Chapter 24, Problem 24.2YT

Interpretation Introduction

Interpretation:

The curved arrows are to be supplied and the diene and dienophile are to be labeled for the reaction in Equation 24-3.

Concept introduction:

$\text{Ethene}$ reacts with $\text{buta-1, 3-diene}$, a conjugated diene, to form $\text{cyclohexene}$. This is the simplest example of what is called the Diels-Alder reaction. The Diels-Alder reaction is especially useful because it forms two new carbon-carbon bonds. Diels-Alder reactions can be carried out under mild conditions. A Diels-Alder reaction involves a diene and a dienophile. A diene contributes four π electrons from a pair of conjugated $\text{π}$ bonds. A dienophile (meaning “diene loving”) contributes two $\text{π}$ electrons from a single $\text{π}$ bond. Consequently, a Diels-Alder reaction can be described as a [4+2] cycloaddition, where the numbers indicate the number of $\text{π}$ electrons contributed by each species involved.