Question 15

The reaction sequence involves:

1. Ozonolysis of the tetrasubstituted double bond to yield a dicarbonyl (diketone).
2. Intramolecular Aldol condensation of the resulting diketone under basic conditions ($NaOH$).
3. Cyclization follows the formation of the more stable enolate and results in the most stable ring system (usually 5 or 6 membered rings).

• (P) is a 6-6 fused system ($C_{12}H_{18}$). Ozonolysis gives a 10-membered ring diketone. Intramolecular aldol cyclization leads to a 6-6 fused hydroxy-ketone, which is product (2).
• (Q) is a 6-7 fused system ($C_{13}H_{20}$). Ozonolysis gives an 11-membered ring diketone. Cyclization leads to a 6-7 fused hydroxy-ketone, which is product (1).
• (R) is a 7-5 fused system ($C_{12}H_{18}$). Ozonolysis gives a 10-membered ring diketone. Cyclization leads to a stable 6-6 fused hydroxy-ketone system, which is product (5).
• (S) is a 6-5 fused system ($C_{11}H_{16}$). Ozonolysis gives a 9-membered ring diketone. Cyclization leads to a 6-5 fused hydroxy-ketone, which is product (3).

Therefore, the correct matching is P-2, Q-1, R-5, S-3. Correct Option: C