16.25 : [3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
From a molecular orbital perspective, the rearrangement can be viewed as the interaction between the ground state frontier orbitals of the allyl anion and cation. Under thermal conditions, the two π components overlap via a symmetry-allowed suprafacial pathway.
From Chapter 16:
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16.25 : [3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.1 : Structure of Conjugated Dienes
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.2 : Stability of Conjugated Dienes
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.3 : π Molecular Orbitals of 1,3-Butadiene
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.4 : π Molecular Orbitals of the Allyl Cation and Anion
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.5 : π Molecular Orbitals of the Allyl Radical
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.6 : Electrophilic 1,2- and 1,4-Addition of HX to 1,3-Butadiene
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.7 : Electrophilic 1,2- and 1,4-Addition of X<sub>2</sub> to 1,3-Butadiene
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.8 : Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.9 : UV–Vis Spectroscopy of Conjugated Systems
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.10 : UV–Vis Spectroscopy: Woodward–Fieser Rules
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.11 : Pericyclic Reactions: Introduction
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.12 : Thermal and Photochemical Electrocyclic Reactions: Overview
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.13 : Thermal Electrocyclic Reactions: Stereochemistry
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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16.14 : Photochemical Electrocyclic Reactions: Stereochemistry
Dienes, Conjugated Pi Systems, and Pericyclic Reactions
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