Chemistry
Ring Synthesis
Ring synthesis is a chemical process that involves the creation of cyclic compounds from non-cyclic precursors. This can be achieved through a variety of methods, including cyclization reactions and ring-closing metathesis. Ring synthesis is an important tool in the development of new drugs and materials.
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4 Key excerpts on "Ring Synthesis"
eBook - PDF- Michael Harmata(Author)
- 1999(Publication Date)
- JAI Press(Publisher)
In address- ing many problems at the molecular level, we are no longer con- strained to consider only what is available or what nature has produced, but now we can design what is desirable and, in many circumstances, synthesize such designed systems with practical effi- ciency. The increasing sophistication of synthesis has beneficially transformed virtually every field of science, including most notably biotechnology, medicine, and materials science. It has also enabled the emergence of fundamentally new areas of research, such as com- binatorial synthesis and nanotechnology, that will shape the practice of science in the next century. The continuing evolution of organic synthesis and its role in the broader context of science are inexorably coupled to the design, discovery, and development of new reactions and strategies that enable the preparation of high technology targets from readily available materials in a simple, safe, and practical fashion. 2 In this chapter, we place special emphasis on a new class of reactions that have great potential for addressing a range of problems in seven-membered-Ring Synthesis, including both natural and designed systems with excep- tional biological activity (Figure 1). We also illustrate how the con- ceptual basis for this process can be used to design other new reactions to synthesize a variety of ring systems and sizes. To establish the synthetic context for this new class of reactions, we provide first a classification of the four generic strategiesfor synthesizing any ring system. Using this organizational backdrop, we 9focus then on the specific problem of making seven-membered rings and initially give an overview of strategies and representative methods for addressing this problem. Subsequently we describe the design and development of a new class of cycloaddition reactionsfor seven-membered Ring Synthesis, namely, [5+2] cycloadditions of vinylcyclopropanes and
- Jie Jack Li(Author)
- 2010(Publication Date)
- Wiley(Publisher)
In such a challenging setting, any author or group of authors must be regarded as heroic if through their efforts, the task of the synthetic chemist is eased. This volume on methods for formation of carbon rings brings to the attention of practicing synthetic chemists and students of chemistry a wide array of tools for the formation of such rings by synthesis. Since cyclic structures are among the most useful molecules, it is a valuable addition to the literature that will prove its merit for years to come. The new knowledge that arises with its help will prove to be of great benefit to humankind. E. J. Corey February 1,2010 ix This page intentionally left blank Preface This book is the fifth volume of the series Comprehensive Name Reactions, an ambitious project conceived by Professor E. J. Corey of Harvard University in the summer of 2002. Volume 1, Name Reactions in Heterocyclic Chemistry, was published in 2005. Volume 2, Name Reactions for Functional Group Transformations was published in 2007. Volumes 3 and 4 on homologations were both published in 2009. They have been warmly received by the organic chemistry community. After this Volume 5, Name Reactions on Carbocyclic Ring Formations is out in 2010, we will roll out the final volume, Volume 6 on Name Reactions in Heterocyclic Chemistry—Part II, in 2011. Continuing the traditions of the first four volumes, each name reaction in Volume 5 is reviewed in seven sections: 1. Description, 2. Historical Perspective, 3. Mechanism, 4. Variations and Improvements, 5. Synthetic Utility, 6. Experimental, and 7. References. I also introduced a symbol [R] to highlight review articles, book chapters, and books dedicated to the respective name reactions. I have incurred many debts of gratitude to Professor E. J. Corey. What he once told me — "The desire to learn is the greatest gift from God" — has been a true inspiration.
eBook - PDFThe Algebra of Organic Synthesis
Green Metrics, Design Strategy, Route Selection, and Optimization
- John Andraos(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
475 10 Ring Construction Strategies Thefeatureofringsinorganicmoleculesisatopdrawtomakeamoleculeaworthytargetofsyn-thesisforsyntheticchemists�Itisherewhereachemistcandisplayhisorhergreatestingenuityand prowess�Itisalsoarguablythesinglemostimportantstructuralmotifthathasdriventhedevelop-mentofsyntheticmethodologyinorganicchemistry�Thereisadirectlinkbetweenoverallmolecular complexityandringsystemcomplexity�Themoreexotictheringsystemisthemoresyntheticchem-istsareattractedtotakeupthechallengeofcomingupwithaviablesynthesisplanforthattarget structure�Ofcourse,thegreatestarchitectofsuchringsystemsisNature�Rotecombinatorialchemi-calapproacheshavenohopeofmatchingtheexquisiteringsystemsfoundinNature�Thisiswhy naturalproductschemistryalwaysinspireschemists,drivesthediscoveryofnovelchemistrydevel-opment,andhashadthemostsuccessindeliveringleadcompoundsthatbecomefuturemedicines� As the synthetic organic chemistry literature grows exponentially and haphazardly in every direction,itisimperativethatchemistscreateintelligentdatabasesandsearchtoolstominethem forringconstructionstrategies�ThischapteralongwithAppendixA�7isthefirstattempttofocus attentiononthistask�Webeginbyintroducingasimpleuniversalcodeorgraphicalalgebraforenu-meratingtheconstructionofmonocyclicandbicyclicrings�Thisfacilitatesthecodificationofthe nebulousconceptofstrategyaswellasthesortingofstrategiesaccordingtopatterns�Thefollowing sectionssummarizetheresultsforthesynthesisdatabasedescribedinthisbook�Ultimately,such informationmaybeusedasapowerfultoolinsynthesisoptimizationsothatthe“greenest”planto anygiventargetmaybefound� Weillustratethebasicideasusingthesix-memberedmonocycleandthe[3�3�0]and[2�2�1]bicy-clicringsystemsasexamples�Theringsaredisplayedasgraphswithlinesandnodestoshowthe frameworkofconnectivity�Newbondsmadeinthetransformationareshowningrayscale�Next,
eBook - ePub- Eric F.V. Scriven(Author)
- 2013(Publication Date)
- Academic Press(Publisher)
Chapter 2 Ring SynthesisPaul A. Keller∗ , Mohammed K. Abdel-Hamid∗∗ and Ashraf M. Abdel-Megeed∗∗ ,∗ School of Chemistry, University of Wollongong, Wollongong, NSW 2522, Australia,∗∗ Department of Medicinal Chemistry, Faculty of Pharmacy, Assiut University, Assiut 71526, Egypt1 Introduction
This chapter will present the synthesis of basic pyridines functionalised in various positions with a range of different substituents. The discussion will highlight the advantages of each synthetic strategy.The synthesis of pyridines has a long history and the more traditional methods can still rank as some of the more reliable and favoured synthetic strategies. For example, condensation reactions are still commonly used methods with the advantages of being reliable and simple. More modern methods have emerged in the past decade for the synthesis of pyridines with great advances in the field of metal-catalysed reactions, including the use of palladium and copper. In particular, there has been much development in the use of alkyne chemistry, especially with the use of metal–alkene/alkyne chemistry.The synthesis of pyridines by aromatisation of the partially or fully saturated 6-membered ring containing one nitrogen atom is an important synthetic strategy and, therefore, is substantially reported here as a separate section. However, often, a key sequence of reactions towards the synthesis of pyridines involves cyclic intermediates of the same type – such strategies hold equal importance in any consideration of best methods to pyridines and hence, although there may be some duplication in these aromatisation reactions, such multistep syntheses are also reported here under the appropriate headings. There is a similar overlap in classification when considering transformations from (other) ring systems to the 6-membered pyridine moiety – when the starting material ring is <6 atoms, these could also be considered under different fragment addition-type reactions. Important examples of these types of reactions are highlighted in all appropriate sections.
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