Chapter 20, Problem 20.48P

Interpretation Introduction

(a)

Interpretation:

How the given transformation can be carried out is to be explained.

Concept introduction:

The diisobutylaluminum hydride $\text{(DIBAH, or DIBAL-H)}$ is the reducing agent that can stop the reduction of ester or carboxylic acid to aldehyde. A conjugated ester can be reduced to an aldehyde without reducing it further to alcohol using a specific reagent such as ${\text{DIBAH, then H}}_{\text{3}}{\text{O}}^{+}$. The single hydride ion from ${\text{DIBAH, then H}}_{\text{3}}{\text{O}}^{+}$ adds to the carbonyl of a carboxylic acid, reducing it to an aldehyde in acidic condition. It does not reduce the $\text{C=C}$ bond in the compound.

Interpretation Introduction

(b)

Interpretation:

How the given transformation can be carried out is to be explained.

Concept introduction:

The Lithiumaluminum hydride ${\text{(LiAlH}}_{\text{4}}\text{)}$ is the reducing agent that can reduce carbonyls to corresponding alcohol. The conjugated ester can be reduced to an aldehyde, which is further reduced to an alcohol using a specific reagent as ${\text{(LiAlH}}_{\text{4}}\text{)}$. It does not reduce the $\text{C=C}$ bond in the compound.

Interpretation Introduction

(c)

Interpretation:

How the given transformation can be carried out is to be explained.

Concept introduction:

An acid chloride can be converted to an aldehyde by reacting it with ${\text{LiAlH(O-t-Bu)}}_{\text{3}}$. The ${\text{LiAlH(O-t-Bu)}}_{\text{3}}$ is a source of hydride ion, which acts as a nucleophile and reduces the acid derivative to an aldehyde by elimination of chloride ion. It does not reduce the $\text{C=C}$ bond in the compound.

Interpretation Introduction

(d)

Interpretation:

How the given transformation can be carried out is to be explained.

Concept introduction:

The Lithiumaluminum hydride ${\text{(LiAlH}}_{\text{4}}\text{)}$ is the reducing agent that can reduce carbonyls to corresponding alcohols. The acid chloride can be reduced to an aldehyde, which is further reduced to alcohol using a specific reagent as ${\text{(LiAlH}}_{\text{4}}\text{)}$. It does not reduce the $\text{C=C}$ bond in the compound.