Question

Question: What product is formed from the Cope or oxy-Cope rearrangement of each starting material?

Short answer

Answer

a.

b.

c.

Step-by-step solution

Sigmatropic rearrangement reaction

Sigmatropic rearrangement reactions are reactions where the sigma bond is cleaved in the reactant. The pi bonds undergo rearrangement to generate new sigma bonds in the product.

Cope rearrangement and oxy Cope rearrangement

The reactant, as well as the product, includes isomeric 1,5-dienes in the case of cope rearrangement. The oxy-cope rearrangement makes use of an unsaturated alcohol.

Step 3: Identifying the product formed from the Cope or oxy-Cope rearrangement

a. The given compound gets subjected to [3,3] sigmatropic rearrangement leading to the formation of (E)-methyl 4-methylhepta-2,6-dienoate. The reaction can be given as:

Sigmatropic rearrangement of compound a

b. Compound b undergoes [3,3] sigmatropic rearrangement leading to the formation of cyclopia-1,4-diene. The reaction can be given as:

Sigmatropic rearrangement of compound b

c. Compound c undergoes oxy Cope rearrangement to form (E)-cyclonic-5-enone. The reaction can be given as:

Sigmatropic rearrangement of compound c