Which of the following compounds would undergo Diels-Alder reaction with dienophile (e.g., Maleic anhydride) ?

Options

A. `HC -= C - C -= CH`
B.
C.
D.

Answer

To determine which of the given compounds would undergo a Diels-Alder reaction with a dienophile such as maleic anhydride, we need to analyze the structural requirements for the Diels-Alder reaction.

### Step-by-Step Solution:

1. **Understanding the Diels-Alder Reaction**:
The Diels-Alder reaction is a [4+2] cycloaddition reaction between a diene and a dienophile. For a compound to act as a diene, it must have at least two conjugated double bonds (a diene system) that can react with a dienophile.

2. **Identifying the Diene**:
- A diene must have two double bonds that are in a conjugated system.
- The diene should preferably be in a cis configuration to allow for effective overlap of orbitals during the reaction.

3. **Electron Donating and Withdrawing Groups**:
- The diene should have an electron-donating group (EDG) that enhances its reactivity.
- The dienophile (like maleic anhydride) should have an electron-withdrawing group (EWG) to facilitate the reaction.

4. **Analyzing Each Compound**:
- **Compound A**: Check if it has a diene structure. If it is a di-ine (more than two double bonds), it does not qualify as a diene for this reaction.
- **Compound B**: Identify if it has a diene. If the diene is not in the same ring, it cannot participate in the Diels-Alder reaction.
- **Compound C**: Check the configuration of the double bonds. If the diene is in a trans configuration, it will not effectively overlap with the dienophile.
- **Compound D**: Confirm if it has a diene in the same ring and if there is an electron-donating group present.

5. **Conclusion**:
After analyzing the compounds based on the above criteria, we find that **Compound D** meets all the necessary conditions for undergoing a Diels-Alder reaction with maleic anhydride.

### Final Answer:
The compound that would undergo a Diels-Alder reaction with a dienophile (e.g., Maleic anhydride) is **Compound D**.