Chapter 14.SE, Problem 39AP

Interpretation Introduction

Interpretation:

The observation that 1, 3-pentadiene is much more reactive than 2, 4-pentanedienal in Diels-Alder reaction is to be explained.

Concept introduction:

In Diels-Alder reaction, a dienophile reacts with a diene to yield a cyclic adduct. The reaction takes place through 1, 4 addition of the dienophile into the diene through a cyclic transition state. These reactions occur rapidly with dienophiles having electron withdrawing substituent groups in conjugation with the double bond and if the diene adapts s-cis conformation during the reaction.

To explain:

The observation that 1, 3-pentadiene is much more reactive than 2, 4-pentanedienal in Diels-Alder reaction.