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 Assisted Synthesis of Heterocycles written by Navjeet Kaur and published by CRC Press. This book was released on 2019-05-01 with total page 482 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 Norbornene mediated Palladium catalyzed Synthesis of Fused Aromatic Carbocycles and Heterocycles by Dino Alberico written by Dino Alberico and published by . This book was released on 2006 with total page 748 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 2 examines a sequence in which two alkyl-aryl bonds and one alkenyl/aryl bond are formed in one pot. The reaction conditions were optimized and the scope was examined. A variety of symmetrical and unsymmetrical tricyclic heterocycles were synthesized in good yields from a Heck acceptor and an aryl iodide containing two tethered alkyl bromides. This methodology was applied to the synthesis of a tricyclic mescaline analogue. We have developed a norbornene-mediated palladium-catalyzed tandem reaction for the preparation of fused aromatic carbocycles and heterocycles. Chapter 1 describes an alkylation/alkenylation sequence using aryl iodides and bromoenoates. The effect of substitution on the bromoenoate was evaluated. A wide variety of carbon-, oxygen-, and nitrogen-containing functional groups are tolerated allowing for rapid access to highly functionalized aromatic carbocycles. Chapter 3 describes an alkylation/C-H functionalization sequence. In this highly efficient approach, an alkyl-aryl bond and an aryl-heteroaryl bond are created from two C-H bonds in a one-pot process. A wide range of functionalized annulated indoles were synthesized in a convergent manner in high yields.
Download or read book Palladium catalyzed Heck Reaction and Tandem Cross Coupling Reactions for Heterocycle Synthesis written by Yuanqing Fang and published by . This book was released on 2007 with total page 1130 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have obtained a tetracyclic Heck product with a formal anti-beta -hydride elimination during our post-ARO Pd-catalyzed derivatization studies of dihydronaphthalenes. We found that the yield for this Heck reaction was highly base-dependent, with DABCO being optimal. The catalyst combination of Pd2(dba)3/HP(tBu)3·BF 4 and DABCO was highly efficient for this intramolecular Heck reaction under very mild conditions. Additionally, we observed tandem double Heck reactions, which selectively functionalize two C-Br bonds intra- and intermolecularly. We further developed the concept of selective intramolecular and intermolecular cross-couplings using more general gemdihaloolefin systems, which subsequently led to the development of a variety of heterocycle forming reactions. A tandem C-N/Suzuki coupling of a gemdihalovinylaniline and organoboron reagents including aryl, heteroaryl, alkenylboronic acids (or borate esters) and alkyl boranes afforded a variety of 2-substituted indoles in good to excellent yield. This new method of indole synthesis tolerated various functional groups on all positions of the indole moiety. The orthogonal approach of the sequential copper and palladium-mediated synthesis of 1,2-diarylindoles exploited the availability of diverse organoboron reagents. This new method was successfully applied for the synthesis of three Merck KDR kinase inhibitors in very good overall yields. The Pd-catalyzed tandem couplings of gemdihalovinyl systems were further extended for the synthesis of (1) 2-carbonyl indoles via a C-N coupling, carbonylation, and Suzuki sequence, (2) 2-vinyl indoles via a C-N coupling/Heck reaction sequence, and (3) 2 alkynyl indoles via a C-N/Sonogashira coupling sequence. Furthermore, a Cu-catalyzed tandem Goldberg reaction was developed for the synthesis of imidazoindolones from amino acid-tethered gemdibromoolefins. Preliminary studies towards a modular synthesis of azaindoles from N'-Boc- N'-gemdibromovinyl pyridylamine via a sequential Suzuki/direct arylation protocol was also explored. This new tandem coupling reaction was also successfully extended to two other pharmaceutically important families of heterocycles, azaindoles and thienopyrroles. Suitable substituents (such as alkyl, Boc, and Cbz) on the amino group of the substrate were essential to prevent catalyst poisoning during the tandem process.
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 catalyzed Synthesis of Functionalized Aromatic Carbocycles and Heterocycles written by Alena Rudolph and published by . This book was released on 2009 with total page 802 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our group has expanded the synthetic utility of a palladium-catalyzed norbornene-mediated domino process first described by Catellani, to access a variety of fused aromatic heterocycles and medicinally relevant scaffolds.Chapter 1 describes a domino aromatic alkylation/Heck reaction sequence to generate tricyclic heterocycles. We significantly expanded the scope of this reaction to include a variety of heteroatoms including sulphur, nitrogen, benzylic oxygens and silicon. In particular, tricyclic analogues of mescaline, implicated in the treatment of disorders such as schizophrenia and depression, are easily accessed by this method.Chapter 2 examines the application of unactivated secondary alkyl halides as the aromatic alkylating reagent in this process. We have successfully demonstrated that secondary alkyl halides react intramolecularly and intermolecularly, and stereospecifically to afford a variety of polycyclic heterocycles. A number of termination steps have also proved to be compatible with this process, such as the Heck reaction, the direct arylation of heterocycles and a Buchwald-Hartwig amination. Notably, we used the structural features of these secondary alkyl halides to gain key stereochemical and mechanistic information for the overall palladium-catalyzed reaction.Chapter 3 describes a second area of research within our group that investigates the development of desymmetrizing ring-opening reactions via the addition of nucleophiles to strained meso bicyclic alkenes to afford tetrahydronaphthalene cores. Specifically the palladium-catalyzed, asymmetric ring opening of azabenzonorbornadiene with organoborons is investigated, which proceeds with moderate to good enantioselectivities depending on the nature of the boronic acid employed. Others in our group have recently demonstrated the utility of this methodology in the first asymmetric syntheses of a family of naturally occurring alkaloids, displaying a wide variety of pharmacological activities.
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 0 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 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 Synthesis of Heterocycles via Metal Catalyzed Reactions that Generate One or More Carbon Heteroatom Bonds written by John P. Wolfe and published by Springer. This book was released on 2013-09-11 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthesis of Saturated Heterocycles via Metal-Catalyzed Alkene Carboamination or Carboalkoxylation Reactions, by John P. Wolfe Synthesis of Saturated Heterocycles via Metal-Catalyzed Alkene Diamination, Aminoalkoxylation, or Dialkoxylation Reactions, by Sherry R. Chemler Synthesis of Heterocycles via Metal-Catalyzed Wacker-Type Oxidative Cyclization Reactions of Alkoxy- or Amino-Alkenes, by Wanbin Zhang Synthesis of Saturated Heterocycles via Metal-Catalyzed Hydroamination or Hydroalkoxylation Reactions, by Lisa D. Julian Synthesis of Saturated Heterocycles via Metal-Catalyzed Allylic Alkylation Reactions, by Aaron Aponick Synthesis of Heterocycles via Metal-Catalyzed Cascade/Domino Reactions that Generate a C–N or C–O Bond, by Mark Lautens Synthesis of Saturated Heterocycles via Metal-Catalyzed Formal Cycloaddition Reactions that Generate a C–N or C–O Bond, by Jerome Waser
Download or read book Palladium Catalyzed Mechanochemical Cross Coupling Reactions written by Tamae Seo and published by Springer Nature. This book was released on with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stereoselective Heterocycle Synthesis via Alkene Difunctionalization written by David A. Petrone and published by Springer. This book was released on 2018-04-02 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book investigates the use of palladium modified by bulky ligands as catalysts for new chemical transformations that rapidly assemble several classes of complex heterocyles. It documents the development of new chemical reactions involving carbon–carbon (C‒C) and carbon–halogen (C‒X) bond formation in the context of alkene difunctionalization and dearomatization reactions. Due to the ubiquity of heterocycles in bioactive natural products and life-improving pharmaceutical treatments, a long-term goal for synthetic organic chemists has been to develop novel and creative heterocycle syntheses that illicit a high degree of product diversity and are characterized by mild reaction conditions and limited waste production. A considerable fraction of leading pharmaceutical drugs contain at least one heterocycle within their chemical structure, and their prevalence in these technologies is strong evidence that the fundamental curiosities of organic chemistry lead to real-world solutions for the health and wellness of the global population.
Download or read book Palladium and Nickel Catalyzed Transformations Forming Functionalized Heterocycles written by Hyung Yoon and published by Springer Nature. This book was released on 2020-09-02 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents Pd- and Ni-catalyzed transformations generating functionalized heterocycles. Transition metal catalysis is at the forefront of synthetic organic chemistry since it offers new and powerful methods to forge carbon–carbon bonds in high atom- and step-economy. In Chapter 1, the author describes a Pd- and Ni-catalyzed cycloisomerization of aryl iodides to alkyl iodides, known as carboiodination. In the context of the Pd-catalyzed variant, the chapter explores the production of enantioenriched carboxamides through diastereoselective Pd-catalyzed carboiodination. It then discusses Ni-catalyzed reactions to generate oxindoles and an enantioselective variant employing a dual ligand system. Chapter 2 introduces readers to a Pd-catalyzed diastereoselective anion-capture cascade. It also examines diastereoselective Pd-catalyzed aryl cyanation to synthesize alkyl nitriles, a method that generates high yields of borylated chromans as a single diastereomer, and highlights its synthetic utility. Lastly, Chapter 3 presents a Pd-catalyzed domino process harnessing carbopalladation, C–H activation and π-system insertion (benzynes and alkynes) to generate spirocycles. It also describes the mechanistic studies performed on these reactions.
Download or read book Aromatic C sp2 H Dehydrogenative Coupling Reactions written by Bagher Eftekhari-Sis and published by CRC Press. This book was released on 2019 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This comprehensive text covers the research and development trends in the growing field of aromatic C-H dehydrogenative coupling reactions, leading to different types of heyterocycles. The author provides answers to how this coupling reaction occurs, what kinds of heterocycles are synthesized, and what its advantages are. The palladium, rhodium, iridium, copper, cobalt, ruthenium and ferric catalyzed aromatic C(sp2)-H dehydrogenative cross-coupling reactions are described in detail. A useful reference source for researchers and graduates in the field of heterocyclic chemistry and transition metal catalyzed dehydrogenative coupling reactions"--
Download or read book Organic Synthesis with Palladium Compounds written by Jiro Tsuji and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 221 pages. Available in PDF, EPUB and Kindle. Book excerpt: Around 30 years ago the transition metal chemistry received great impulses. In the focus have been reactions of nickel and cobalt and herein especially their carbonyls. Also industrial processes have been developed. When the technical oxidation of ethylene with palladium chloride had been discovered, and a great number oflaboratory reactions, many groups have turned towards this subject. Apart from two important industrial processes - acetaldehyde and vinylacetate from ethylene - a great number of conversions and catalytic reactions with palladium compounds have been researched. Their mechanisms have been cleared up and have con tributed to a better understanding of the complex chemistry of palladium. Last but not least these reactions have also served for more understanding of organic transition metal compounds and catalyses in general. Numerous conventional reactions appear today in a different light. The effects of co-
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 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.
