Chapter 22, Problem

Interpretation Introduction

(a)

Interpretation: The stepwise mechanism for the reaction of $\text{ethyl hexa-2, 4-dienoate}$ with diethyl oxalate in the presence of base is to be drawn.

Concept introduction: Claisen condensation takes place between two esters or between an ester and a ketone. In crossed Claisen condensation reaction, a base abstracts an acidic proton from an $\text{α}$ carbon atom of carbonyl compound to form an enolate. This enolate reacts with carbonyl group of other carbonyl compounds that lead to the formation of $\text{β}$-ketoester.

Interpretation Introduction

(b)

Interpretation: An explanation regarding the formation of a new carbon-carbon bond on $\text{C6}$ with the help of mechanism is to be stated.

Concept introduction: Claisen condensation takes place between two esters or between an ester and a ketone. In crossed Claisen condensation reaction, a base abstracts an acidic proton from an $\text{α}$ carbon atom of carbonyl compound to form an enolate. This enolate reacts with carbonyl group of other carbonyl compounds that lead to the formation of $\text{β}$-ketoester.

Interpretation Introduction

(c)

Interpretation: The reason as to why the given reaction is an example of a crossed Claisen reaction is to be stated.

Concept introduction: Claisen condensation takes place between two esters or between an ester and a ketone. In crossed Claisen condensation reaction, a base abstracts an acidic proton from an $\text{α}$ carbon atom of carbonyl compound to form an enolate. This enolate reacts with carbonyl group of other carbonyl compounds that lead to the formation of $\text{β}$-ketoester.