Chapter 14.SE, Problem 34AP

Interpretation Introduction

Interpretation:

The observation that cis-1,3-pentadiene is much less reactive than trans-1,3 pentadiene 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 a s-cis conformation during the reaction.

To explain:

The observation that cis-1,3-pentadiene is much less reactive than trans-1,3 pentadiene in Diels-Alder reaction.