobalt Dicarbonyl Induced Cyclizations of Diyne enes in Synthesis of Cyclohexadiene Cobalt Complexes Applications Towards the Synthesis of Estrone written by Ethan Dane Sternberg and published by . This book was released on 1982 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Exploring the Chemistry of Cyclopentadienyl cobalt cyclobutadiene CpCoCb Complexes and Synthesis of Side chain CpCoCb Polymers written by Preeti Chadha and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthetic metallopolymers have acquired ample attention recently due to their potential applications as precursors to functional soft materials. Organometallic polymers combine the best of both organic and inorganic polymers. Polyferrocenes comprise the major portion of organometallic polymers. Therefore, quest for new monomeric precursors to organometallic polymers has expediated. One efficient method for obtaining main-chain metallopolymers is by the ring opening polymerization (ROP) of strained cyclic metallacylophanes(MCPs). Organometallic polymers containing cyclopentadienyl-cobalt-cyclobutadiene (CpCoCb) have been targeted since early 1990's due to their isoelectronic nature (cf. ferrocene) with three major groups working in this area. The early CpCoCb containing polymers were prepared by alkyne dimerization of a bis-alkyne at the Co(I) centre, which did not provide good control over the molecular weights of the polymers generated. In search of novel Co(I) monomers for ROP, synthesis of sila- and germa- [2]cobaltoarenophanes was undertaken via. unprecedented direct dilthiation of (CpCoCb*) (Cb* = tetramethylcyclobutadiene) and subsequent treatment with the main group dihalides. However, attempts to ring open the CH2-SiMe2 bridged [2]cobaltoarenophanes were unsuccessful, which was attributed to the lower degree of strain in these molecules. An alternative route to [1]cobaltoarenophanes was proposed taking advantage of alkyne dimerization at a substituted CpCo(I) complex featuring a coordinated pendent alkyne. In this regard, alkyne-appended cyclopentadienyl ligands were developed and their utility was explored in reaction with early and late transition metals such as Ti, Fe, Co and Ni. This resulted in the formation of bis-alkynyl metallocenes of Ti and Co and half sandwich Ni complexes featuring a pendent alkyne. Synthesis of side chain cobalt(I) polymers demonstrating the CpCoCb framework has also been explored, using pre-functionalized Cp ligands incorporating a polymerizable vinyl moiety.
Download or read book The Cobalt mediated 2 2 2 cycloaddition of Bis trimethylsilyl Acetylene to the 2 3 double Bond of Benzofurans written by Brian Allan Siesel and published by . This book was released on 1996 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cobalt Catalysis in Organic Synthesis written by Marko Hapke and published by John Wiley & Sons. This book was released on 2020-04-06 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a much-needed account of the formidable "cobalt rush" in organic synthesis and catalysis Over the past few decades, cobalt has turned into one of the most promising metals for use in catalytic reactions, with important applications in the efficient and selective synthesis of natural products, pharmaceuticals, and new materials. Cobalt Catalysis in Organic Synthesis: Methods and Reactions provides a unique overview of cobalt-catalysed and -mediated reactions applied in modern organic synthesis. It covers a broad range of homogeneous reactions, like cobalt-catalysed hydrogenation, hydrofunctionalization, cycloaddition reactions, C-H functionalization, as well as radical and biomimetic reactions. First comprehensive book on this rapidly evolving research area Covers a broad range of homogeneous reactions, such as C-H activation, cross-coupling, synthesis of heterocyclic compounds (Pauson-Khand), and more Chapters on low-valent cobalt complexes as catalysts in coupling reactions, and enantioselective cobalt-catalyzed transformations are also included Can be used as a supplementary reader in courses of advanced organic synthesis and organometallic chemistry Cobalt Catalysis in Organic Synthesis is an ideal book for graduates and researchers in academia and industry working in the field of synthetic organic chemistry, catalysis, organometallic chemistry, and natural product synthesis.
Download or read book Seven membered Carbocycle Synthesis by Cobalt mediated 3 2 2 Allyl alkyne Cycloaddition Reactions and Novel 5 2 Cyclopentadiene alkyne Ring Expansions written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Cobalt mediated Intermolecular 2 2 2 Cycloaddition of Diynes with Alkenes written by Barry Mark Johnson and published by . This book was released on 1990 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organometallics in Organic Synthesis written by Armin de Meijere and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: More and more possible applications of organometallic compounds in organic synthesis have been uncovered and a growing number of scientists are attracted to this area of research. This book presents an state-of-the-art account of the successful application of main- and transition metal mediated syntheses. It will stimulate new ideas and initiate further research in all areas of this fascinating chemistry.
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.
Download or read book Development of Novel Cyclopentadienone Based Transition Metal Complexes for Catalytic and Electrocatalytic Transfer Hydrogenation of Polar Bonds written by Weiwei Wu and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis and Rearrangements of Cyclopentadienylcobalt Diene Complexes written by Joseph Anthony King and published by . This book was released on 1983 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Organocatalytic Cycloadditions for Synthesis of Carbo and Heterocycles written by Prof. Min Shi and published by John Wiley & Sons. This book was released on 2018-07-16 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive resource to the development and recent progress of zwitterion-oriented cycloadditions promoted by organoamines, organophosphines, N-heterocyclic carbenes Organocatalytic Cycloadditions for Synthesis of Carbo- and Heterocycles offers a clear explanationto thedevelopment of and the information on the latest research pertaining to zwitterion-oriented cycloadditions promoted by organoamines, organophosphines, N-heterocyclic carbenes. The authors—noted experts in the field—include a comprehensive review to the investigations of the reaction mechanisms and explore the synthesis of different products from the same starting materials. Filled with illustrative examples and designed to be accessible, the text shows how to control the chemo-, regio- and stereoselectivity and explains the further design of novel cycloaddition reactions catalyzed by organoamines and organophosphines based on zwitterion-oriented synthetic strategy. This important text: Explains why the formation of carbo- and heterocycles is a key transformation in organic synthesis. Offers a clear description to the development of zwitterion-oriented cycloadditions promoted by organoamines, organophosphines, N-heterocyclic carbenes, and explores the latest research Contains the most current examples involving synthetic transformations of organocatalytic cycloadducts Includes contributions from noted experts in the field of organic synthesis Written for organic chemists, pharmaceutical chemists, chemists in industry, graduates, and librarians, Organocatalytic Cycloadditions for Synthesis of Carbo- and Heterocyclesis is the essential guide to the topic.
Download or read book Synthesis and Characterization of Bis cyclopentadienyl Uranium IV Complexes written by Anita L. Arduini and published by . This book was released on 1978 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reagent, Cp2U(NEt2)2, was formed from a reaction of U(NEt2)4 with cyclopentadiene. The reactive nature of the uranium-nitrogen bonds in the starting tetrakisamide complex was retained by Cp2U(NEt2)2. This compound underwent both acid displacement and insertion type reactions to yield a variety of pseudo-six-coordinate complexes of the formula, Cp2U(chelate)2 where chelate = 02CNEt2, OSCNEt2 r S2CNEt2, C>2CPh, C>2CMe, 02CCMe3, OSCPh, OSCMe, cis-(OCMe)(OCCHMe2)Re(CO)4, cis-(OCMe)2Re(CO)4. The compounds, Cp2U(OSCNEt2)2, Cp2U(S2CNEt2)2, and Cp2U(OSCPh)2 were monomeric, Cp2U(02CCMe3)2, dimeric and Cp2U(02CNEt2)2, polymeric in solution, as determined from molecular weight measurements. The spectroscopic data of the compounds are consistent with the designated chelate coordination of the ligands and a pentahapto bonding mode for the cyclopentadienyl rings. The complexes are considered to have octahedral geometry with the ligands and Cp rings in mutually cis positions. The variable temperature NMR data of Cp2U(OSCNEt2)2, Cp2U(S2CNEt2)2, Cp2U(OSCPh)2, and Cp2U[cis-(OCMe)2Re- (CO)4]2 indicated that metal-centered rearrangement processes were averaging non-equivalent environments of the chelate ligands. The carbamates were also assumed to have restricted rotation about the carbon-nitrogen bonds. The AG^ value for the rearrangement in Cp2U[cis-(OCMe)2Re(CO)4]2 was calculated to be 13.5 ± .5 kcal/mole in toluene and 13.7 ± .4 kcal/mole in CH2C12 at a coalescence temperature of 35°C. The rearrangements in the other complexes were still proceeding rapidly even at the lowest accessible temperatures. The dimeric structure of Cp2U(C^CCMe^)2 was assumed to contain four symmetrically bridging carboxylate ligands as the NMR data only showed one methyl resonance. The reagent, Cp2U(NEt2)2, underwent aminolysis reactions with HNPh2, HNC^H^, HNC^H2Me2 and HNC^Me^(COOEt). The compounds, Cp2U(NEt2)(NPh2) and Cp2U[NC^Me^(COOEt)]2 were isolated in a pure form whereas the other pyrroles gave mixtures of mono- and bis-substituted complexes. Attempts to make dichloro containing compounds of the type C1.2U(NR2)2 from UCl^ and the lithio or potassio salts of amines were not completely successful. Although pure Cl~U[N (C ,H, ..)_]_ was obtained, the other complexes, £ b 11 z ^ C12U[N(SiMe^)2]2 and Cl2U(NEt2)2' were contaminated with the trisamide compounds, C1U(NR2)2* Subsequent reactions with cyclopentadiene did not produce pure Cp2UCl2 but mixtures of Cp2UCl2 and Cp^UCl.
Download or read book Advanced Strategies for Catalyst Design written by Laura Orian and published by MDPI. This book was released on 2021-04-21 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The invention of novel and improved catalysts has a valuable impact on human activities and on our planet. Efficient catalysts are expected to be stable, active, and selective. In the past, the development of new catalysts has mainly depended on trial and error, a laborious and time-consuming approach. Nowadays, the mechanistic details of numerous important chemical reactions have been unraveled, and this information is useful for intelligently design novel catalysts. Thus, all the efforts devoted to facilitating a deep understanding of intricate catalytic mechanisms and to the preparation of novel catalysts relying on this are priceless. Chemists must set up adequate strategies, merging experimental and computational knowledge and abilities toward tuning the performance of molecules that might be successful in the lab. The contributions in this book collection are some examples of this modern chemical design.
Download or read book Journal of the Indian Chemical Society written by Indian Chemical Society and published by . This book was released on 2007 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bibliography of Mass Spectroscopy Literature for 1971 written by and published by . This book was released on 1973 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt:
