Chapter 11.4, Problem 7PTS

(a)

Interpretation Introduction

Interpretation: The reagents that can be used to achieve the following transformation are to be identified.

  

Concept introduction: The given compound is a terminal alkyne that can be converted to an alkene by using various reducing reagents. This then can be reacted with the corresponding alkyl halide for the alkyl coupling to take place, which after subsequent reduction can yield the desired product.

(b)

Interpretation Introduction

Interpretation: The reagents that can be used to achieve each of the following transformations are to be identified.

  

Concept introduction: The starting alkyne is a compound with five carbon atoms, which to be converted into a seven carbon-containing terminal alkyne, needs to undergo a reaction with such reagents which can facilitate this reaction. Reduction using a poisoned catalyst such as Lindlar’s catalyst, followed by bromination and reaction with an alkynide can yield the desired product.

(c)

Interpretation Introduction

Interpretation: The reagents that can be used to achieve each of the following transformations are to be identified.

  

Concept introduction: The starting material has one more carbon atom than the product. This means the synthesis must have an ozonolysis process, to cleave a carbon-carbon bond. Also, since the product is a carboxylic acid, ozonolysis should only happen in an alkyne, as an alkene on ozonolysis would give either an aldehyde or ketone. The alkyne synthesis can be done by double dehydrohalogenation.

(d)

Interpretation Introduction

Interpretation: The reagents that can be used to achieve each of the following transformations are to be identified.

  

Concept introduction: The starting material has six carbon atoms, and the product has nine carbon atoms. So the synthesis must involve the installation of three carbon atoms and also, the location of the functional group has been changed. The starting material is a cis-alkene while the product is a trans-alkene. The starting material must be alkylated with an alkynide which can be reduced with a dissolving metal to yield the product.

(e)

Interpretation Introduction

Interpretation: The reagents that can be used to achieve each of the following transformations is to be identified.

  

Concept introduction: The product has two more carbon atoms than the starting material, and the location of the functional group has changed. So, bromination followed by dehydrohalogenation can give a terminal alkene, which on further bromination followed by reaction with an alkynide would yield the desired product.

(f)

Interpretation Introduction

Interpretation: The reagents that can be used to achieve each of the following transformation is to be identified.

  

Concept introduction: The starting material has one more carbon atom than the product. Therefore, the synthesis must employ an ozonolysis process, to cleave a carbon-carbon bond. For the formation of an aldehyde product, an alkene is also required. For this alkene to be formed, the alcohol must be converted to a tosylate, and then after the alkene is formed, it can undergo ozonolysis to yield the product.