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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3o4055

Which statements are correct for the conversion of hexane-2,5-dione into 3-methylcyclopent-2-en-1-one with dilute ?

  1. AThe first step is an intramolecular aldol addition.
  2. BThe dehydration proceeds by E1cB via an enolate.
  3. CThe product is a conjugated enone.
  4. DThe ring-forming step produces a six-membered ring.

Answer: A, B, C

An enolate of one carbonyl attacks the other, forming a five-membered ring and the beta-hydroxy ketone 3-hydroxy-3-methylcyclopentanone. This dehydrates by E1cB through an enolate to the conjugated enone. The ring formed is five-membered, not six.
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