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JEE Main levelSingle correct optionDifficulty 2 of 3co070

Hexane-2,5-dione, , is heated with dilute NaOH (intramolecular aldol condensation). The product is

  1. A3-methylcyclopent-2-en-1-one
  2. B2-methylcyclopent-2-en-1-one
  3. C3-methylcyclohex-2-en-1-one
  4. Dcyclopent-2-en-1-one

Answer: A

The enolate formed at a terminal (C1) attacks the C5 carbonyl, closing a five-membered ring of C1 to C5. Dehydration gives the conjugated enone. The product is 3-methylcyclopent-2-en-1-one. Attack from C3 would give a strained three-membered ring.
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