Question: What product is formed from the Claisen rearrangement of each starting material?

Sigmatropic rearrangement comes under the category of pericyclic reaction. The pi bonds present in the reactant as well as the product is constant in the case of sigmatropic rearrangement.

Claisen rearrangement comes under the class of [3,3] sigmatropic rearrangement. In this rearrangement reaction, an allyl vinyl ether or allyl aryl ether gets subjected to [3,3] sigmatropic rearrangement.

a. The starting material which is allyl vinyl ether gets subjected to [3,3] sigmatropic rearrangement to form 2-(cyclohex-2-enyl)acetaldehyde. The reaction can be given as:

Product formed by the Claisen rearrangement of compound a

b. The given starting material undergoes [3,3] sigmatropic rearrangement to form 1-allyl cyclohexanecarbaldehyde. The reaction can be given as:

Product formed by the Claisen rearrangement of compound b

c. The given starting material undergoes [3,3] sigmatropic rearrangement to form 2-(1-vinylcyclohexyl)acetaldehyde. The reaction can be given as:

Product formed by the Claisen rearrangement of compound c