In which of the following the enol form is dominant over keto form?

Options

A.
B.
C.
D.

Explanation

To determine which compound has a dominant enol form over the keto form, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the Compounds**: We need to analyze the given compounds to see which one has a more stable enol form compared to its keto form.

2. **Analyze the First Compound**:
- The keto form can be converted to the enol form through tautomerization.
- The enol form of this compound can stabilize itself through resonance, forming a six-membered aromatic ring.
- Since the enol form can stabilize itself significantly, it is more stable than the keto form in this case.

3. **Analyze the Second Compound**:
- Convert the keto form to the enol form.
- In this case, the enol form does not have significant resonance stabilization compared to the keto form.
- Therefore, the keto form is more stable here.

4. **Analyze the Third Compound**:
- Again, convert the keto form to the enol form.
- Similar to the second compound, the enol form does not exhibit sufficient stability compared to the keto form.
- Thus, the keto form remains more stable.

5. **Analyze the Fourth Compound**:
- Convert the keto form to the enol form.
- The enol form does not provide enough stabilization compared to the keto form.
- Hence, the keto form is more stable in this case as well.

6. **Conclusion**:
- After analyzing all the options, we find that only the first compound has a dominant enol form over the keto form due to the stability provided by the aromatic resonance.

### Final Answer:
The enol form is dominant over the keto form in the **first compound**.

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