Download or read book THE DEVELOPMENT AND APPLICATION OF NEW PALLADIUM CATALYSTS IN CHALLENGING C N AND C O BOND FORMING REACTIONS written by Christopher B. Lavery and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Development and Application of Palladium catalyzed Carbon nitrogen Bond Forming Reactions written by Seble-Hiwot Teshome Wagaw and published by . This book was released on 1999 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Amination and Formation of sp2 C N Bonds written by Marc Taillefer and published by Springer. This book was released on 2014-01-02 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Palladium-Catalyzed sp2C–N Bond Forming Reactions: Recent Developments and Applications. Metal-catalyzed C(sp2)-N bond formation.- Recent Developments in Recyclable Copper Catalyst Systems for C−N Bond Forming Cross-Coupling Reactions Using Aryl Halides and Arylboronic Acids. Assembly of N-containing heterocycles via Pd and Cu-catalyzed C-N bond formation reactions. Copper-Catalyzed C(aryl)-N Bond Formation.

Download or read book Late Transition Metal Catalyzed C N and C C Bond Forming Reactions written by John Perry Wolfe and published by . This book was released on 1999 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nickel and Palladium Catalyzed Cross Coupling Reactions written by Rebecca Green and published by . This book was released on 2016 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: The following dissertation discusses the development of a nickel catalyst for the synthesis of Csp2-Csp bonds in addition to the development and mechanistic studies of nickel and palladium catalysts for the synthesis of Csp2-N bonds. The first chapter is a review of the cross-coupling reactions discussed in this dissertation. Nickel and palladium will be compared with respect to physical properties and reactivity differences. The challenges associated with nickel-catalyzed cross coupling will be illustrated, while drawing analogies to analogous palladium-catalyzed reactions. The literature background for the synthesis of Csp2-Csp bonds, catalyzed by palladium and palladium/copper catalytic systems, will be reviewed, while highlighting the challenges and limitations of the field. The field of Csp2-N bond-forming reactions will be examined, as the differences in reactivity between nickel and palladium will be emphasized. Chapter 2 discusses our efforts towards the development of a nickel catalyst for the development of a Csp2-Csp bond forming reaction, performed in the absence of a copper co-catalyst. Chapter 3 describes the development of a single-component nickel complex that catalyzes the coupling of aryl chlorides with primary alkylamines. A series of mechanistic experiments, including synthesis of catalytic intermediates and kinetic experiments, were performed to elucidate the mechanism of the reaction. Chapter 4 discusses our report the palladium-catalyzed coupling of aryl halides withammonia and gaseous amines as their ammonium salts. A difference in selectivity between reactions of aryl chlorides and aryl bromides was discovered and investigated. Chapter 5 describes the development of a single-component nickel catalyst for the coupling of aryl chlorides with ammonia and ammonium sulfate to form the corresponding primary arylamines. The application of ammonium salts was extended to the coupling of gaseous amines, such as methylamine and ethylamine, which were subjected to the reaction conditions as their hydrochloride salt.

Download or read book Palladium catalyzed C N Cross coupling Reactions Toward the Synthesis of Drug like Molecules written by Camille Z. McAvoy and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of methodologies for C-N bond formation reactions is an important scientific challenge because of many academic and industrial applications. This work will focus particularly on palladium-catalyzed cross-couplings of amine-containing compounds with aryl halides. The scope of the BrettPhos precatalyst for the cross-coupling of ortho-substituted aryl iodides with amides is studied using substrates with a variety of functional groups. Due to potential metal-chelating issues with some of the substrates used in this study, a proposed ligand synthesis is discussed in which one of the methoxy groups of BrettPhos is replaced with a morpholine capable of occupying palladium's open coordination site during its catalytic cycle. A final C-N bond formation study focuses on the cross-coupling of aryl halides with amidine salts. For this cross-coupling, a methodology has been developed that can be applied to various electron-rich, electron-poor, and electron-neutral substrates. Furthermore, the products of this cross-coupling can be used for a subsequent electrocyclization through a reaction with aldehyde, demonstrating that a relatively simple two-pot methodology can be used to make relatively complex substrates with pharmaceutical applications. Both amides and amidines are common moieties in drug-like molecules because of the various biological activities of these functional groups. Potential medicinal applications of the developed cross-coupling of amidine salts with aryl halides methodology are described. Thus, methodologies for various palladium-catalyzed, C-N cross-couplings as well as a potential ligand synthesis to be used for palladium catalysis are herein discussed.

Download or read book Development and Applications of Pd Catalysts for C N Cross Coupling Reactions written by Brett P. Fors and published by . This book was released on 2011 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 1 A procedure for forming a highly active Pd(0) catalyst from Pd(OAc) 2, water, and biarylphosphine ligands has been developed. This protocol generates a catalyst system, which exhibits excellent reactivity and efficiency in the coupling of a variety of amides and anilines with aryl chlorides. Chapter 2 A new class of one-component Pd precatalysts bearing biarylphosphine ligands is described. These precatalysts are air- and thermally-stable, are easily-activated under normal reaction conditions at or below room temperature, and ensure the formation of the highly-active mono-ligated Pd(0) complex necessary for oxidative addition. The use of these precatalysts as a convenient source of LPd(0) in C-N cross-coupling reactions is explored. The reactivity that is demonstrated in this study is unprecedented in palladium chemistry. Chapter 3 A catalyst system based on a new biarylphosphine ligand that shows excellent reactivity for C-N cross-coupling reactions is reported. This catalyst system enables the use of aryl mesylates as a coupling partner in C-N bond-forming reactions. Additionally, the use of this ligand permits the highly selective monoarylation of an array of primary aliphatic amines and anilines at low catalyst loadings and with fast reaction times, including the first monoarylation of methylamine. Lastly, oxidative addition complexes based on the new ligand are included, which provide insight into the origin of reactivity for this system. Chapter 4 An investigation into the Pd-catalyzed C-N cross-coupling reactions of aryl iodides is described. Neal is shown to have a significant inhibitory effect on these processes. By switching to a solvent system in which the iodide byproduct was insoluble, reactions of aryl iodides were accomplished with the same efficiencies as aryl chlorides and bromides. Using catalyst systems based on certain biarylphosphine ligands, aryl iodides were successfully reacted with an array of primary and secondary amines in high yields. Lastly, reactions of heteroarylamines and heteroaryliodides were also conducted in high yields. Chapter 5 A catalyst based on a new biarylphosphine ligand for the Pd-catalyzed cross-coupling reactions of amides and aryl chlorides is described. This system shows the highest turnover frequencies reported to date for these reactions, especially for aryl chloride substrates bearing an ortho substituent. An array of amides and aryl chlorides were successfully reacted in good to excellent yields. Chapter 6. An efficient Pd-catalyst for the transformation of aryl chlorides, triflates and nonaflates to nitroaromatics has been developed. This reaction proceeds under weekly basic conditions and displays a broad scope and excellent functional group compatibility. Moreover, this method allows for the synthesis of aromatic nitro compounds that cannot be accessed efficiently via other nitration protocols. Mechanistic insight into the trasmetallation step of the catalytic process is also reported. Chapter 7. An alternative approach to catalyst development, which led to a Pd catalyst based on two biarylphosphine ligands for C-N cross-coupling reactions, is reported. By effectively being able to take the form of multiple catalysts this system manifests the best properties that catalysts based on either of the two ligands exhibit separately and displays the highest reactivity and substrate scope of any system that has been reported to date for these reactions.

Download or read book Developments and Applications of Methods for Palladium and Copper catalyzed Carbon nitrogen Bond Formation written by Jeffrey Chih-Yeh Yang and published by . This book was released on 2018 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: The studies presented in this dissertation are aimed at the development and application of methodologies that enable carbon-nitrogen (C-N) bond formation catalyzed by late transition metals such as palladium and copper. The first part of this thesis focuses on the use of palladium catalysis for the construction of a carbon(sp2)-nitrogen bond in the context of a biphasic continuous-flow system (Chapter 1). The second part of this thesis describes the recent developments of copper-hydride (CuH) catalyzed asymmetric hydroamination for the formation of a-chiral carbon(sp3)-nitrogen bonds from olefins. This work includes the application of CuH catalysis to the synthesis of chiral N-alkyl aziridines (Chapter 2), and the discovery and development of novel electrophilic amines to enable CuH-catalyzed asymmetric hydroamination to directly access primary amines (Chapter 3). Part I. Chapter 1. Use of a "Catalytic" Cosolvent, N,N-Dimethyl Octanamide, Allows the Flow Synthesis of Imatinib with no Solvent Switch A general, efficient method for C-N cross-coupling has been developed using N,N-dimethyloctanamide as a cosolvent for biphasic continuous-flow applications. In addition to utilizing a proper co-solvent, the described method harnesses the superior mixing abilities of a stainless-steel powder packed tube reactor to efficiently couple a wide range of aryl/heteroaryl halides and aryl/heteroaryl/alkyl amines in a short period of time (

Download or read book Palladium catalyzed C N and C O Cross coupling Reactions written by Paula Ruiz-Castillo and published by . This book was released on 2016 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 1: This chapter describes a general method for the of the Pd-catalyzed N-arylation of hindered [alpha],[alpha],[alpha]-trisubstituted primary amines. The reaction utilized catalysts based on two biaryl phosphine ligands, which were developed via kinetics-based mechanistic analysis and rational design. These studies led to the first example of catalyst based on a hybrid (alkyl)aryl biaryl phosphine ligand that provides better results that its dialkyl- or diarylbiaryl analogues. The C-N coupling was efficient for a wide range of (hetero)aryl chlorides and bromides under mild conditions. Chapter 2: This chapter relates the development of the Pd-catalyzed C-O coupling of primary alkyl alcohols. The reaction of primary aliphatic alcohols bearing [beta]-hydrogen atoms can lead to undesired [beta]-hydride elimination pathways instead of the target reductive elimination from the [LPd(Ar)OAlk] intermediate, especially when using electron-rich aryl halides. Additionally, aryl chlorides have been shown to be more challenging coupling partners than the corresponding aryl bromides. The use of catalysts based on commercially available ligand t-BuBrettPhos and a novel hybrid ligand, AdCyBrettPhos, have allowed the C-O coupling reaction to proceed effectively at room temperature, minimizing the side reaction. A variety of functionalized primary alcohols have been successfully coupled with (hetero)aryl bromides and chlorides giving rise to medicinally interesting products. Chapter 3: This chapter is a compilation of the applications of Pd-catalyzed C-N coupling in various fields of chemical research since 2008. This work includes the reactions of nine classes of nitrogen-based coupling partners in the 1) synthesis of heterocycles, 2) medicinal chemistry, 3) process chemistry, 4) synthesis of natural products, 5) organic materials and chemical biology, and 6) synthesis of ligands. The large number of applications highlights the versatility and utility of this transformation both in academic and industrial settings.

Download or read book Palladium Catalyzed Coupling Reactions written by Árpád Molnár and published by John Wiley & Sons. This book was released on 2013-02-14 with total page 531 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook and ready reference brings together all significant issues of practical importance in selected topics discussing recent significant achievements for interested readers in one single volume. While covering homogeneous and heterogeneous catalysis, the text is unique in focusing on such important aspects as using different reaction media, microwave techniques or catalyst recycling. It also provides a comprehensive treatment of key issues of modern-day coupling reactions having emerged and matured in recent years and emphasizes those topics that show potential for future development, such as continuous flow systems, water as a reaction medium, and catalyst immobilization, among others. With its inclusion of large-scale applications in the pharmaceutical industry, this will equally be of great interest to industrial chemists. From the contents * Palladium-Catalyzed Cross-Coupling Reactions - A General Introduction * High-turnover Heterogeneous Palladium Catalysts in Coupling Reactions: the Case of Pd Loaded on Dealuminated Y Zeolites Palladium-Catalyzed Coupling Reactions with Magnetically Separable Nanocatalysts * The Use of Ordered Porous Solids as Support Materials in Palladium-Catalyzed Cross-Coupling Reactions * Coupling Reactions Induced by Polymer-Supported Catalysts * Coupling Reactions in Ionic Liquids * Cross-Coupling Reactions in Aqueous Media * Microwave-Assisted Synthesis in C-C and C-Heteroatom Coupling Reactions * Catalyst Recycling in Palladium-Catalyzed Carbon-Carbon Coupling Reactions * Nature of the True Catalytic Species in Carbon-Carbon Coupling Reactions with * Heterogeneous Palladium Precatalysts * Coupling Reactions in Continuous Flow Systems * Large-Scale Applications of Palladium-Catalyzed Couplings in the Pharmaceutical Industry

Download or read book Advances in the Stille Reaction and New Methods for Continuous Flow Pd catalyzed C N Bond Forming Reactions written by John Robert Naber and published by . This book was released on 2010 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 1: A highly active catalyst system based upon a biaryl monophosphine ligand, XPhos, for the palladium-catalyzed Stille reaction has been developed. This method allows for the coupling of aryl chlorides with a range of tributylarylstannanes to produce the corresponding biaryl compounds in good to excellent yields (61-98%) in short reaction times (4 h). Palladium(II) acetate [Pd(OAc)2] and XPhos in a 1:1.1 ratio were milled into a fine powder that was used as pre-catalyst for these reactions. Chapter 2: A catalyst system for the Stille cross-coupling reactions of aryl mesylates and tosylates is reported. Using the combination of Pd(OAc)2, XPhos, and CsF in t-BuOH an array of aryl and heteroaryl sulfonates were successfully employed in these reactions. Morever, heteroarylstannanes, such as furyl, thienyl, and N-methylpyrrolyl, which are often prone to decomposition, were efficiently coupled under these conditions. Ortho-substitution on the stannane coupling partner was well tolerated; however, the presence of ortho substituents on the aryl sulfonates greatly reduced the efficiency of these reactions. Chapter 3: A continuous-flow, multistep Heck synthesis was made possible by integrating microreactors, liquid-liquid extraction, and microfluidic distillation. The microfluidic distillation enabled solvent exchange from CH2Cl2 in the first reaction step to N, N-dimethylformamide (DMF) in the final reaction step. Chapter 4: A method to mitigate clogging of microsystems during Pd-catalyzed C-N bond-forming reactions under continuous flow conditions was developed. Bridging of particles across the channel and deposition of materials on the walls of the microreactor were both found to be causes that led to clogging and techniques to minimize their effects using sonication were developed. This system allows Pd-catalyzed amination reactions for the formation of a diaryl amines to proceed for extended periods of time without significant pressure increase in the reactor. Chapter 5: A highly efficient method for the Pd-catalyzed coupling of aryl chloride and anilines has been developed. Catalysts based on allyl palladium chloride dimer and BrettPhos, using biphasic reaction conditions of toluene and water with KOH as a base, provided excellent yields for these reactions. The use of a packed bed reactor allowed for these reactions to be run in a continuous flow manner.

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.

Download or read book Palladium Reagents and Catalysts written by Jiro Tsuji and published by John Wiley & Sons. This book was released on 2006-02-08 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jiro Tsuji, one of the pioneers in this field of organic synthesis, provides synthetic organic chemists with a remarkable overview of the many applications of organopalladium chemistry. Tsuji discusses the recent developments in the field as well as the explosive growth over the last five years. Highlighting the most recent discoveries in this rapidly expanding field, the book; Focuses on new aspects of organopalladium chemistry, putting emphasis on synthetic applications Investigates the new perspectives on the synthetic uses of contemporary organopalladium chemistry This volume, together with Innovations in Organic Synthesis, Tsuji's previous title, provides complete coverage of over 40 years of organopalladium chemistry. Palladium Reagents and Catalysts: New Perspectives for the 21st Century is an essential reference source and companion for students, and both industrial and academic research chemists working in organic synthesis, particularly on synthesis of natural products and medicinal compounds. Those studying development of new synthetic methodology and organometallic chemistry will also find this book valuable.

Download or read book The Development of Palladium and Copper catalyzed Transformations for the Asymmetric Synthesis of Biologically Active Small Molecules written by James Thomas Masters and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The continued demand for efficient chemo-, regio-, and stereoselective organic transformations motivates the development of new chemical reactions. Transition metal catalysis represents a powerful method for the construction of carbon-carbon, carbon-hydrogen, and carbon-heteroatom bonds in a highly selective fashion. This dissertation describes the development of several new transition metal-catalyzed organic reactions useful in the preparation of various chiral small molecules, including both fundamental organic "building block" compounds and structurally complex natural products and pharmaceutical agents. We report a new strategy for the synthesis of chiral beta-alkynyl esters, ketones, and sulfones via sequential palladium-catalyzed carbon-carbon bond formation and copper-catalyzed carbon-hydrogen bond formation. The process is operationally straightforward, compatible with a broad range of substrates, and delivers the targets in high yields with excellent levels of enantioselectivity. It is compatible with both oxygen and nitrogen functionality, and this enabled the rapid elaboration of the products into a diverse set of chiral heterocycles. The sequential catalysis protocol was employed in a concise, enantioselective synthesis of AMG 837, a potent agonist of G-protein coupled receptor 40. Recognizing both the biological relevance of chiral alkaloids and the synthetic challenges associated with the construction of quaternary, all-carbon stereocenters, we pursued a palladium-catalyzed asymmetric allylic alkylation that effected carbon-carbon bond formation on prochiral oxindole nucleophiles. Although prior research has demonstrated that allylic alkylation reactions of geminal dicarboxylate electrophiles typically yield branched products as the result of ipso-addition, we identify conditions wherein oxindoles react with a dipivaloyl electrophile to afford linear enol pivalate compounds. A mild hydrolysis reaction converts these products into the aldehyde that formally results from asymmetric conjugate addition to acrolein, a challenging transformation with limited literature precedent. These adducts are established precursors to tricyclic alkaloid scaffolds of pharmaceutical interest. Chiral gamma-heteroatom-substituted cycloalkenones are well-established organic "building blocks" that are widely used in the synthesis of complex molecules. The exposure of meso-1,4-allylic dibenzoates to chiral phosphine-ligated palladium salts in the presence of a potassium nitronate nucleophile promotes a unique oxidative desymmetrization reaction. This process yields enantiopure gamma-benzoyloxy cyclopentenones, cyclohexenones, and cycloheptenones. We describe the elaboration of these products into diverse, enantioenriched oxygen- and nitrogen-substituted cycloalkenones via subsequent palladium-catalyzed allylic alkylation reactions involving heteroatom nucleophiles. Separately, we employ enantiopure gamma-benzoyloxy cyclohexenones in short, asymmetric syntheses of enantio- and diastereomerically diverse epoxyquinoid natural products. We further highlight the utility of palladium catalysis in complex molecule synthesis through the development of a unique, intramolecular carbon-carbon bond-forming reaction that generates a strained enyne and through an asymmetric formal synthesis of aliskiren, a renin inhibitor used in the treatment of hypertension.

Download or read book Applications of Palladium catalysed C N Bond Forming Reactions written by Gareth Neil Brace and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: