Download or read book Palladium catalyzed and Electrophilic Cyclization Approaches to Important Heterocycles and Carbocycles written by Saurabh Mehta and published by . This book was released on 2009 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Palladium catalyzed and Electrophilic Cyclization Approaches to Carbocycles and Heterocycles written by Shilpa Arvind Worlikar and published by . This book was released on 2008 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 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 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 Approaches to Heterocycles and Carbocycles written by Tuanli Yao and published by . This book was released on 2005 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electrophilic cyclization of functionally-substituted alkynes is a very promising route to an extraordinary range of medicinally interesting, functionally-substituted heterocycles and carbocycles. For instance, a variety of substituted isocoumarins and [alpha]-pyrones are readily prepared in excellent yields under very mild reaction conditions by the reaction of o-(l-alkynyl)benzoates and (Z)-2-alken-4-ynoates with IC1,I2, PhSeCl, p-O2NC6H4SCl, and HI. This methodology accommodates various alkynyl esters and has been successfully extended to the synthesis of polycyclic aromatic and biaryl compounds. Electrophilic cyclization of o-(l-alkynyl)benzamides with IC1, I2, and NBS, affords a variety of substituted isoindolin-1-ones in good to excellent yields. In a few cases, substituted isoquinolin-1-ones were obtained as the major product instead. This methodology accommodates various alkynyl amides and functional groups, and has been successfully extended to heterocyclic starting materials. This chemistry has been successfully applied to the formal synthesis of a biologically interesting alkaloid cepharanone B.A variety of substituted polycyclic aromatics are readily prepared in good to excellent yields under very mild reaction conditions by the reaction of 2-(1-alkynyl)biphenyls with IC1, I2, NBS, and p-O2NC6H4SCl. This methodology readily accommodates various functional groups and has been successfully extended to systems containing a variety of polycyclic and heterocyclic rings. The coupling of 2-(1-alkynyl)-2-alken-1-ones with nucleophiles, either catalyzed by AuCl3 or induced by an electrophile, provides highly substituted furans in good to excellent yields under very mild reaction conditions. Various nucleophiles, including functionalized alcohols, H2O, carboxylic acids, 1,3-diketones and electron-rich arenes, and a range of cyclic and acyclic 2-(1-alkynyl)-2-alken-1-ones readily participate in these cyclizations. Iodine, NIS, and PhSeCl have proven successful as electrophiles in this process. The resulting iodine-containing furans can be readily elaborated to more complex products using known organopalladium chemistry.

Download or read book Palladium and Iodine Approaches to 1 3 dienes Heterocycles and Carbocycles written by Xiaoxia Zhang and published by . This book was released on 2005 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: A variety of highly-substituted 1,3-dienes and 1,3,5-trienes have been regio- and stereoselectively prepared by the palladium-catalyzed coupling of vinylic iodides, internal alkynes and organoboranes in moderate to good yields. The analogous three-component coupling of aryl halides, 1,3-dienes, and boronic acids provides a useful route to 3,6-disubstituted cyclohexenes. This method is a very concise and efficient way to synthesize these molecules, whose synthesis has previously required multi-step synthesis. A wide variety of substituted quinolines have been readily synthesized under mild reaction conditions by the 6-endo-dig electrophilic cyclization of N-(2-alkynyl)anilines by IC1, I2, Br2 and PhSeBr. The reaction affords 3-halogen-, selenium- and sulfur-containing, and 4-aryl-, alkyl- and vinylic quinolines in moderate to good yields. Quinolines bearing a hydrogen in the 3-position have been synthesized by the Hg(OTf)2-catalyzed ring closure of these same alkynylanilines. Substituted naphthalenes are readily prepared regioselectively under mild reaction conditions by the 6-endo-dig electrophilic cyclization of appropriate arene-containing propargylic alcohols with IC1, I2, Br2, NBS and PhSeBr. 3-Iodo-2-naphthols have also been prepared in excellent yields by the cyclization of analogous l-aryl-3-alkyn-2-ones. This methodology has been successfully extended to the synthesis of substituted carbazoles and dibenzothiophenes and readily accommodates various functional groups. The electrophile-induced intramolecular ipso-cyclization of 4-methoxyaryl alkynes provides an efficient approach to various 3-halogen-substituted spirotrienones under very mild reaction conditions. Substituted spiro[4.5]trienones, l-azaspiro[4.5]trienones, spiro[4.5]diones, l-oxaspiro[4.5]diones, and l-azaspiro[4.5]diones are all readily synthesized. IC1, I2 and Br2 are all effective electrophiles for this process. Arynes generated in situ from 2-(trimethylsilyl)aryl triflates and CsF undergo annulation by o-haloarenecarboxaldehydes in the presence of a Pd catalyst, providing a useful new method for the synthesis of fluoren-9-ones in good yields.

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 Synthesizing Annulated Carbocycles and Heterocycles written by S. Thavaselvan and published by . This book was released on 2023-05-28 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: S. Thavaselvan is a renowned scientist in the field of organic chemistry, particularly in the area of synthesizing annulated carbocycles and heterocycles. In this area of research, he has made significant contributions to the development of new methodologies for the synthesis of complex molecules with diverse biological activities. Synthesis of annulated carbocycles and heterocycles is a challenging task due to the presence of multiple functional groups and the complexity of the reaction pathways involved. However, with the development of new methods and strategies, this area of research has seen rapid growth in recent years. Cyclization reactions, which involve the formation of a ring from a linear precursor, are the most common methods used for the synthesis of annulated carbocycles and heterocycles. These reactions can be catalyzed by a variety of transition metals such as palladium, rhodium, ruthenium, nickel, copper, and iron. The choice of metal catalyst and ligand can significantly influence the outcome of the reaction, particularly with respect to stereoselectivity and regioselectivity. Chiral ligands are used to achieve asymmetric synthesis of annulated carbocycles and heterocycles, while non-chiral ligands are used for stereoselective synthesis. Aromatic and aliphatic compounds can be used as starting materials for the synthesis of these complex molecules, and a range of functional groups including nitrogen, oxygen, and sulfur can be incorporated into the final product. The synthesis of annulated carbocycles and heterocycles can also involve nucleophilic substitution, electrophilic substitution, cross-coupling reactions, ring opening reactions, rearrangement, reduction, and oxidation. Grignard reagents, Sonogashira reaction, Suzuki reaction, and Heck reaction are some of the most commonly used reactions for the synthesis of these compounds. Heteroaromatic compounds such as pyridine, indole, quinoline, pyrimidine, pyrazine, benzofuran, benzothiophene, benzimidazole, isoquinoline, and pyrrole are commonly used as building blocks for the synthesis of annulated carbocycles and heterocycles due to their diverse biological activities. In conclusion, S. Thavaselvan's research in the area of synthesizing annulated carbocycles and heterocycles has contributed significantly to the development of new methodologies for the synthesis of complex molecules with diverse biological activities. The use of different metal catalysts, ligands, and functional groups has enabled the development of efficient and selective synthetic methods for the preparation of these complex molecules.

Download or read book Nickel and Palladium Catalyzed Routes to Carbocycles and Heterocycles written by Ashish Thakur and published by . This book was released on 2015 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Palladium in Heterocyclic Chemistry written by Jie Jack Li and published by Elsevier. This book was released on 2000 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: For this text, Jack Li and Gordon Gribble have compiled an array of referenced examples of the use of palladium in heterocyclic chemistry.

Download or read book Synthesis of Heterocycles and Carbocycles Through Tandem and Domino Palladium catalyzed Reactions written by David Ingoo Chai and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Palladium in Organic Synthesis written by Jiro Tsuji and published by Springer. This book was released on 2010-11-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Palladium is a remarkable metal. In particular, organopalladium chemistry has made remarkable progress over the last 30 years. That progress is still continuing, without any end in sight. This book presents a number of accounts and reviews on the novel Pd-catalyzed reactions discovered mainly in the last five years. The book covers Pd-catalyzed reactions that are new – entirely different from the more standard ones. Topics such as new reactions involving ß-carbon elimination and formation of palladacycles as key reactions, cross-coupling of unactivated alkyl electrophiles with organometallic compounds, arylation via C-H bond cleavage, Pd/norbornene-catalyzed aromatic functionalizations, three-component cyclizations of allenes, use of N-heterocyclic carbenes as ligands, asymmetric reactions catalyzed by Pd(II) compounds such as Lewis acids, cycloadditions of arynes and alkynes, and nucleophilic attack by Pd species are surveyed in detail by researchers who have made important contributions to these fields. The book addresses graduate students majoring in organic synthesis and researchers in academic and industrial institutes.

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 Synthesis of Aromatic Heterocycles and Carbocycles Through Tandem Palladium Catalyzed Cross Coupling Reactions of Gem dihaloolefins written by Christopher Scott Bryan and published by . This book was released on 2010 with total page 798 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our group has developed a strategy for the synthesis of benzofused carbocycles and heterocycles through tandem palladium-catalyzed reactions of gem-dibromoolefins. In these syntheses, one bromide undergoes a Pd-catalyzed cyclization reaction, and the other participates in an orthogonal inter- or intramolecular Pd-catalyzed reaction to functionalize or annulate that ring, respectively.Chapter 2 describes the synthesis of benzothiophenes through the combination of a Pd-catalyzed C--S coupling with an orthogonal Suzuki, Heck, or Sonogashira reaction. This represents the first example of the incorporation of Pd-catalyzed C--S coupling into a tandem reaction.Chapter 1 describes the pairing of an intramolecular C--N bond forming reaction (the Buchwald- Hartwig coupling) with an intramolecular direct arylation for the synthesis of fused indole derivatives. A range of previously unknown heterocycles were synthesized through this method.In Chapter 3, a tandem intramolecular Heck / intermolecular Suzuki reaction is described for the synthesis of methyleneindenes. Studies on this reaction have provided advanced understanding of the mechanism, including how variation of the ligand controls the regioselectivity of the reaction.

Download or read book Synthesis of Aromatic Heterocycles and Carbocycles Through Tandem Palladium catalyzed Cross couplings of Gem dihaloolefins written by Christopher Bryan and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Palladium Catalyzed Oxidative Cascade Cyclizations Via C N C C Formation for Synthesis of Nitrogen Heterocycles written by Wei Du and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Palladium-catalyzed oxidative cascade cyclizations via C-N/C-C formation for synthesis of nitrogen heterocycles" by Wei, Du, 杜玮, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled PALLADIUM-CATALYZED OXIDATIVE CASCADE CYCLIZATIONS VIA C-N/C-C FORMATION FOR SYNTHESIS OF NITROGEN HETEROCYCLES submitted by Du Wei for the Degree of Doctor of Philosophy at The University of Hong Kong in May 2014 Pd(II)-catalyzed oxidative amination of alkenes is a versatile method to construct N-containing heterocycles which are found in many biologically active synthetic targets, including natural products and pharmaceuticals. Considering the efficiency of the cascade reaction, we have employed this protocol to synthesize nitrogen heterocycles (including chiral ones) via Pd(II)-catalyzed C-N/C-C bond formation. We have developed a highly efficient enantioselective method for oxidative cascade cyclization of acrylamides tethered alkene using Pd(TFA) /diPh-pyrox as catalyst under a mild aerobic condition (Scheme 1). A series of pyrrolizidine derivatives, such as 2.4a, 2.2h, and 2.2n, have been synthesized in good yields and excellent enantioselectivity. The mechanism study has indicated that the cyclization reaction proceeded through both trans-/cis-aminopalladation (AP) with a ratio of ca. 3:1 (Scheme 2). Besides, we have found that some factors, including the counterions of Pd(II) complexes, the electronic density of the isolated double bond and the steric bulkiness of ligands, affect the stereochemical selectivity in the aminopalladation step. This study has important implications for designing new catalyst systems for enantioselective Pd-catalyzed oxidative amination reactions. We have also disclosed the first enantioselective Pd(II)-catalyzed oxidative aminoarylation reaction (Scheme 3). The reactions were carried out with Pd(OAc) /β-ICD as catalyst to synthesize indoline derivatives, such as 3.2a, 3.2b and 3.2i, in moderate to good yields with moderate enantioselectivity. Base on previous successful cascade reactions of aminopalladation/C(sp )-H functionalization, we have developed a palladium (II)-catalyzed oxidative cascade aminoalkylation via aminopalladation/C(sp )-H activation for divergent synthesis of three-membered-ring (i.e. 4.2ag, 4.2an and 4.2ar) or five-membered-ring (i.e. 4.3aa, 4.3ad and 4.3bs) fused indolines (Scheme 4). The benzylic C-H and the C-H at -position of anilides can be selectively activated under different reaction conditions. 3 This is the first example of palladium catalyzed C(sp )-H activation without employment of prefunctionalized reagents (halogenated or boron-containing reagents) and directing groups, representing a green and economic protocol for construction of N-containing heterocycles. Scheme 1 Scheme 2 Scheme 3 Scheme 4 DOI: 10.5353/th_b5312312 Subjects: Heterocyclic compounds - Synthesis Organopalladium compounds