Chapter 19.6, Problem 21ATS

(a)

Interpretation Introduction

Interpretation: The structure of proline has to be drawn:

Concept Introduction:

Enamine formation:

Aldehyde or ketone reacts with a secondary amine and forms enamine in mildly acidic conditions.

Example for the formation of enamine is shown here:

In enamines, the lone pair of nitrogen will be in resonance with the adjacent $\text{C=C}$.

Retro synthetic analysis:

It is the analysis of the synthetic starting materials for a given compound through its precursors or fragments which are known as synthons. The synthons can be obtained by logical cleavage of the chemical bonds in the compounds. The resulted synthons will be therefore known as logical synthons.

Retro analysis for enamine formation:

The retro analysis of enamine reveals that the starting material of an enamine will be a secondary amine and a carbonyl compound.

Example:

(b)

Interpretation Introduction

Interpretation: The plausible mechanism for the reaction between compounds 1 and 2 has to be drawn.

Concept Introduction:

Enamine formation:

Aldehyde or ketone reacts with a secondary amine and forms enamine in mildly acidic conditions.

Example for the formation of enamine is shown here:

In enamines, the lone pair of nitrogen will be in resonance with the adjacent $\text{C=C}$.