JEE Challenger
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Total Number of Intramolecular Aldol Condensation Products

In the reaction, the total number of intramolecular aldol condensation products formed is

Diagram 0

Official Numerical Answer1

Step-by-Step Solution

To find the total number of intramolecular aldol condensation products formed, let us break down the reaction step-by-step:

Step 1: Reductive Ozonolysis

The starting material is Δ1(6)\Delta^{1(6)}-octalin (bicyclo[4.4.0]dec-1(6)-ene\text{bicyclo[4.4.0]dec-1(6)-ene}), which contains a double bond shared between two fused 6-membered rings.

Treatment with ozone (O3\text{O}_3) followed by reductive workup with zinc and water (Zn/H2O\text{Zn/H}_2\text{O}) cleaves the central double bond:
Bicyclo[4.4.0]dec-1(6)-ene→2. Zn, H2O1. O3Cyclodecane-1,6-dione (Compound Y)\text{Bicyclo[4.4.0]dec-1(6)-ene} \xrightarrow[2.\ \text{Zn, H}_2\text{O}]{1.\ \text{O}_3} \text{Cyclodecane-1,6-dione (Compound } \mathbf{Y}\text{)}

Step 2: Intramolecular Aldol Condensation

  1. Symmetry Analysis of Compound Y\mathbf{Y}:
    Cyclodecane-1,6-dione is a symmetrical 1010-membered ring diketone containing two carbonyl carbons (C1 and C6) and four α\alpha-carbon atoms (C2, C5, C7, and C10). Due to the molecular symmetry (C2vC_{2v} point group), all four α\alpha-carbon atoms are chemically equivalent.

  2. Enolate Formation and Nucleophilic Attack:

    • Deprotonation at any of the four equivalent α\alpha-carbons (for instance, C2) by aqueous NaOH\text{NaOH} forms an enolate ion.
    • The enolate carbon (C2) attacks the carbonyl carbon at C6 in an intramolecular nucleophilic addition.
    • This leads to the formation of a stable 55-membered ring fused with a 77-membered ring (a [5,7][5,7]-bicyclic framework).
  3. Dehydration:

    • Upon heating, the aldol intermediate undergoes dehydration (loss of H2O\text{H}_2\text{O}) to form a stable α,β\alpha,\beta-unsaturated ketone: bicyclo[5.3.0]dec-1(7)-en-2-one.
  4. Uniqueness of Product:

    • Because all four α\alpha-carbon positions are chemically identical, attacking from C2, C5, C7, or C10 yields the exact same structural molecule.
    • Due to ring strain constraints in the 5,7-bicyclic ring system, geometric (E/ZE/Z) isomerism across the double bond is not possible; only the cis-fused double bond geometry exists.

Thus, only 1 intramolecular aldol condensation product is formed.

Final Answer:
The total number of intramolecular aldol condensation products formed is 1.