Chapter 14.SE, Problem 38AP

Interpretation Introduction

Interpretation:

The observation that 1, 3-cyclopentadiene is very reactive in Diels-Alder reaction, but 1, 3-cyclohexadiene is less reactive and 1, 3-cycloheptadiene is inert 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 1, 3-cyclopentadiene is very reactive in Diels-Alder reaction, but 1, 3-cyclohexadiene is less reactive and 1, 3-cycloheptadiene is inert.