Download or read book New Palladium Catalyzed Carbonylative Approaches to Heterocycle and Acid Chloride Synthesis written by Gerardo Martin Torres and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Metal catalyzed carbonylation reactions are heavily exploited in synthetic chemistry. These include not only high volume industrial reactions, but also a plethora of catalytic small molecule syntheses. This thesis will describe our efforts to develop such reactions. In these, palladium catalyzed carbonylations are exploited to build-up reactive products such as acid chlorides or carbonyl-containing 1,3-dipoles. Coupling this with the ability of the products undergo other spontaneous reactions can offer new routes to build up products from combinations of available reagents or be used to expand the scope of carbonylation chemistry. In chapter 2, we describe how the palladium catalyzed carbonylation of aryl iodides in the presence of imines can allow the overall generation of a 1,3-dipole: a Münchnone. A variety of mechanistic studies were performed on this reaction and show that it proceeds via a tandem catalytic process: the first involving the Pd catalyzed coupling of aryl iodides with carbon monoxide and a chloride salt to form an acid chloride, which can react with an imine and then undergo a second spontaneous cyclocarbonylation to afford the product. Coupling their formation with alkyne cycloaddition can be used to develop a novel method to assemble broad families of pyrroles from aryl iodides, imines, carbon monoxide and alkynes. In Chapter 3 we develop a strategy to apply our palladium catalyzed carbonylative synthesis of Münchnones to construct more complex pyrrole structures. In this, the combination of alkyne-tethered imines, aryl iodides, and carbon monoxide generates a Münchnone that can undergo intramolecular 1,3-dipolar cycloaddition to generate polycyclic pyrroles. This approach allows the modular and regioselective synthesis of complex pyrrole structures, and is compatible with less activated alkynes. In addition, we show that this reaction can be used in tandem with the palladium catalyzed Sonogashira functionalization of terminal alkynes with aryl iodides.In Chapter 4 we describe our efforts to take advantage of the ketene-like reactivity of Münchnones to generate [beta]-lactams. This transformation occurs via the palladium catalyzed formation of Münchnones from imines, aryl iodides, and carbon monoxide, followed by a cycloaddition to a second equivalent of imine to afford amide substituted [beta]-lactam products. Moreover, applying the conditions described in Chapter 2 for the synthesis of Münchnones allowed us to construct more diversely substituted [beta]-lactams by reacting the Münchnone with a different imine. Alternatively, the palladium catalyzed carbonylation of imine-tethered aryl iodides leads to the formation of novel spirocyclic [beta]-lactams.The palladium catalyzed synthesis of acid chlorides is a key component to the synthetic approaches to heterocycles presented in Chapters 2-4. However, the specific features that enable the catalyst to mediate the challenging reductive elimination of acid chlorides also inhibit the reverse oxidative addition step. In Chapter 5 we address these limitations by approaching this palladium catalyzed reaction from a different perspective. In this, visible light is used to drive both key steps in palladium catalysis: oxidative addition and reductive elimination. Analogous to other reports, we show that visible light excitation of a Pd complex can drive oxidative addition of a wide variety of aryl and alkyl halides. In addition, we find that visible light can induce a new reaction step the reductive elimination of acid chlorides. The latter occurs via the excitation in this case of the palladium-acyl intermediate. Together, this offers a platform to perform palladium catalyzed carbonylations at ambient temperature, with a wide array of organic halide substrates that have proven to be challenging in traditional palladium catalysis, and form from these acid chloride electrophiles that can allow the use of nucleophiles that are typically incompatible with carbonylations"--

Download or read book Palladium Catacyzed Carbonylative Approaches to Acyl Electrophiles Using Ligand Effects Or Visible Light written by Yi Liu and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Transition metal catalyzed carbonylation reactions have been broadly exploited for the synthesis of carbonyl-containing products. A versatile version of these are palladium-catalyzed carbonylative coupling reactions of organic halides and nucleophiles. However, one drawback to this chemistry is the low electrophilic reactivity of the palladium-acyl intermediates in reaction, which severely limits the scope of nucleophiles that can be employed in carbonylations. This thesis describes studies to address this challenge by the formation of potent acyl electrophiles via metal-catalyzed carbonylations, and their use with non-classical carbonylation nucleophiles. In chapter 2, we demonstrate how the correctly ligated palladium catalyst can be used to create potent acyl-pyridinium electrophiles via the carbonylation of aryl or vinyl triflates, and use these for in situ (hetero)arene C-H bond functionalization. The reaction was catalyzed by a Xantphos-coordinated palladium catalyst, and the bidentate and large-bite-angle ligand is believed to balance the activation of the strong C(sp2)-OTf bonds with the reductive elimination of reactive N-acyl-pyridinium electrophiles. The pyridine employed not only leads to the formation of the acyl-pyridinium salt electrophile, but its structure can be used to modulate selectivity in arene C-H functionalization. Overall, this offers a carbonylative method to form diaryl ketones, [alpha],[beta]-unsaturated ketones, and polycyclic ketones using a broad range of aryl- or vinyl- triflates and (hetero)arenes. Chapter 3 describes an extension of the work in chapter 2, where simple lithium chloride rather than the specialized trifluoromethyl- or methoxy-substituted pyridine can be used as the additive for the palladium catalyzed carbonylative coupling of aryl or vinyl triflates and heteroarenes to form ketones. Mechanistic studies suggest the reaction proceeds by the catalytic generation of acid chloride electrophiles for functionalization of electron-rich heterocycles.A limitation to the carbonylative generation of acyl electrophiles noted above is the need to use aryl- or vinyl-(pseudo)halides as reagents. The association of carbon monoxide to the catalyst severely inhibits oxidative addition reactions, and blocks the use of less reactive substrates such as alkyl halides. In chapter 4, we design a strategy to address these challenges using visible light excitation of palladium. This has opened an approach to perform the carbonylation of diverse array of aryl- and even alkyl-halides and from these build-up acid chlorides with the ability to reaction with various nucleophiles. Mechanistic studies suggest the reaction proceeds via a unique combination of photoevents, where the photoexcitation of Pd(0) induces electron transfer with the organic halide to favor oxidative addition, while the photoexcitation of the Pd(II) intermediate leads to Pd-acyl bond scission and the ultimate reductive elimination of acid chloride electrophiles. While the results in chapter 4 expand the variety of products available from carbonylation, the formation of acid chlorides as reaction products (rather than intermediates) is usually not possible. The latter can be attributed to the high reactivity of acid chlorides, which can lead to their rapid re-addition to the palladium catalyst and either inhibit the reaction or lead to their slow decomposition. In chapter 5, we developed a method to address these limits via the synthesis of less easily reduced acyl fluorides. In this case, mechanistic studies suggest visible light favored oxidative addition to Pd(0) is coupled with rapid ligand driven reductive elimination of the acyl fluoride product, which does not re-add to the Pd(0) once formed. By driving these two reverse steps with different inputs, this has offered a general platform to access acyl fluoride electrophiles, and from these synthesize complex, highly functionalized carbonyl-containing products"--

Download or read book Palladium catalyzed Carbonylative Synthesis of Acid Chorides and Use in Multicomponent Coupling Reactions written by Jeffrey Quesnel and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "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. " --

Download or read book Palladium catalyzed Carbonylative and Decarbonylative Transformations for the Synthesis of Reactive Electrophiles and Heterocycles written by Maximiliano De La Higuera Macias and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The palladium catalyzed carbonylation of aryl halides can provide a useful method to synthesize carbonyl containing products. This thesis describes the development of two new variants of such reactions that offer efficient routes to generate either reactive electrophiles or heterocycles. These reactions can be performed using commercially available reagents, which include aryl iodides, imines, acid chlorides and carbon monoxide. Chapter 2 describes the development of a new method to utilize palladium catalysis to generate reactive acid chloride electrophiles. This transformation occurs via the metathesis of covalent [sigma]-bonds between Ar-X fragments, and demonstrates the dynamic nature of palladium-based oxidative addition/reductive elimination. Overall, this opens a route to synthesize acid chlorides without the use of high energy corrosive or toxic reagents, and instead from exchange with other acid chlorides. Coupling the in-situ formation of acid chlorides with nucleophiles allows the efficient synthesis of a number of carbonyl containing compounds. Chapter 3 describes the development of a new palladium catalyzed multicomponent synthesis of spirocyclic-[beta]-lactams. This reaction proceeds via two tandem catalytic carbonylation reactions, where a single palladium catalyst mediates the formation of acid chlorides, [alpha]-chloroamides and ketenes as intermediates. Subsequent trapping of the ketene by [2+2] cycloaddition reactions furnishes the polysubstituted product. The transformation provides a route to generate a number of spirocyclic-[beta]-lactams from imine-tethered aryl iodides, imines and CO." --

Download or read book Development of New Classes of Palladium and Nickel Catalyzed Carbonylation Reactions written by Jevgenijs Tjutrins and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis describes the development of new palladium and nickel catalyzed carbonylation reactions to efficiently and rapidly generate products with minimal waste. These reactions can be carried out using commercially and/or readily available starting materials, including imines, acid chlorides, aryl iodides, alkynes, alkenes and carbon monoxide. In chapter 2, we describe a palladium catalyzed carbonylative synthesis of polysubstituted imidazoles. This transformation involves a tandem catalytic process, where a single palladium catalyst mediates both the carbonylation of aryl halides to form acid chlorides, as well as cyclocarbonylation of a-chloroamides, to generate 1,3-dipoles. Finally, a regioselective 1,3-dipolar cycloaddition with electron poor imines furnishes tetra-substituted imidazoles. Overall this provides a route to prepare imidazoles from five readily available building blocks: two electronically distinct imines, aryl halides and two molecules of CO. In chapter 3, we describe a nickel catalyzed approach to synthesize of isoindolinones via the carbonylation of aryl iodides in the presence of imines. In this, the nickel catalyzed in situ generation of acid chlorides via aryl halide carbonylation allows the formation of a chloroamides, which in turn undergo an intramolecular cyclization to form isoindolinones. This reaction offers an efficient alternative to traditional syntheses of isoindolinones, which often require the initial assembly of the appropriate aryl-tethered precursors for cyclization. In chapter 4, we describe the development of a palladium catalyzed, electrophilic approach to the carbonylative C-H bond functionalization of a range of heterocycles. Mechanistic studies show that the Pd/PtBu3 catalyst can mediate the in situ formation of highly electrophilic aroyl iodide intermediates, which react with heterocycles forming aryl-(hetero)aryl ketones. This provides a general methodology to construct ketones from aryl iodides and electron rich heterocycles without the need to prefunctionalize the heterocycle, install directing groups, or exploit high energy starting materials (e.g. acid chlorides). Chapter 5 describes mechanistic studies on the palladium catalyzed multicomponent synthesis of 1,3-oxazolium-5-olates (Münchnones). Previous work in our laboratory has shown that Münchnones can be generated via the palladium catalyzed multicomponent coupling of acid chlorides, imines and CO. In order to better understand this reaction, we synthesized and characterized key reactive intermediates, studied stoichiometric model reactions, and performed kinetic studies on catalytic reaction. These allowed the elucidation of the role of the catalyst structure, rate determining steps, as well as the importance of off cycle steps in this transformation. In chapter 6, we show how the mechanistic insights laid out in the previous chapter can be applied to create a highly active catalytic system for synthesis of 1,3-oxazolium-5-olates. By employing a sterically encumbered pyrrole-based phosphine ligand, which can be more easily displaced by carbon monoxide for carbonylation, we have created a catalyst that is more than ten times more active that previous systems for this reaction. When coupled with alkyne cycloaddition, this offers a broadly generalizable route to form polysubstituted pyrroles from simple imines, acid chlorides and alkynes. This approach has been applied to the multicomponent synthesis of Atorvastatin (i.e., Lipitor). " --

Download or read book Palladium in Heterocyclic Chemistry written by Jie Jack Li and published by Elsevier. This book was released on 2006-10-20 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt: Palladium chemistry, despite its immaturity, has rapidly become an indispensable tool for synthetic organic chemists. Heterocycles are of paramount importance in the pharmaceutical industry and palladium chemistry is one of the most novel and efficient ways of making heterocycles. Today, palladium-catalyzed coupling is the method of choice for the synthesis of a wide range of biaryls and heterobiaryls. The number of applications of palladium chemistry to the syntheses of heterocycles has grown exponentially. These developments highlight the need for a monograph dedicated solely to the palladium chemistry in heterocycles and this book provides a comprehensive explanation of the subject. The principal aim of the book is to highlight important palladium-mediated reactions of heterocycles with emphasis on the unique characteristics of individual heterocycles. 1. Palladium chemistry of heterocycles has its “idiosyncrasies stemming from their different structural properties from the corresponding carbocyclic aryl compounds. Even activated chloroheterocycles are sufficiently reactive to undergo Pd-catalyzed reactions. As a consequence of &agr and &bgr activation of heteroaryl halides, Pd-catalyzed chemistry may take place regioselectively at the activated positions, a phenomenon rarely seen in carbocyclic aryl halides. In addition, another salient peculiarity in palladium chemistry of heterocycles is the so-called "heteroaryl Heck reaction". For instance, while intermolecular palladium-catalyzed arylations of carbocyclic arenes are rare, palladium-catalyzed arylations of azoles and many other heterocycles readily take place. Therefore, the principal aim of this book is to highlight important palladium-mediated reactions of heterocycles with emphasis on the unique characteristics of individual heterocycles. 2. A myriad of heterocycles are biologically active and therefore of paramount importance to medicinal and agricultural chemists. Many heterocycle-containing natural products (they are highlighted in boxes throughout the text) have elicited great interest from both academic and industrial research groups. Recognizing the similarities between the palladium chemistry of arenes and heteroarenes, a critical survey of the accomplishments in heterocyclic chemistry will keep readers abreast of such a fast-growing field. We also hope this book will spur more interest and inspire ideas in such an extremely useful area. This book comprises a compilation of important preparations of heteroaryl halides, boranes and stannanes for each heterocycle. The large body of data regarding palladium-mediated polymerization of heterocycles in material chemistry is not focused here; neither is coordination chemistry involving palladium and heterocycles. Many heterocycle-containing natural products (highlighted throughout the text) have elicited great interest from both academic and industrial research groups. Recognizing the similarities between the palladium chemistry of arenes and heteroarenes, a critical survey of the accomplishments in heterocyclic chemistry keeps readers abreast of this fast-growing field. It is also hoped that this book will stimulate more interest and inspire new ideas in this exciting area. Contains the most up-to-date developments in this fast-moving field Includes 3 new chapters Incorporates material from selected well-respected authors on heterocyclic chemistry

Download or read book New Palladium catalyzed Approaches to Heterocycles and Carbocycles written by Guangxiu Dai and published by . This book was released on 2003 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt: A wide variety of 3,4-disubstituted isoquinolines containing an aryl, allylic, benzylic, alkynyl and vinylic group at the 4 position have been prepared via cross-coupling of 2-(1-alkynyl)benzaldimines with organic halides in the presence of a palladium catalyst. The best results are obtained by employing 5 mol % Pd(PPh3)4, 5 equiv of K2CO3 in DMF at 100°C. The electronic effect of the imine substrates and organic halides on the yields has been discussed. 3-Substituted 4-aroylisoquinolines have been prepared in high yields via carbonylative cross-coupling of 2-(1-alkynyl)benzaldimines with aromatic iodides or aroyl chlorides in the presence of a palladium catalyst under 1 atm of CO pressure. Imine substrates having an aryl, vinylic or alkyl substituent on the distal end of the triple bond all undergo this palladium-catalyzed carbonylative cross-coupling cyclization in high yields. The palladium(II)-catalyzed oxidative carbonylation of 2-(1-alkynyl)benzaldimines for synthesis of the corresponding isoquinoline-4-carboxylates has been studied and the optimal reaction conditions have been investigated. Although this methodology study has not provided an efficient route to synthesize methyl 3-substituted isoquinoline-4-carboxylates in synthetically useful yields, it provides an insight into the nature of the palladium-catalyzed cyclization reactions promoted by organopalladium intermediates. A novel intramolecular alkyl-to-aryl palladium rearrangement has been observed by trapping the arylpalladium intermediate with an olefin by a Heck reaction. The reaction conditions have been optimized and the reaction scope has been extensively studied. In all of the successful examples, migration products were isolated exclusively. In addition, this alkyl-to-aryl palladium migration can be controlled by simply modifying the reaction conditions.

Download or read book Palladium Assisted Synthesis of Heterocycles written by Navjeet Kaur and published by CRC Press. This book was released on 2019-05-01 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book New Palladium catalyzed Approaches to Heterocycles and Carbocycles written by Qinhua Huang and published by . This book was released on 2004 with total page 629 pages. Available in PDF, EPUB and Kindle. Book excerpt: The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I2, ICl, PhSeCl, and p-O2NC6H4SCl to give the corresponding halogen-, selenium-, and sulfur containing disubstituted isoquinolines and naphthyridines, respectively. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. The Pd(II)-catalyzed cyclization of 2-(1-alkynyl)arylaldimines in the presence of various alkenes provides an efficient way to synthesize a variety of 4-(1-alkenyl)-3-arylisoquinolines in moderate to excellent yields. The introduction of an ortho-methoxy group on the arylaldimine promotes the Pd-catalyzed cyclization and stabilizes the resulting Pd(II) intermediate, improving the yields of the isoquinoline products. Highly substituted naphthalenes have been synthesized by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields. Novel palladium migration/arylation methodology for the synthesis of complex fused polycycles has been developed, in which one or more sequential Pd-catalyzed intramolecular migration processes involving C-H activation are employed. The chemistry works best with electron-rich aromatics, which is in agreement with the idea that these palladium-catalyzed C-H activation reactions parallel electrophilic aromatic substitution. A relatively efficient synthesis of cyclopropanes has been developed using palladium-catalyzed C-H activation chemistry, in which two new carbon-carbon bonds are formed in a single step. This method involves the palladium-catalyzed activation of relatively unreactive C-H bonds, and provides a very efficient way to synthesize cyclopropapyrrolo[1,2-a]indoles, analogues of the mitomycin antibiotics.

Download or read book Palladium catalyzed Heterocycles Synthesis Via Carbonylative Activation of Ar X and Ar H Bonds written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Palladium and Electrophilic Cyclization Approaches to Carbo and Heterocyclic Compounds written by Dawei Yue and published by . This book was released on 2004 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation the scope and limitations of several electrophilic cyclization processes have been presented. In particular, electrophilic cyclization has been used for the synthesis of a variety of heterocycles, including benzo[b]furans, isochromenes, dihydroisoquinolines, isobenzofurans and coumestans. An unusual palladium migration has also been explored and applied to the synthesis of fluoren-9-ones. Chapter 1 describes the synthesis of 2,3-disubstituted benzo[b]furans by the palladium-catalyzed coupling and electrophilic cyclization of terminal alkynes. A highly chemoselective electrophilic cyclization has been achieved by carefully choosing the protecting group on the oxygen functionality. Various electrophiles, such as I2, Br2, PhSeCl and p-O2NC6H4SCl, can be used to introduce different functionalities into the desired cyclization products. Chapter 2 presents the synthesis of heterocycles by electrophilic cyclization reactions of acetylenic aldehydes, ketones and imines. The overall synthetic process involves the coupling of a terminal acetylene with o-iodoarenecarboxaldehydes or ketones by a palladium-catalyzed coupling reaction, followed by electrophilic cyclization with various electrophiles in the presence of proper nucleophiles. Oxygen- and nitrogen-containing heterocycles can be quickly assembled by this three component process in good to excellent yields. Chaper 3 describes the synthesis of coumestan and coumestrol by selective electrophilic cyclization, followed by palladium-catalyzed intramolecular carbonylation and lactonization. The biologically interesting coumestan system can be quickly constructed by this very efficient approach from common starting materials. The palladium-catalyzed reaction effects as both carbonylation and lactonization in one step. Chapter 4 examines the scope and synthetic utility of a 1,4-Pd through space migration. The synthesis of various fluoren-9-ones has been accomplished by the Pd-catalyzed intramolecular C-H activation of imines derived from 2-iodoaniline and biarylcarboxaldehydes. This methodology makes use of a novel 1,4-palladium migration from an aryl position to an imidoyl position to generate the key imidoyl palladium intermediate, which undergoes intramolecular arylation to produce imines of complex polycyclic compounds containing the fluoren-9-one core structure. Both electronic effects and steric effects have been investigated.

Download or read book Carbonylation written by H.M. Colquhoun and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the publication of our earlier book on transition metal mediated organic synthesis, * there has been a widespread increase of interest in this topic, and transition metal based methodology has become firmly established in many areas of organic chemistry. The direct, catalytic formation of organic carbonyl compounds using carbon monoxide as the source of the carbonyl group has seen exceptional progress, and this carbonylation chemistry is being used increasingly in research and on a larger scale for fine chemicals production. In view of these developments, there is a need for a modem, practi cally oriented book dealing with transition metal based carbonylation chemistry. The present monograph should help fulfill this need, since it is intended specifically to foster the adoption of catalytic carbonylation as a general tool in synthetic organic chemistry. It deals exclusively with reactions involving the interconversion of carbon monoxide and organic carbonyl compounds, and although the majority of the reactions discussed involve catalytic formation of carbonyl compounds, potentially valuable syntheses requiring stoichiometric quantities of transition metal are also included. In addition, a chapter is devoted to the remarkably useful reverse transformation (decarbonylation), in which an organic carbonyl group is eliminated in the form of carbon monoxide.

Download or read book Palladium catalyzed Carbonylative Synthesis of Carboxylic Acid Anhydrides from Alkenes written by and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Palladium catalyzed Carbonylation Reactions of Aryl Halides written by Yang Yuan and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is focused on the development of palladium-catalyzed carbonylation of aryl chlorides and the development of new nucleophiles in palladium-catalyzed carbonylation of aryl halides. Due to the importance of the corresponding carbonyl products both for organic synthesis and chemical industries, new and practical synthetic methods are presented. Specifically, an efficient synthesis of pyrido-fused quinazolinones and dibenzoxazepinones by palladium-catalyzed carbonylation/nucleophilic aromatic substitution reaction from 1-chloro-2-fluorobenzenes and 2-aminopyridines is presented.eng

Download or read book The Design of Palladium and Copper catalyzed Atom Economical Reactions written by Boran Xu and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis describes the development of novel metal-catalyzed reactions in two different areas: palladium-catalyzed multicomponent coupling reactions, and copper-catalyzed aerobic oxidations of alcohols and amines. The goal of this work is to discover efficient processes to rapidly generate useful products with minimal waste. In chapter 2, we describe a straightforward new synthesis of 2-imidazolines. This reaction couples the palladium-catalyzed multicomponent formation of 2-imidazolium carboxylates, with subsequent decarboxylation. Polysubstituted imidazolines have useful applications in therapeutics, but are typically prepared in a multistep sequence. We report that the use benzoic acid and water as additives affords good yields and diastereoselectivities for the decarboxylation step. Combining this reaction with subsequent nitrogen deprotection, allows access to imidazolines from four available reagents: two imines, an acid chloride and CO. In chapter 3, we describe the three component palladium-catalyzed synthesis of [alpha]-amidostannanes from imines, acid chlorides and a bis-stannane. The reaction affords product in good yields, proceeds in 1 h, and uses simple Pd2(dba)3 as the catalyst. Mechanistically, this transformation occurs via a Stille-type cross-coupling of an in situ generated iminium salt with the bis-stannane. This represents a mild alternative to traditional syntheses of these products, with strong nucleophilic reagents. Subsequent lithiation and carboxylation can generate various [alpha]-amino acid derivatives in two steps from imines, acid chlorides and CO2. In chapter 4, we describe the copper-catalyzed aerobic oxidation of alcohols without the use nitroxyl co-catalysts. We demonstrate that a Cu/di-tert-butylethylenediamine (DBED) catalyst can generate active copper-oxygen species capable of mediating alcohol oxidation. This catalyst operates at ambient pressure and temperature and retains activity for challenging substrates such as secondary unactivated alcohols. Notably, this system likely operates via a distinct mechanistic pathway compared to nitroxyl based oxidations, and as a result, shows different alcohol chemoselectivity. In chapter 5, we describe the effects of the counterion (X-) in copper-catalyzed aerobic oxidation, and apply these to the oxidation of primary amines. By manipulating the copper salt employed, we have been able to design active catalysts for the oxidation of amines to nitriles (with CuI/DBED), or to imines (with CuPF6). Both of these reactions occur at unusually mild conditions (ambient temperature and pressure), and provide a practical approach to selective amine oxidation without added nitroxyl co-catalysts. " --

Download or read book Carbonylative Ketone Synthesis Via Palladium Catalyzed Generation of N acyl Pyridinium Electrophiles written by Angela Kaiser and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The transition metal catalyzed functionalization of aromatic and aliphatic C-H bonds, commonly referred to as C-H functionalization, has become an area of significant interest as a route to convert feedstock reagents into value-added products. The incorporation of carbon monoxide into these systems is particularly attractive due to both the broad reactivity of carbonyl functionalities, and their abundance in natural products, pharmaceuticals, polymers and other classes of important products. Chapter 1 outlines the development and continued growth of the field of carbonylative C-H functionalization, and those strategies that have found widespread utility. One of the most challenging areas of metal catalyzed carbonylative C-H functionalization is ketone synthesis. To date, these have typically required the use of intramolecular reactions, or substrates possessing acidic C-H bonds. Among the small number of intermolecular C-H functionalization manifolds developed for carbonylative ketone synthesis, most require costly aryl halide substrates and stochiometric metal salt additives. To address these limitations, Chapter 2 presents our design of a palladium catalyzed, intermolecular method for the carbonylative synthesis of aryl ketones from electron rich (hetero)arenes using easily prepared aryl or vinyl triflates. Mechanistic studies suggest that these reactions proceed via the in situ generation of a new class of Friedel-Crafts electrophile, N-acyl pyridinium salts, which can undergo subsequent electrophilic aromatic substitution with (hetero)arene. The catalytic build-up of these acylating agents allows access to a wide range of aryl ketones, does so without stoichiometric metal salts, and with accessible starting materials. In addition, the in situ generated pyridinium salt offers a new avenue to tune reactivity based on the electronic properties of the pyridine employed"--

Download or read book Modern Carbonylation Methods written by László Kollár and published by John Wiley & Sons. This book was released on 2008-06-25 with total page 383 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensively covering modern carbonylation chemistry, this book is an indispensable companion for all synthetic chemists working in industry and academia. This monograph contains everything there is to know from recent advances in the investigation of carbonylation catalysts, via coordination chemistry to the synthetic application of transition metal catalyzed carbonylations.