Among the following compounds which one will produce an enamine on reaction with cyclohexanone?

Options

A.
B.
C.
D.

Answer

To determine which compound will produce an enamine upon reaction with cyclohexanone, we need to follow these steps:

### Step 1: Understand what an enamine is
An enamine is a compound that contains both a double bond (ene) and an amine group (amine). It is formed when a secondary amine reacts with a carbonyl compound, such as a ketone or aldehyde, followed by dehydration.

### Step 2: Identify the reaction conditions
The reaction involves a secondary amine reacting with cyclohexanone (a ketone). The general reaction can be summarized as follows:
1. The amine attacks the carbonyl carbon of cyclohexanone.
2. A tetrahedral intermediate is formed.
3. A water molecule is eliminated, resulting in the formation of an enamine.

### Step 3: Analyze the options
We need to evaluate each of the provided compounds to see if they can act as a secondary amine and produce an enamine with cyclohexanone.

1. **Option 1**: This compound does not have a hydrogen atom on the nitrogen that is necessary for tautomerization, so it cannot form an enamine.

2. **Option 2**: This compound is a secondary amine. When it reacts with cyclohexanone, it can form an enamine. The reaction proceeds as follows:
- The nitrogen atom attacks the carbonyl carbon of cyclohexanone.
- A tetrahedral intermediate is formed, which then loses a water molecule to form the enamine.

3. **Option 3**: This compound does not have the right structure to form an enamine upon reaction with cyclohexanone.

4. **Option 4**: Similar to option 3, this compound also does not have the necessary structure to produce an enamine.

### Step 4: Conclusion
Based on the analysis, the compound that will produce an enamine on reaction with cyclohexanone is **Option 2**.