Inter- and Intramolecular Ring-Opening Reactions of Oxabicyclic Substrates PDF Download
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Author: Christopher Wicks
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Oxabenzonorbornadiene (OBD) and derivatives thereof have become key substrates of interest within synthetic organic chemistry and natural product synthesis as they enable the formation of multiple stereocenters in a single transformation. The present work expands on previous studies to investigate various intramolecular transformations, and regiochemical implications regarding ring-opening reactions of asymmetric oxabicyclic alkenes. Acid-catalyzed intramolecular ring-opening reactions of cyclopropanated oxabenzonorbornadiene (CPOBD) derivatives were investigated to afford novel medium-sized ring systems in moderate to good yields and good to excellent regioselectivity. Similarly, a Ni catalyzed intramolecular ring-opening reaction of alkyl halide tethered OBD compounds was optimized, thus generating a naphthalene derivative in excellent yields. Lastly, iridium-catalyzed ring-opening reactions of unsymmetrical C1-substituted OBD derivatives is presented using alcohols and water as nucleophiles which allows for the selective synthesis of previously inaccessible substrates.
Author: Christopher Wicks
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Oxabenzonorbornadiene (OBD) and derivatives thereof have become key substrates of interest within synthetic organic chemistry and natural product synthesis as they enable the formation of multiple stereocenters in a single transformation. The present work expands on previous studies to investigate various intramolecular transformations, and regiochemical implications regarding ring-opening reactions of asymmetric oxabicyclic alkenes. Acid-catalyzed intramolecular ring-opening reactions of cyclopropanated oxabenzonorbornadiene (CPOBD) derivatives were investigated to afford novel medium-sized ring systems in moderate to good yields and good to excellent regioselectivity. Similarly, a Ni catalyzed intramolecular ring-opening reaction of alkyl halide tethered OBD compounds was optimized, thus generating a naphthalene derivative in excellent yields. Lastly, iridium-catalyzed ring-opening reactions of unsymmetrical C1-substituted OBD derivatives is presented using alcohols and water as nucleophiles which allows for the selective synthesis of previously inaccessible substrates.
Author: Pauline Chiu
Publisher:
ISBN: 9780315973190
Category :
Languages : en
Pages : 502
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Author: CHRISTOPHER. GAJDA
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Christine Le
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Atom-economical addition reactions to unsaturated carbonâ carbon bonds represent a powerful class of transformations in organic chemistry, since a great deal of molecular complexity can be generated from simple starting materials. Highly regio- and stereoselective processes have been made possible through the use of transition metal catalysts, alongside specialized ancillary ligands and in combination with rational substrate design. One area of research in the Lautens group involves the transition metal catalyzed asymmetric ring opening (ARO) of strained alkenes, which provides access to enantioenriched carbocyclic frameworks. Although a variety of coupling partners have been applied in this transformation, the use of soft carbon nucleophiles remains limited in scope. The first chapter describes a rhodium(I)-catalyzed ARO of meso-oxabicyclic alkenes using silyl enol ethers and ketene acetals. In analogy to the Mukaiyama aldol reaction, a novel silyl migration occurs, enabling an in situ protection of the chiral alcohols obtained. Developing new reactivity from Heck-type carbopalladation processes represents another research interest in the Lautens group. Oxidative addition into a carbonâ halogen bond constitutes the first step of nearly all palladium(0)-catalyzed cross-couplings. Conversely, reductive elimination from palladium(II) to yield an organohalide product represents a rare and often thermodynamically unfavoured process. The next two chapters address challenges in the synthesis of vinyl halides using palladium(0) catalysis via the intramolecular carbohalogenation and chlorocarbamoylation of alkynes. During our investigations, we discovered that the steric bulk of both the substrate and the phosphine ligand play an important role in promoting the desired reactivity. Mechanistic insight has been gained through combined experimental and computational studies, which implicate a palladium-catalyzed stereoisomerization in both of these transformations. Under certain conditions, we demonstrate that highly stereoselective trans-additions to alkynes can be achieved, which illustrates that specific substrate/catalyst combinations can override the inherent cis-selectivity in carbometallations. In the fourth chapter, a formal palladium(II)-catalyzed alkyne chlorocarbamoylation reaction is presented, which provides access to medicinally relevant methylene oxindole scaffolds. In contrast to the analogous protocol using palladium(0) catalysts, the reaction is initiated by an alkyne chloropalladation step, followed by intramolecular cross-coupling with a carbamoyl chloride. Experimental and computational studies provide insight into the mechanism of this reaction.
![Ring Opening Reactions of Oxabicyclic Compounds [microform] : Formation of Substituted Cyclohexadienes, Cyclohexenols and Cycloheptenols PDF](https://books.google.com/books/content/images/frontcover/BbL8ygAACAAJ?fife=w80-h100)
Author: Shihong Ma
Publisher: National Library of Canada = Bibliothèque nationale du Canada
ISBN: 9780612188976
Category :
Languages : en
Pages : 514
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Author: Rebecca Boutin
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Nucleophilic ring opening of oxabenzonorbornadiene (OBD) has been used in natural product synthesis as it enables precise creation of multiple stereocenters in a single step. The work presented in this thesis investigates how modifications to the OBD framework influences the regio- and stereochemistry of the products. The scope of the nickel catalyzed arylation of OBD was broadened by including C1-substituted substrates. Different 1,2-dihydronaphthol or naphthalene regioisomers could be obtained by varying the substituents' electronic properties. The latter chapters focus on the ring opening chemistry of OBD derivatives. Intramolecular ring opening of OBD was explored through the synthesis of OBDs with C1-tethered nucleophiles. Subsequent ring opening of these compounds yielded tricyclic and tetracyclic products. Finally, the scope of the palladium catalyzed Type 2 ring opening and the acid catalyzed Type 3 ring opening of the OBD derivative, cyclopropanated oxabenzonorbornadiene (CPOBD), was expanded to include substituted CPOBD substrates.
Author: Gordon Gribble
Publisher: Elsevier
ISBN: 0080539882
Category : Science
Languages : en
Pages : 485
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Book Description
This is the sixteenth annual volume of Progress in Heterocyclic Chemistry, and covers the literature published during 2003 on most of the important heterocyclic ring systems.This volume opens with two specialized reviews. The first covers 'Lamellarins: Isolation, activity and synthesis' a significant group of biologically active marine alkaloids and the second discusses 'Radical Additions to Pyridines, Quinolines and Isoquinolines'. The remaining chapters examine the recent literature on the common heterocycles in order of increasing ring size and the heteroatoms present.
Author:
Publisher: Elsevier Science
ISBN: 9780080445908
Category : Science
Languages : en
Pages : 924
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Book Description
Comprehensive Organometallic Chemistry, (COMC-III), Third Edition, 13 Volume Set is aimed at the specialist and non-specialist alike. It covers the major developments in the field in a carefully presented way with extensive cross-references. COMC-III provides a clear and comprehensive overview of developments since 1993 and attempts to predict trends in the field over the next ten years. Applications of organometallic chemistry continue to expand and this has been reflected by the significant increase in the number of volumes devoted to applications in COMC-III. Organic chemists have edited the volumes on organometallic chemistry towards organic synthesis - this is now organized by reaction type so as to be readily accessible to the organic community. Like its predecessors, COMC (1982) and COMC-II (1995), this new work is the essential reference text for any chemist or technologist who needs to use or apply organometallic compounds. Also available online via ScienceDirect (2006) - featuring extensive browsing, searching, and internal cross-referencing between articles in the work, plus dynamic linking to journal articles and abstract databases, making navigation flexible and easy. For more information, pricing options and availability visit www.info.sciencedirect.com. Presents a comprehensive overview of the major developments in the field since 1993 providing general and significant insights Highlights the expansion of applications in organometallic chemistry with a strong organic synthesis focus Provides a structured first point of entry to the key literature and background material for those planning research, teaching and writing about the area
Author: Armin Börner
Publisher:
ISBN:
Category : Asymmetric synthesis
Languages : en
Pages : 512
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Author: Guangbin Dong
Publisher: Springer
ISBN: 364255055X
Category : Science
Languages : en
Pages : 265
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Book Description
The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students
