Chapter 17.7, Problem 18CC

Interpretation Introduction

Interpretation:

The given dienes should be ranked in terms of their reactivity (least to most) for Diels-Alder reaction.

Concept introduction:

• Diels-Alder reaction is a $\left[\text{4+2}\right]\text{ cycloaddition}$ reaction, in which a π-system having four atoms (diene) and a π-system having two atoms (dienophile) are undergoing in cycloaddition reaction and producing a substituted cyclohexene.
• Only the diene having s-cis conformation will undergo Diels-Alder reaction with dienophile.
• The dienes shows conformations due to free rotation of $\text{C}-\text{C}$ bond. The conformations are s-cis and s-trans.

Example, the conformations for 1,3-butadiene are,

To rank: the given dienes in terms of reactivity (least to most) for Diels-Alder reaction.