The Cope Rearrangement - a Reaction with a Manifold Mechanism?

For the Cope rearrangement of hexa-1,5-dienes (cf. 1) to isomeric forms (cf. 1'), more mechanisms are at one’s disposal than was hitherto accepted. Depending on the choise of the structure, the kind of substituents of the Cope system or on the reaction conditions, most of the thinkable mechani...

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Main Authors: Rudolf Wehrli, Daniel Belluš, Hans-Jürgen Hansen, Hans Schmid
Format: Article
Language:deu
Published: Swiss Chemical Society 1976-09-01
Series:CHIMIA
Online Access:https://www.chimia.ch/chimia/article/view/9321
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author Rudolf Wehrli
Daniel Belluš
Hans-Jürgen Hansen
Hans Schmid
author_facet Rudolf Wehrli
Daniel Belluš
Hans-Jürgen Hansen
Hans Schmid
author_sort Rudolf Wehrli
collection DOAJ
description For the Cope rearrangement of hexa-1,5-dienes (cf. 1) to isomeric forms (cf. 1'), more mechanisms are at one’s disposal than was hitherto accepted. Depending on the choise of the structure, the kind of substituents of the Cope system or on the reaction conditions, most of the thinkable mechanisms can be defined. Twostep Cope processes are characterized by dissociation and recombination or by the intervention of diradicals or zwitterions as intermediates. Concerted processes can occur via the “classical” pericyclic (aromatic) or via a diradicaloid transition state. Whereas the unsubstituted hexa-1,5-diene and its derivatives with conjugative substituents in positions 1,3,4 or 6 follow the pericyclic route, systems with radical stabilizing substituents in positions 2,5 prefer to react via the diradicaloid pathway. Thus, hexa-1,5-dienes represent, from a mechanistical standpoint, quite ductile systems.
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spelling doaj-art-9f4d3fa6263f4bf39d866d67849720822025-08-20T01:47:42ZdeuSwiss Chemical SocietyCHIMIA0009-42932673-24241976-09-0130910.2533/chimia.1976.416The Cope Rearrangement - a Reaction with a Manifold Mechanism?Rudolf Wehrli0Daniel Belluš1Hans-Jürgen Hansen2Hans Schmid3Organisch-chemisches Institut der Universität Zürich, Rämistrasse 76, CH-8001 ZürichZentrale Forschungslaboratorien, Ciba- Geigy AG, CH-4002 BaselInstitut de chimie organique de l’Université de Fribourg, Pérolles, CH-1700 FribourgOrganisch-chemisches Institut der Universität Zürich, Rämistrasse 76, CH-8001 Zürich For the Cope rearrangement of hexa-1,5-dienes (cf. 1) to isomeric forms (cf. 1'), more mechanisms are at one’s disposal than was hitherto accepted. Depending on the choise of the structure, the kind of substituents of the Cope system or on the reaction conditions, most of the thinkable mechanisms can be defined. Twostep Cope processes are characterized by dissociation and recombination or by the intervention of diradicals or zwitterions as intermediates. Concerted processes can occur via the “classical” pericyclic (aromatic) or via a diradicaloid transition state. Whereas the unsubstituted hexa-1,5-diene and its derivatives with conjugative substituents in positions 1,3,4 or 6 follow the pericyclic route, systems with radical stabilizing substituents in positions 2,5 prefer to react via the diradicaloid pathway. Thus, hexa-1,5-dienes represent, from a mechanistical standpoint, quite ductile systems. https://www.chimia.ch/chimia/article/view/9321
spellingShingle Rudolf Wehrli
Daniel Belluš
Hans-Jürgen Hansen
Hans Schmid
The Cope Rearrangement - a Reaction with a Manifold Mechanism?
CHIMIA
title The Cope Rearrangement - a Reaction with a Manifold Mechanism?
title_full The Cope Rearrangement - a Reaction with a Manifold Mechanism?
title_fullStr The Cope Rearrangement - a Reaction with a Manifold Mechanism?
title_full_unstemmed The Cope Rearrangement - a Reaction with a Manifold Mechanism?
title_short The Cope Rearrangement - a Reaction with a Manifold Mechanism?
title_sort cope rearrangement a reaction with a manifold mechanism
url https://www.chimia.ch/chimia/article/view/9321
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