Chapter 21, Problem 21.83P

Interpretation Introduction

Interpretation:

Complete and detail mechanism for the given reaction is to determined.

Concept introduction:

In nucleophilic addition reaction nucleophile is attack on most electrophilic carbon atom results in the formation of new bond between nucleophile and electrophilic carbon atom.

In case of proton transfer reaction proton is abstracted by the electronegative atom like oxygen.

In case of intramolecular Claisen condensation reaction cyclic $\text{β-ketoester}$ is formed. For this reaction base like $\text{NaOEt}$ in presence of ethanol is used. In this reaction proton transfer, nucleophilic addition and nucleophile elimination take place. In this reaction formation of $\text{5 or 6}$ membered ring is take place.

In case of nucleophile elimination, good leaving group $\left({\text{OEt}}^{\text{-}}\right)$ is expelled to reform the carbonyl bond.