Question

A $\mathrm{\beta },\mathrm{\gamma }$-unsaturated carbonyl compound rearranges to a more stable conjugated $\mathrm{\alpha },\mathrm{\beta }$-unsaturated compound in the presence of either acid or base.

a. Propose a mechanism for the base- catalyzed rearrangement.

b. Propose a mechanism for the acid- catalyzed rearrangement.

$\mathrm{\beta },\mathrm{\gamma }$-unsaturated carbonyl compound $\mathrm{\alpha },\mathrm{\beta }$-unsaturated carbonyl compound

Short answer

The answer is,

a.

Mechanism

b.

Mechanism

Step-by-step solution

Step-by-Step Solution Step 1: Rearrangement reactions

The rearrangement reactions are the reactions involving the rearrangement of atoms or groups. They can be acid catalyzed or base catalyzed rearrangement reactions.

Subpart (a)

The mechanism for the base catalyzed rearrangement is shown below.

Mechanism

Subpart (b)

The mechanism for the acid catalyzed rearrangement is shown below.

Mechanism