Chapter 20, Problem 20.20P

Interpretation Introduction

Interpretation:

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

Concept introduction:

An amide (RCONR2), on treatment with lithium aluminum hydride $\left({\text{LiAlH}}_{\text{4}}\right)$, is reduced to the corresponding amine, preserving the overall carbon backbone of the original amide. When both ketone and ester group are present in a compound, both are reduced by ${\text{LiAlH}}_{\text{4}}$. To reduce the amide group selectively, the ketone group must be protected. Ketone, on treatment with $\text{1, 2-diol}$ in acidic medium, produces five-membered ring acetal, which is stable under the basic condition and not reduced by ${\text{LiAlH}}_{\text{4}}$. So the ketone is protected in the form of acetals. For the deprotection, dilute acid is used.