Chapter 22.SE, Problem 49AP

Interpretation Introduction

Interpretation:

How to synthesize from the malonic ester the dialkylated intermediate required for the synthesis of aprobarbitol is to be shown. Further a mechanism for the reaction of the intermediate with urea to give aprobarbitol is to be proposed.

Concept introduction:

Removal of both the hydrogens of the active methylene group in malonic ester by treating with LDA and then treating the enolate ions with alkyl halides will yield the dialkylated product.

The steps involved in the reaction of the dialkylated product with urea are i) Nucleophilic attack of nitrogen of urea on the carbonyl carbon of the dialkylated ester ii) Elimination of the ethanol iii) Another nucleophilic attack by second nitrogen of urea on the carbonyl of the other ester group iv) Elimination of another ethanol.

To state:

How to synthesize from the malonic ester the dialkylated intermediate required for the synthesis of aprobarbitol. Further to propose a mechanism for the reaction of the intermediate with urea to give aprobarbitol