Chapter 20, Problem 20.43P

Interpretation Introduction

Interpretation:

The structural formula for the given compound A has to be proposed along with the mechanism for the formation of the given tricyclic product.

Concept Introduction:

Diazotisation:

It is the formation of diazonium salt from the reaction between a secondary amine such as aniline and sodium nitrite in acidic medium.

Diels-Alder reaction:

It is the reaction of conjugated dienes with double or triple bonded compounds which are known as “dienophiles”. The reaction is a $4+2$ cycloaddition reaction that results in the formation of a six membered cyclic product which is known as “adduct”.

Example:

Diels-Alder reaction to form bicyclic system:

The Diels-Alder adduct formed in the Diels-Alder reaction can also be a bicyclic system which will be obtained when cylopentadiene is used as the diene as shown here:

In this reaction, the cylopentadiene acts as both diene and dienophile and formed a bicyclic system. When it is heated to ${\text{170}}^{\text{o}}\text{C}$, a reverse Diels-Alder reaction takes place in which the bicyclic system will be decomposed and gives back the cylopentadiene.