Chapter 13, Problem 38P

Interpretation Introduction

Interpretation:

The reason why the given molecule, being a conjugated diene, cannot undergo the Diels–Alder reaction is to be explained.

Concept introduction:

舧 Diels–Alder is a type of organic reaction in which substituted alkene and conjugated diene react to form substituted cyclohexene derivative. It is a single step reaction.

舧 The general reaction of Diels–Alder is as follows:

舧 The Diels–Alder reaction is between a conjugate diene and a reactant containing double bond (dienophile) to form a product, which is called adduct.

舧 The Diels–Alder reactions are highly stereospecific. The configuration of dienophile is retained in the product and the reaction is the syn addition.

舧 The dienes react with dienophiles in cis form rather than trans form.

舧 Endo and exo refers to the orientation of dienophile and its electron withdrawing group, when it reacts with a diene in Diels Alder reaction.

舧 The reaction with orientation of electron-withdrawing group of dienophiles under the $\pi$ orbitals of the diene, is Endo.

舧 The reaction with orientation of electron-withdrawing group of dienophiles away from the $\pi$ orbitals of the diene, is Exo

舧 Endo is favored in the transition state of Diels Alder reaction because of its lower energy.

舧 If a compound is stable, it has lower energy and if a compound is unstable, it has higher energy.