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Chapter 24: Phenols |  |
Claisen Rearrangment of Aryl Allyl Ethers
Summary
- Aryl allyl ethers undergo a thermal rearrangement to give ortho-allylphenols.
- This reaction is an intramolecular process.
- A sigmatropic rearangement is a reaction is which a σ bond migrates from one end of a π system to the other.
- Note how closely the mechanism of this reaction (table below) resembles that of the Diels-Alder reaction:
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| Step 1:
An electrocyclic process. Push those electrons around the 6 membered ring.... Best appreciated by starting the electron flow by having the aromatic C=C attacking the allyl C=C and displacing an O leaving group.... |
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| Step 2:
Tautomerisation of the ketone (actually a dienone) to the more stable aromatic enol, the phenol. |
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© Dr. Ian Hunt, Department of Chemistry |  |