Chapter 20, Problem 20.59P

Interpretation Introduction

Interpretation:

The lactam treated with $\text{LDA}$ gives ring expanded lactam; the detailed mechanism for this reaction is to be predicted.

Concept introduction:

It is a nucleophilic addition-elimination reaction. The reaction is carried out under basic condition $\left(\text{LDA}\right)$, and hence no strong acid should appear. The cyclic amide, i.e., lactam in which ${\text{NH}}_{\text{2}}$ group is present acts as a nucleophile in this nucleophilic addition-elimination reaction. The first nucleophilic addition followed by the nucleophilic elimination step gives the final ring expanded lactam.