Chapter 20, Problem 20.47P

(a)

Interpretation Introduction

Interpretation: The mechanism for the formation of compound A has to be proposed.

Concept Introduction:

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:

This mechanism shown that three $\text{π}$-bonds are broken to form two new $\text{σ}$ -bonds and a new $\text{π}$-bond.

Formation of Benzyne:

The elimination of two halogens from the halobenzene forms the most reactive neutral intermediate with triple bond which is known as Benzyne intermediate.

Diels-Alder reaction with Benzyne intermediate:

The reaction of Benzyne with furan serves as an example for this reaction:

Benzyne is an extremely reactive species because of the presence of triple bond in it. It undergoes Diels-Alder reaction in which it acts as dienophile and reacts with furan which acts a diene. The resulted product will be a tricyclic product which is known as Diels-Alder adduct.

(b)

Interpretation Introduction

Interpretation: Using the given sources, the conversion of compound (A) into Tolciclate has to be shown.

Concept Introduction:

Acidic hydrolysis of ether:

Ether on hydrolysis gets converted into two moles of alcohols of same type in the case of symmetrical ether and of different types in the case of unsymmetrical ether. .

General scheme for symmetrical ether:

General scheme for unsymmetrical ether:

Tosylation reaction:

When an alcohol is treated with any tosyl chloride (methane sulfonyl chloride) it gets converted into tosylated product and this reaction is called as Tosylation reaction which is shown below:

The reaction of acetyl chloride with amine:

The acyl group of acetyl chloride is very reactive and the chloride group attached to it is a good leaving group. The nucleophile from amine attacks the carbonyl carbon of the acetylchloride to form N- methylacetamide. The chloride group leaves and gets attached to hydrogen of the amine and leaves as hydrochloric acid.

The reaction is: