Chapter 21, Problem 21.33P

Interpretation Introduction

Interpretation:

It is to be shown how to carry out the given synthesis.

Concept introduction:

The protection of a carboxylic acid group under neutral condition is done by using diazomethane (${\text{CH}}_{\text{2}}{\text{N}}_{\text{2}}$). Chromic acid (${\text{H}}_{\text{2}}{\text{CrO}}_{\text{4}}$) is a strong oxidizing agent and oxidizes primary alcohol to carboxylic acid. An acid chloride ($\text{RCOCl}$), on treatment with lithium dialkylcuprate (${\text{R}}_{\text{2}}\text{CuLi}$), produces the corresponding ketone (${\text{R}}_{\text{2}}\text{C=O}$). Lithium dialkylcuprate (${\text{R}}_{\text{2}}\text{CuLi}$) is a source of the weak nucleophile ${\text{R}}^{\text{-}}$ and does not react with ketones or aldehydes via direct addition. Esters and amides are more stable than acid chloride and do not react with lithium dialkylcuprate (${\text{R}}_{\text{2}}\text{CuLi}$). Thus, to convert amide or ester to a ketone, they must be first converted to an acid chloride.