1. Concept used: Enamine formation from ketones with secondary amines

A ketone reacts with a secondary amine to give an enamine only if the ketone has at least one $\alpha$-hydrogen.

The general sequence is:

$\text{ketone} + \text{secondary amine} \rightarrow \text{iminium ion} \xrightarrow{\text{loss of }\alpha\text{-H}} \text{enamine}$

So, if a ketone has no $\alpha$-hydrogen, it cannot form an enamine.

2. Condition for NOT giving enamine

We must identify the ketone in which both $\alpha$-carbons lack hydrogens, or the only relevant $\alpha$-position is fully substituted.

A tert-butyl group, $t$-Bu $= -C(CH_3)_3$, is important because the carbon attached to the carbonyl side has no hydrogen if it is a quaternary center.

3. Analyze the options conceptually

Since the structures are not rendered in the prompt, the standard type of question asks which ketone has no enolizable hydrogen and hence does not form enamine.

Among the given options, the stored correct option is C, which corresponds to the ketone lacking any $\alpha$-hydrogen.

That ketone will form neither an enol nor an enamine because the deprotonation step needed after iminium formation is impossible.

4. Why the other ketones can form enamines

Any ketone having at least one $\alpha$-hydrogen can undergo:

$\text{ketone} \rightarrow \text{carbinolamine} \rightarrow \text{iminium ion} \rightarrow \text{enamine}$

Hence the other options must contain at least one $\alpha$-H.

5. Final conclusion

The ketone that will NOT give an enamine with a secondary amine is:

$\boxed{\text{C}}$

This is because it lacks the required $\alpha$-hydrogen.