Chapter 13, Problem 13.48P

Interpretation Introduction

(a)

Interpretation:

How would you carry out the following synthesis is to be suggested.

Concept introduction:

Synthesis of the target molecule is achieved through different chemical reactions involving either reactions that alter the carbon skeleton or the functional group transformation reactions. By observing the target and the given starting compound, the synthesis is planned.

Alkylation of ketone leads to form a new $\text{C-C}$ bond at $\text{α}$ position. For alkylation reaction of ketone, a strong base like $\text{NaOH}$ is used to deprotonate the alpha hydrogen atom which leads to form an enolate ion. This is followed by reaction of this enolate with alkyl halide to add the desired number of carbon atoms at the alpha position of the original ketone.

This alkylated product undergoes an acid-catalyzed halogenation reaction in presence of ${\text{X}}_2$ and acetic acid $\left({\text{CH}}_{\text{3}}\text{COOH}\right)$ which results in the formation of $\text{C-X}$ bond at more substituted $\text{α}$ carbon atom. Dehydrohalogenation reaction leads to the formation of $\text{C=C}$ from halo alkane. This reaction is carried out in the presence of a strong base like ${\text{CH}}_{\text{3}}\text{ONa}$ and heat.

Interpretation Introduction

(b)

Interpretation:

How would you carry out the following synthesis is to be suggested.

Concept introduction:

Synthesis of target molecule is achieved through different chemical reactions involving either reactions that alter the carbon skeleton or the functional group transformation reactions. By observing the target and the given starting compound, the synthesis is planned.

Alkylation of ketone leads to the formation of a new $\text{C-C}$ bond at $\text{α}$ position. For alkylation reaction of ketone a strong base like $\text{NaOH}$ is used to deprotonate the alpha hydrogen atom which leads to form an enolate ion. This is followed by the reaction of this enolate with alkyl halide to add the desired number of carbon atoms at the alpha position of the original ketone.

This alkylated product undergoes a base-catalyzed halogenation reaction in presence of ${\text{X}}_2$ and LDA. This results in the formation of a new $\text{C-X}$ bond at the less substituted $\text{α}$ carbon atom of the ketone. Dehydrohalogenation reaction leads to the formation of $\text{C=C}$ from halo alkane. This reaction is carried out in presence of strong base like ${\text{CH}}_{\text{3}}\text{ONa}$ and heat.