Chapter 19.9, Problem CQ

Interpretation Introduction

Interpretation:

The type of reaction which converts the structure B to ibuprofen in synthesis I has to be identified.

Concept introduction:

Malonic ester synthesis is used to prepare carboxylic acids of the desired length. The malonic ester reacts with an alkoxide base which removes a $\alpha$ hydrogen atom.  The anion so formed is reacted with an alkyl bromide.  Th anion abstracts the alkyl group from the alkyl bromide. Acidic hydrolysis of the intermediate so formed gives $\alpha -\text{substituted}$ malonic acid. On heating, decarboxylation takes place which gives the desired carboxylic acid.