In the following reaction 'B' is
The Correct Option is D
Solution and Explanation
Acid-Catalyzed Cyclization Mechanism
The given reaction is an acid-catalyzed intramolecular cyclization of an unsaturated alcohol. The mechanism involves:
- Protonation of the alcohol: The hydroxyl group is protonated by \(\text{H}_3\text{O}^+\), making it a better leaving group.
- Carbocation formation: Water leaves, generating a secondary carbocation.
- Cyclization: The double bond attacks the carbocation, forming a six-membered ring. This results in a tertiary carbocation. Crucially, this carbocation is formed adjacent to the oxygen in the newly formed ring.
- Deprotonation: A proton is lost to give the final cyclic ether product.
The correct product, resulting from the more stable tertiary carbocation and forming the six-membered ring, is option (4).
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