Question

What diene and what dienophile should be used to synthesize the following?

Short answer

The diene and dienophile for all of the reactions are,

Step-by-step solution

Definition of Diels-Alder reaction

Diels Alder reaction is a pericyclic reaction where a diene and dienophile reacts to form a cyclic entity. This reaction is a reversible reaction. At high temperature, the cyclic compound breaks to get back the reactants,

Retro synthetic approach to Diels-Alder reaction

1. The double bond should be located in the product. The diene that was used to form the cyclic product had double bonds on either side of the existing double bond, so, that double bonds should be drawn removing the original double bond.

2. The new σ bonds are now on the other side of these double bonds. Deleting these σ bonds and putting a π bond between the two carbons whose σ bonds were deleted gives the needed reactants—that is, the diene and the dienophile.

Reaction mechanism of the given products