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Intramolecular reaction

About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.


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Journal ArticleDOI
TL;DR: The ISMS condensation of allylsilane 4 does not follow the expected pathway but rather leads to an efficient synthesis of trisubstituted and tetrasubstitized tetrahydropyran derivatives as discussed by the authors.

47 citations

Journal ArticleDOI
TL;DR: Experimental evidence supports the hypothesis that iso-30 is the more thermodynamically stable of the two regioisomers of sordaricin, and the intervention of a cycloreversion/cycloaddition pathway at elevated temperatures leading to the formation ofiso-30.
Abstract: An enantioconvergent total synthesis of sordaricin (3), the diterpene aglycon of an important class of antifungal compounds, is described. Two approaches were explored, the first of which utilized a possible biogenetic intramolecular [4 + 2] cycloaddition to form the complete carbon skeleton of the target molecule as a single regioisomer 30. A second approach employed a tandem cycloreversion/intramolecular [4 + 2] cycloaddition process to afford not only the desired product 30 but also significant quantities of the undesired regioisomer iso-30. An investigation into the reasons for the difference in regioselectivity between these two reactions revealed the intervention of a cycloreversion/cycloaddition pathway at elevated temperatures leading to the formation of iso-30. Experimental evidence supports the hypothesis that iso-30 is the more thermodynamically stable of the two regioisomers.

47 citations

Reference EntryDOI
Pat N. Confalone1, Edward M. Huie1
TL;DR: In this paper, the authors provide a thorough understanding of the nitrone-olefin cycloaddition reaction and illustrate its power by describing some significant applications to complex synthetic problems.
Abstract: Early researchers studying the condensation product of carbonyl compounds with N-substituted hydroxylamines elected to coin the term “nitrone” as a combination of the words “nitrogen” and “ketone.” This was done to emphasize the parallel between this newly discovered functionality and the already rich chemistry of the carbonyl group. For example, nitrones are capable of reacting with carbanions of various types, a consequence of the iminium species embedded in the nitrone that renders the functionality susceptible to nucleophilic attack. Thus C-phenyl-N-methylnitrone undergoes a Reformatsky reaction with ethyl bromoacetate in complete analogy with benzaldehyde. The intermediate zinc alkoxide cyclizes to 2-methyl-3-phenylisoxazolidin-5-one, a type of compound that can also be prepared by the related nucleophilic addition of dialkyl malonates to nitrones. This chapter deals with a unique property of nitrones not shared by the corresponding carbonyl compounds, namely, a marked ability to undergo a [3 + 2] cycloaddition reaction in the presence of a dipolarophile. The reactions of nitrones with substituted olefins, both intermolecular and intramolecular are addressed. This process yields isoxazolidines directly, affording products related to those obtained in the Reformatsky reaction but arising by a different reaction mode. The intent of the review presented in this chapter is to provide a thorough understanding of the nitrone–olefin [3 + 2] cycloaddition reaction and to illustrate its power by describing some significant applications to complex synthetic problems. Various aspects have been reviewed. This documentation of the nitrone–olefin cycloaddition reaction begins with the preparation and stability of the nitrone component and is followed by mechanistic considerations. A presentation of the dipolarophile syntheses is beyond the scope of this chapter; however, the tabular survey provides leading references to specific examples. The important concepts of regio- and stereo-selectivities are introduced next. Since the general rules of regiochemistry that apply in the intermolecular version of the reaction are often reversed in the intramolecular version, the latter are dealt with separately. Finally, important applications to the total synthesis of natural products are presented. The versatile utility of the nitrone–olefin cycloaddition reaction in the synthesis of natural products has been the major driving force in the development of this long-neglected chemistry. An in-depth understanding of the key transformations of the isoxazolidines afforded by the reaction will place this chemistry firmly within the arsenal of organic reactions. Keywords: cycloaddition reactions; [3 + 2] reaction; nitrone; olefins; nitrone stability; mechanism; regioselectivity; intermolecular reaction; intramolecular reaction; C-alkenylnitrones; N-alkenylnitrones; natural products; alkaloids; biotin; aldehyde-derived nitrones; ketone-derived nitrones; endocyclic nitrones; exocyclic nitrones; amino glycosides; adaline; nitrogen-free systems; experimental procedures

47 citations

Journal ArticleDOI
TL;DR: In this paper, the insertion ene d'un thioaldehyde MeO 2 CCH=S avec le β-pinene permet d'obtenir le pinene-2yl-10thio acetate de methyle.
Abstract: Une insertion ene d'un thioaldehyde MeO 2 CCH=S avec le β-pinene permet d'obtenir le pinene-2yl-10thio acetate de methyle. D'autre part, on prepare a partir du chloro-4 acetyl-acetate d'ethyle et de mercapto-2 acetophenone le meme compose qui par reaction comparable avec le cyclopentadiene fournit le dimethyl-2,4 [oxo-2' thioformyl-2' ethyl]-2pentene-4oate d'ethyle. Un piegeage interne selon Diels-Alder permet d'obtenir des heterocycles bicycliques soufres ou des sulfures monocycliques

47 citations

Journal ArticleDOI
TL;DR: In this article, an intramolecular cyclisation of methylene cyclopropanes with acetylenic acceptors affords highly functionalised bicyclonononane derivatives.

47 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231
20228
20216
202011
20199
20186