Chapter 24, Problem 24.49P

Interpretation Introduction

(a)

Interpretation:

For the given Diels-Alder reaction, two constitutional isomers can be produced. The mechanism for the formation of each isomer is to be drawn.

Concept introduction:

The $\left[\text{4+2}\right]$ cycloaddition reactions are generally known as a Diels-Alder reaction. In this reaction, a conjugated diene and a dienophile are joined via the formation of two new sigma bonds. The product is a six-membered ring. For a Diels-Alder reaction to proceed, the diene essential be able to achieve the s-cis conformation. Diels-Alder reactions cannot take place with the diene in the s-trans conformation. Diels-Alder reactions cannot take place with the diene in the s-trans conformation. Electron-donating groups attached to the diene and electron-withdrawing groups attached to the dienophile facilitates the reaction. These reactions are highly stereospecific and regioselective. Substituents that are cis to each other about the carbon-carbon double bond of the dienophile end up cis to each other in the new ring that is produced. Otherwise, the substituents end up trans to each other in the ring. Substituents attached to the terminal carbons of the diene end up cis to each other in the new ring that is produced if the double bonds of the diene are both cis or both trans. Otherwise, the substituents end up trans to each other in the ring. When the diene and dienophile are both unsymmetric, two isomeric products can be produced.

Interpretation Introduction

(b)

Interpretation:

The major product among the two possible products for the given Diels-Alder reaction is to be determined.

Concept introduction:

The $\left[\text{4+2}\right]$ cycloaddition reactions are generally known as a Diels-Alder reaction. In this reaction, a conjugated diene and a dienophile are joined via the formation of two new sigma bonds. The product is a six-membered ring. For a Diels-Alder reaction to proceed, the diene essential be able to achieve the s-cis conformation. Diels-Alder reactions cannot take place with the diene in the s-trans conformation. Diels-Alder reactions cannot take place with the diene in the s-trans conformation. Electron-donating groups attached to the diene and electron-withdrawing groups attached to the dienophile facilitates the reaction. These reactions are highly stereospecific and regioselective. Substituents that are cis to each other about the carbon-carbon double bond of the dienophile end up cis to each other in the new ring that is produced. Otherwise, the substituents end up trans to each other in the ring. Substituents attached to the terminal carbons of the diene end up cis to each other in the new ring that is produced if the double bonds of the diene are both cis or both trans. Otherwise, the substituents end up trans to each other in the ring. When the diene and dienophile are both unsymmetric, two isomeric products can be produced.