Which of the following reaction will give `beta`-keto aldehyde as the final product ?

Options

A.
B.
C.
D. All of these

Explanation

To determine which reaction will give a beta-keto aldehyde as the final product, we need to analyze the provided options step by step.

### Step 1: Understanding Beta-Keto Aldehyde
A beta-keto aldehyde is a compound that contains both a ketone (C=O) and an aldehyde (C=O) functional group, with the ketone group located at the beta position relative to the aldehyde.

### Step 2: Analyzing the Reactions
We are given four options (A, B, C, D) that describe different reactions. We need to identify which of these reactions will lead to the formation of a beta-keto aldehyde.

### Step 3: Reaction in Option A
In option A, we have cyclohexanone reacting with an aldehyde (HCO) in the presence of sodium ethoxide (C2H5O^- Na^+) and an acidic medium (H^+).

1. **Cyclohexanone Structure**: Cyclohexanone has a carbonyl group (C=O) attached to a cyclohexane ring.
2. **Aldehyde Structure**: The aldehyde (HCO) has a carbonyl group (C=O) at the end of the carbon chain.
3. **Mechanism**: The oxygen of the carbonyl in cyclohexanone acts as a nucleophile and attacks the electrophilic carbon of the aldehyde. This leads to the formation of a new carbon-carbon bond, resulting in a compound that has both a ketone and an aldehyde.

### Step 4: Identifying the Product
After the reaction, we analyze the structure:
- The cyclohexanone retains its carbonyl group.
- The newly formed compound has the aldehyde at the alpha position and the ketone at the beta position.

Thus, the final product from option A is indeed a beta-keto aldehyde.

### Step 5: Conclusion
After analyzing all options, we conclude that:
- **Option A** is the only reaction that results in the formation of a beta-keto aldehyde.
- Options B, C, and D do not yield a beta-keto aldehyde.

### Final Answer
The correct answer to the question is **Option A**.

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