Allyl Vinyl Ethers

Definition

Allyl vinyl ethers are a class of organic compounds that contain both an allyl group and a vinyl ether functional group. These compounds are of interest in the context of sigmatropic rearrangements, as they can undergo a thermal [3,3]-sigmatropic rearrangement known as the Claisen rearrangement.

5 Must Know Facts For Your Next Test

1. Allyl vinyl ethers can undergo a thermal [3,3]-sigmatropic rearrangement known as the Claisen rearrangement, which involves the migration of the allyl group to the vinyl ether carbon.
2. The Claisen rearrangement of allyl vinyl ethers is a powerful tool in organic synthesis, as it allows for the construction of more complex molecules from simpler starting materials.
3. The Claisen rearrangement of allyl vinyl ethers is typically carried out at elevated temperatures, with the reaction rate and product distribution influenced by factors such as the substituents on the allyl and vinyl ether groups.
4. The Claisen rearrangement of allyl vinyl ethers is a concerted, pericyclic reaction that proceeds through a cyclic transition state and follows the Woodward-Hoffmann rules for allowed sigmatropic rearrangements.
5. Allyl vinyl ethers can also undergo other types of sigmatropic rearrangements, such as the ene reaction, depending on the specific reaction conditions and substituents present.

Review Questions

• Explain the structural features of allyl vinyl ethers and how they relate to the Claisen rearrangement.
  • Allyl vinyl ethers are organic compounds that contain both an allyl group (-CH2CH=CH2) and a vinyl ether functional group (R-O-CH=CH2). The presence of these two reactive moieties allows allyl vinyl ethers to undergo a thermal [3,3]-sigmatropic rearrangement known as the Claisen rearrangement. In this reaction, the allyl group migrates to the vinyl ether carbon, resulting in the formation of a substituted γ,δ-unsaturated carbonyl compound. The specific structural features of the allyl and vinyl ether groups, as well as any substituents present, can influence the rate and outcome of the Claisen rearrangement.
• Describe the mechanism of the Claisen rearrangement of allyl vinyl ethers and explain how it is classified as a sigmatropic reaction.
  • The Claisen rearrangement of allyl vinyl ethers is a concerted, pericyclic reaction that proceeds through a cyclic transition state. In this [3,3]-sigmatropic rearrangement, the allyl group migrates to the vinyl ether carbon, forming a new carbon-carbon bond and resulting in the formation of a substituted γ,δ-unsaturated carbonyl compound. The Claisen rearrangement is classified as a sigmatropic reaction because it involves the migration of a σ-bond from one position in the molecule to another position, with the new bond being formed in a different location. The Woodward-Hoffmann rules for allowed sigmatropic rearrangements dictate the stereochemistry and regiochemistry of the Claisen rearrangement of allyl vinyl ethers.
• Discuss the synthetic utility of the Claisen rearrangement of allyl vinyl ethers and provide examples of how this reaction can be used to construct more complex organic molecules.
  • The Claisen rearrangement of allyl vinyl ethers is a powerful tool in organic synthesis, as it allows for the construction of more complex molecules from simpler starting materials. By leveraging the reactivity of the allyl and vinyl ether groups, the Claisen rearrangement can be used to introduce new functional groups and carbon-carbon bonds, enabling the synthesis of a wide range of organic compounds. For example, the Claisen rearrangement can be used to prepare substituted γ,δ-unsaturated carbonyl compounds, which can then be further functionalized through additional reactions. This versatility makes the Claisen rearrangement of allyl vinyl ethers a valuable synthetic transformation in the toolbox of organic chemists.

Related terms

Allyl Group: The allyl group is a functional group with the formula -CH2CH=CH2, consisting of a methylene group attached to a vinyl group.

Vinyl Ether: A vinyl ether is a type of ether where one of the alkoxy groups is a vinyl group, with the formula R-O-CH=CH2.

Claisen Rearrangement: The Claisen rearrangement is a [3,3]-sigmatropic rearrangement that converts an allyl vinyl ether into a substituted γ,δ-unsaturated carbonyl compound.