Author: Fred J. FleitzPublisher:
ISBN:
Category :
Languages : en
Pages : 618
Book Description
Studies on the Scope of the Palladium Catalyzed Reductive Diyne Cyclization
Author: Fred J. FleitzPalladium and Nickel Catalyzed Transformations Forming Functionalized Heterocycles
Author: Hyung YoonPublisher: Springer Nature
ISBN: 3030540774
Category : Science
Languages : en
Pages : 236
Book Description
This book presents Pd- and Ni-catalyzed transformations generating functionalized heterocycles. Transition metal catalysis is at the forefront of synthetic organic chemistry since it offers new and powerful methods to forge carbon–carbon bonds in high atom- and step-economy. In Chapter 1, the author describes a Pd- and Ni-catalyzed cycloisomerization of aryl iodides to alkyl iodides, known as carboiodination. In the context of the Pd-catalyzed variant, the chapter explores the production of enantioenriched carboxamides through diastereoselective Pd-catalyzed carboiodination. It then discusses Ni-catalyzed reactions to generate oxindoles and an enantioselective variant employing a dual ligand system. Chapter 2 introduces readers to a Pd-catalyzed diastereoselective anion-capture cascade. It also examines diastereoselective Pd-catalyzed aryl cyanation to synthesize alkyl nitriles, a method that generates high yields of borylated chromans as a single diastereomer, and highlights its synthetic utility. Lastly, Chapter 3 presents a Pd-catalyzed domino process harnessing carbopalladation, C–H activation and π-system insertion (benzynes and alkynes) to generate spirocycles. It also describes the mechanistic studies performed on these reactions.
Palladium Assisted Synthesis of Heterocycles
Author: Navjeet KaurPublisher: CRC Press
ISBN: 1351242598
Category : Medical
Languages : en
Pages : 482
Book Description
This book is a compilation of the recent applications of palladium catalysts in organic synthesis. The book demonstrates that it is a highly dynamic research field. This methodology has emerged as a powerful tool for the efficient and chemoselective synthesis of heterocyclic molecules. In the past few years, several strategies have been pointed out to pursue more efficient, sustainable, and environment friendly chemical processes. Among those strategies, catalysis and the design of new processes that avoid the use of toxic reagents have been the focus of intense research.
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 980
Book Description
Palladacycles
Author: Anant KapdiPublisher: Elsevier
ISBN: 0128165162
Category : Science
Languages : en
Pages : 420
Book Description
Palladacycles: Catalysis and Beyond provides an overview of recent research in palladacycles in catalysis for cross-coupling and similar reactions. In the quest for developing highly efficient and robust palladium-based catalysts for C-C bond formation via cross-coupling reactions, palladacycles have played a significant role. In recent years, they have found a wide variety of applications, ranging from catalysts for cross-coupling and related reactions, to their more recent application as anticancer agents. This book explores early examples of the use of palladacyclic complexes in catalysis employing azobenzene and hydrazobenzene as coordinating ligands. Its applications in processes such as selective reduction of alkenes, alkynes, or nitroalkanes are also covered. Palladacycles: Catalysis and Beyond reveals the tremendous advances that have taken place in the potential applications of palladacycles as versatile catalysts in academia and industry. It is a valuable resource for synthetic chemists, organometallic chemists, and chemical biologists. Reviews the importance and various applications of palladacycles in academic research and industry, including industrial scale applications Includes the impact of palladacycles on coupling reactions and potential applications as anticancer agents Features coverage of nano and colloidal catalysis via palladacyclic degradation
Palladium-catalyzed Carbonylative Synthesis of Acid Chorides and Use in Multicomponent Coupling Reactions
Author: Jeffrey QuesnelPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
"The palladium-catalyzed carbonylation of aryl halides has proven to be a powerful method for the synthesis of carbonyl-containing compounds. This thesis describes a unique way of performing palladium-catalyzed carbonylations: through the generation of acid chlorides as products and as reactive intermediates.Chapter 2 describes the application of palladium-catalyzed aryl iodide carbonylation to the five-component synthesis of imidazolinium carboxylates. This reaction involves the coupling of the palladium-catalyzed carbonylation of aryl halides with the cyclocarbonylation of [alpha]-chloroamides, and provides an efficient route to generate imidazolinium salts from aryl iodides, imines, and carbon monoxide. A variety of imidazolinium products can be synthesized, including those whose derivatives are relevant to pharmacologically active compounds. Subsequent deprotection and aromitization can then lead to triaryl-substituted imidazoles.In Chapter 3, we report a new approach to acid chloride synthesis via the palladium-catalyzed carbonylation of aryl iodides. The combination of sterically encumbered phosphines (PtBu3) and CO coordination has been found to facilitate the rapid carbonylation of aryl iodides into acid chlorides via reductive elimination from (tBu3P)(CO)Pd(COAr)Cl. The formation of acid chlorides can also be exploited to perform traditional aminocarbonylation reactions under exceptionally mild conditions (ambient temperature and pressure), and with a range of weakly nucleophilic substrates.Chapter 4 describes the adaptation of this acid chloride synthesis to include less reactive aryl bromide coupling partners. Interestingly, the same PtBu3 ligand found to be most efficient for acid chloride synthesis from aryl iodides also proved best for aryl bromide chlorocarbonylation, suggesting the unusual ability of this ligand to efficiently mediate both oxidative addition and reductive elimination reactions. Mechanistic studies show that the palladium coordination environment is an important aspect of the key C-Cl reductive elimination step. In contrast to smaller phosphine ligands, the bulky PtBu3 leads to the in situ formation of a three coordinate (tBu3P)(CO)Pd(COAr)Cl complexes, which can readily coordinate CO to facilitate reductive elimination. Trapping of in situ generated acid chlorides with simple hydrazine allows, for the first time, the efficient synthesis of unsubstituted aroyl hydrazides via a palladium-catalyzed carbonylation reaction.In Chapter 5, we describe density functional theory (DFT) study of the mechanism for the palladium/PtBu3 catalyzed chlorocarbonylation of aryl iodides into acid chlorides. The results demonstrate a synergistic effect of CO and phosphine ligands on oxidative addition and reductive elimination chemistry of aryl/aroyl halides, consistent with what has been noted in experiments. The reductive elimination of PhCOCl from the four-coordinate PhCOPd(PtBu3)Cl(CO) complex is found to proceed via a surprisingly low energy pathway, and is facilitated by the coordination of CO to the three-coordinate PhCOPd(PtBu3)Cl. Examination of a series of PhCOPd(PR3)Cl(CO) complexes (R = Me, Et, iPr, tBu) shows that while most phosphines generate relatively stable four-coordinate complexes, the tertiary steric bulk of PtBu3 destabilizes this complex by steric clashing with the cis-CO ligand. This significantly lowers the barrier to acid choride reductive elimination, and makes this step thermodynamically favourable.Chapter 6 presents an alternative to the catalytic acid chloride chemistry discussed in Chapters 3 and 4, where instead 4-dimethylaminopyridine (DMAP) is shown to couple with aryl halides and carbon monoxide to form isolable and highly electrophilic aroyl-DMAP salts. The reaction is easily scalable to prepare multigram quantities of product with low catalyst loadings, while the precipitation of these salts as they form leads to products with low impurities. " --
Homogeneous Palladium Catalyzed Cyclizations and Reductions
Author: Rebecca BraslauAnnual Commencement
Author: Stanford UniversityPalladium-catalyzed Silylstannylation-cyclization of 1,6-diynes ; Axial Chirality in (Z, Z)-1,3-dienes
Author: Sandra WarrenPublisher:
ISBN:
Category : Chirality
Languages : en
Pages : 886
Book Description
The silylstannane-mediated cyclization of mono-substituted 1,6-diynes is readily catalyzed by palladium in the presence of a weakly coordinating phosphine. The products of the reaction are highly functionalized carbo- or heterocycles. The reaction displays wide functional group compatibility, tolerating groups like carboxylic esters, amines and amides. The reactionis not sensitive to moisture or air, and the isolation of the products is operationally simple. The 1,2-bis-alkylidenecycloalkane products display very interesting stereochemical fearf and stannyl groups are pointing toward each other, despite the apparent steric hindrance thus generated. Second, this stereochemistry of the individual double-bonds can lead to axial chirality in the diene system. It has been shown that the 1,2-bis-alkylidenecycloalkanes are indeed axially chiral at lowtemperatures, but they display a fluxional behavior at room temperature. The coalescence temperatures have been determined for several compounds, ranging from 670ðC to + 20ðC, giving insight into the exchange process and the influence of various substituents. Also, the energies of activation of the exchange process have been determined via NMR Line Shape Analysis for a selected set of compounds. These energies appear to depend not only on the groups on the silicon and the tin, but also on the cyclopentane ring substituents. Free energies of activations in the range of 52.3 to 56.9 kJ.mol-1 were observed. The synthetic applications of these compounds have been the object of preliminary studies. Although many reactions did not yield the desired products, tin-lithium and tin-halogen exchange and epoxidation of the alkenes seem to offer some promise. Diels-Alder reactions of the destannylated products can be carried out in quantitative yield. The first example of a Stille coupling with a vinyl iodide is also described.
Comprehensive Organometallic Chemistry III
Author: Publisher: Elsevier Science
ISBN: 9780080445908
Category : Science
Languages : en
Pages : 924
Book Description
Comprehensive Organometallic Chemistry, (COMC-III), Third Edition, 13 Volume Set is aimed at the specialist and non-specialist alike. It covers the major developments in the field in a carefully presented way with extensive cross-references. COMC-III provides a clear and comprehensive overview of developments since 1993 and attempts to predict trends in the field over the next ten years. Applications of organometallic chemistry continue to expand and this has been reflected by the significant increase in the number of volumes devoted to applications in COMC-III. Organic chemists have edited the volumes on organometallic chemistry towards organic synthesis - this is now organized by reaction type so as to be readily accessible to the organic community. Like its predecessors, COMC (1982) and COMC-II (1995), this new work is the essential reference text for any chemist or technologist who needs to use or apply organometallic compounds. Also available online via ScienceDirect (2006) - featuring extensive browsing, searching, and internal cross-referencing between articles in the work, plus dynamic linking to journal articles and abstract databases, making navigation flexible and easy. For more information, pricing options and availability visit www.info.sciencedirect.com. Presents a comprehensive overview of the major developments in the field since 1993 providing general and significant insights Highlights the expansion of applications in organometallic chemistry with a strong organic synthesis focus Provides a structured first point of entry to the key literature and background material for those planning research, teaching and writing about the area