Claisen Rearrangement

The aliphatic Claisen Rearrangement is a [3,3]-sigmatropic rearrangement in which an allyl vinyl ether is converted thermally to an unsaturated carbonyl compound.

The aromatic Claisen Rearrangement is accompanied by a rearomatization:

The etherification of alcohols or phenols and their subsequent Claisen Rearrangement under thermal conditions makes possible an extension of the carbon chain of the molecule.

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Mechanism of the Claisen Rearrangement

The Claisen Rearrangement may be viewed as the oxa-variant of the Cope Rearrangement:

 Mechanism of the Cope Rearrangement

Mechanism of the Claisen Rearrangement

The reaction proceeds preferably via a chair transition state. Chiral, enantiomerically enriched starting materials give products of high optical purity.

A boat transition state is also possible, and can lead to side products:

The aromatic Claisen Rearrangement is followed by a rearomatization:

When the ortho-position is substituted, rearomatization cannot take place. The allyl group must first undergo a Cope Rearrangement to the para-position before tautomerization is possible.

All Claisen Rearrangement reactions described to date require temperatures of > 100 °C if uncatalyzed. The observation that electron withdrawing groups at C-1 of the vinyl moiety exert a positive influence on the reaction rate and the yield has led to the development of the following variations:

Ireland-Claisen Rearrangement

Eschenmoser-Claisen Rearrangement

Johnson-Claisen Rearrangement

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Recent Literature

Using Geminal Dicationic Ionic Liquids as Solvents for High-Temperature Organic Reactions
X. Han, D. W. Armstrong, Org. Lett., 2005, 7, 4205-4208.

Stereoselective Olefin Isomerization Leading to Asymmetric Quaternary Carbon Construction
K. Wang, C. J. Bungard, S. G. Nelson, Org. Lett., 2007, 9, 2325-2328.

Tandem Pd(II)-Catalyzed Vinyl Ether Exchange-Claisen Rearrangement as a Facile Approach to γ,δ-Unsaturated Aldehydes
X. Wei, J. C. Lorenz, S. Kapadia, A. Saha, N. Haddad, C. A. Busacca, C. H. Senanayake, J. Org. Chem., 2007, 72, 4250-4253.

A Domino Copper-Catalyzed C-O Coupling-Claisen Rearrangement Process
G. Nordmann, S. L. Buchwald, J. Am. Chem. Soc., 2003, 125, 4978-4979.

Tandem Horner-Wadsworth-Emmons Olefination/Claisen Rearrangement/Hydrolysis Sequence: Remarkable Acceleration in Water with Microwave Irradiation
E. Quesada, R. J. K. Taylor, Synthesis, 2005, 3193-3195.

Asymmetric Claisen Rearrangements Enabled by Catalytic Asymmetric Di(allyl) Ether Synthesis
S. G. Nelson, K. Wang, J. Am. Chem. Soc., 2006, 128, 4232-4233.

Gold(I)-Catalyzed Propargyl Claisen Rearrangement
B. D. Sherry, F. D. Toste, J. Am. Chem. Soc., 2004, 126, 15978-15979.

Gold(I)-Catalyzed Synthesis of Highly Substituted Furans
M. H. Suhre, M. Reif, S. F. Kirsch, Org. Lett., 2005, 7, 3873-3876.