Using corey - house synthesis we can't prepare `…………………..` from ethylbromide.

Explanation

To solve the question regarding which compound cannot be prepared from ethyl bromide using the Corey-House synthesis, we will follow these steps:

### Step 1: Understand Corey-House Synthesis
Corey-House synthesis involves the reaction of an alkyl halide (like ethyl bromide) with a dialkyl lithium cuprate (R2CuLi). The alkyl halide acts as an electrophile, while the dialkyl lithium cuprate acts as a nucleophile. The reaction proceeds via an SN2 mechanism, resulting in the formation of a new carbon-carbon bond.

### Step 2: Identify the Structure of Ethyl Bromide
Ethyl bromide (C2H5Br) can be represented as:
- R = C2H5 (ethyl group)
- R' = the other alkyl group that will be added to form the final product.

### Step 3: Analyze Possible Products
We need to analyze the given options (A, B, C, D) to determine which compound cannot be formed from ethyl bromide. Each compound can be represented as R-R', where R is the ethyl group (C2H5) and R' is another alkyl group.

1. **Option A**: If the compound can be broken down into an ethyl part and another alkyl part, it can be synthesized.
2. **Option B**: Similar to option A, if it can be broken down into ethyl and another alkyl part, it can be synthesized.
3. **Option C**: If the compound cannot be broken down into an ethyl part and another alkyl part, it cannot be synthesized from ethyl bromide.
4. **Option D**: If it can be broken down into ethyl and another alkyl part, it can be synthesized.

### Step 4: Determine the Correct Answer
After analyzing the options:
- **Option C** is the one that cannot be synthesized from ethyl bromide because it cannot be broken down into an ethyl part and another alkyl part.

### Conclusion
The compound that cannot be prepared from ethyl bromide using Corey-House synthesis is **Option C**.

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