CALISEN REARRANGEMENT

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

Recent Literature

Using Geminal Dicationic Ionic Liquids as Solvents for High-Temperature Organic Reactions

Base-Mediated Cascade Rearrangements of Aryl-Substituted Diallyl Ethers

Base-Mediated Cascade Rearrangements of Aryl-Substituted Diallyl Ethers

Stereoselective Olefin Isomerization Leading to Asymmetric Quaternary Carbon Construction

Tandem Pd(II)-Catalyzed Vinyl Ether Exchange-Claisen Rearrangement as a Facile Approach to γ,δ-Unsaturated Aldehydes

A Domino Copper-Catalyzed C-O Coupling-Claisen Rearrangement Process

Tandem Horner-Wadsworth-Emmons Olefination/Claisen Rearrangement/Hydrolysis Sequence: Remarkable Acceleration in Water with Microwave Irradiation

Asymmetric Claisen Rearrangements Enabled by Catalytic Asymmetric Di(allyl) Ether Synthesis

A Convenient Triisobutylaluminium (TIBAL)-Promoted Johnson-Claisen Approach to γ,δ-Unsaturated Alcohols

Gold(I)-Catalyzed Propargyl Claisen Rearrangement

Stereocontrolled Synthesis of (E,Z)-Dienals via Tandem Rh(I)-Catalyzed Rearrangement of Propargyl Vinyl Ethers

Synthesis of Pyrroles by Gold(I)-Catalyzed Amino-Claisen Rearrangement of N-Propargyl Enaminone Derivatives

Gold(I)-Catalyzed Synthesis of Highly Substituted Furans