[PDF] Net 3 2 Type Heterocyclic Synthesis Via Organostannanes And Palladium Chemistry eBook

Author : Navjeet Kaur
Publisher : CRC Press
Page : 432 pages
File Size : 26,99 MB
Release : 2019-05-01
Category : Medical
ISBN : 1351242601

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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.

Author : Hyung Yoon
Publisher : Springer Nature
Page : 236 pages
File Size : 33,81 MB
Release : 2020-09-02
Category : Science
ISBN : 3030540774

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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.

Author : Yusuke Ohta
Publisher : Springer Science & Business Media
Page : 110 pages
File Size : 37,36 MB
Release : 2011-01-20
Category : Science
ISBN : 3642154735

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A copper-catalyzed direct synthesis of 2-(aminomethyl)indoles by catalytic domino reaction including multi-component coupling was developed, and is the first example of a three-component indole formation without producing salts as a byproduct. Based on this reaction, a copper-catalyzed synthesis of 3-(aminomethyl)isoquinoline was accomplished which represents an unprecedented isoquinoline synthesis through a four-component coupling reaction. Following these results, extensive application studies using one-pot palladium-, acid-, or base-promoted cyclization revealed that indole- or isoquinoline-fused polycyclic compounds can be readily synthesized through multi-component reactions. As the concept of Green Chemistry becomes ever more important, these findings may provide efficient and atom-economical approaches to the diversity-oriented synthesis of bioactive compounds containing a complex structure. This could lead to development of promising drug leads with structural complexity. The work of this thesis will go on to inspire the synthetic research of many readers.

Author : Wei Du
Publisher :
Page : pages
File Size : 47,44 MB
Release : 2017-01-27
Category :
ISBN : 9781361385456

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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

Author : Dawei Yue
Publisher :
Page : 452 pages
File Size : 45,15 MB
Release : 2004
Category :
ISBN :

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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.

Author :
Publisher :
Page : pages
File Size : 35,31 MB
Release : 2016
Category : Heterocyclic chemistry
ISBN : 9781783269242

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"Heterocyclic chemistry constitutes the largest branch of chemistry, covering almost two-thirds of literature in the field. In addition, around 90% of naturally-occurring molecules have heterocycles as their core structure. Therefore, as a central part of organic chemistry, the discovery of new methodologies in synthesizing heterocyclic compounds is essential to their continued application and development. Transition metal catalysts offer a low cost and often low toxicity pathway for heterocycles synthesis, while the use of noble metals represents an alternative form of experimentation which is discussed in the book. Noble Metals, Noble Value provides the first comprehensive analysis of the applications of the noble metals of ruthenium (Ru), rhodium (Rh) and palladium (Pd) catalysts in heterocycles synthesis. Pairs of chapters are dedicated to summarizing each of the metals when applied to either five- or six-membered heterocyclic syntheses. An introduction to the importance of heterocycles and possible procedures for the preparation of heterocyclic compounds is also given. With up to date research and findings, this review is excellently suited to academics and professionals in the field of chemistry, with a particular focus on the specialities of biological, catalytic and organic chemistry."--

Author : Charles Hamilton Heath
Publisher :
Page : 316 pages
File Size : 22,7 MB
Release : 2011
Category : Heterocyclic compounds
ISBN :

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This thesis describes our synthetic endeavours in nitrogen containing heterocyclic compounds. The work included several key themes including the pursuit of biologically active compounds, the development of elegant and environmentally benign procedures including domino reactions. The use of palladium mediated transformations in organic synthesis, the construction of new unknown ring systems and the structural elucidation of heterocyclic compounds including the structural elucidation of natural products by synthesis have also been explored. Chapter 2 describes our synthetic investigations of the 3-benzazepines I and azepino[4,5-b]indoles II. Through the use of the palladium catalysed Tsuji-Trost reaction followed by a Heck reaction we were able to devise a synthetic approach to access these N-heterocycles. We were able to synthesize simple derivatives of both I and II in addition to more complex compounds featuring additional fused rings by including the use of different cyclic and acyclic allylic substrates for the Tsuji-Trost reaction. After the development of the single step Tsuji-Trost/Heck synthetic protocols for these compounds we successfully combined these two reactions into a single pot domino reaction. In addition to Tsuji-Trost/Heck domino reactions we have also developed a Heck/carbopalladation domino reaction for the synthesis of an azepino[3,4,5-hi]benz[b]indolizine derivative. Chapter 3 describes our attempts to synthesize the natural product arboflorine. We initially began with attempts to elaborate the azepino[4,5-b]indoles synthesized in Chapter 2 to provide arboflorine, however this did not prove fruitful. In the course of this investigation we discovered a novel rearrangement of an azepino[4,5-b]indole to give the peroxide IV which became the topic of Chapter 4. We attempted to further elaborate other known azepino[4,5-b]indoles via a variety of methods including inter and intramolecular Heck reactions, radical chain reactions and functionalization via an iminium salt. These attempts were also unsuccessful. Finally we chose to modify the synthesis of a simpler, related tetracycle for the synthesis of arboflorine, developed by Bosch and Passarella. Following their general synthetic strategy we were able to synthesize a key nitrile intermediate to the synthesis of arboflorine. The cyclization of this nitrile was attempted but was not successful under a series of reaction conditions. Chapter 4 describes the structural elucidation of the peroxide IV. A possible mechanistic explanation for the formation of the peroxide is given and this is discussed in the context of relevant literature examples. The formation of the peroxide IV led to our increased interest in the general reactivity of the azepino[4,5-b]indoles and several simple reactions were carried out in the hope of discovering further novel rearrangements.

Author : Dmitry Valerievich Kadnikov
Publisher :
Page : 702 pages
File Size : 17,92 MB
Release : 2002
Category :
ISBN :

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The subject of this dissertation is the study of palladium-catalyzed reactions of internal and terminal alkynes with ortho-substituted aryl iodides such as, o-iodophenols and N-substituted o-iodoanilines, in the presence of carbon monoxide (carbonylative annulation). The exploration of these reactions have led to the development of efficient syntheses of the important heterocycles coumarins and 2-quinolones. 3,4-Disubstituted coumarins are efficiently synthesized by the palladium-catalyzed annulation of internal alkynes by o-iodophenols in the presence of just one atmosphere of carbon monoxide. The use of a sterically unhindered pyridine base is essential to achieve high yields. The reaction accommodates a number of organic functional groups both on the alkyne and the o-iodophenol, thus affording a wide variety of coumarins in moderate to good yields. The main disadvantage of the process is formation of mixtures of regioisomers in reactions employing unsymmetrical alkynes. The use of N-substituted o-iodoanilines as annulating agents provides an efficient synthesis of 3,4-disubstituted 2-quinolones. In this process, the selection of the nitrogen protecting group is crucial for the success of the reaction. The best results are obtained utilizing alkyl carbamates, tosylamides and trifluoroacetamides. The major features of this process are similar to those of the coumarin synthesis. These annulation processes are the first examples of the insertion of an alkyne into the arylpalladium bond occurring in preference to the insertion of CO. We have shown that the unusual order of insertion arises from the low reactivity of the initially formed acylpalladium complex towards internal alkynes. Utilizing the reaction conditions developed for the carbonylative annulation of internal alkynes we have been able to affect the carbonylative annulation of terminal alkynes by o-iodophenols or o-iodoaniline derivatives to afford coumarins or 2-quinolones, respectively, in modest yields. The formation of coumarins and 2-quinolones in this process is in stark contrast with all previously described palladium-catalyzed carbonylative annulation of terminal alkynes, which have afforded chromones and 4-quinolones. Moreover, under our reaction conditions terminal alkynes insert into the carbon-palladium bond instead of undergoing a Sonogashira-type coupling. This reaction pathway is confirmed by an isotope labeling experiment.