Matching Reaction Sequences to Diol Products in Cyclic Alkenes and Ketones

To determine the correct matching between the reaction sequences in List-I and the final products in List-II, we analyze each sequence step-by-step:

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Reaction (P)

1. $\text{O}_3, \text{Zn}$ (Reductive Ozonolysis):
   Cleavage of the double bond in cyclohexene yields hexanedial:
   $\text{OHC}-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CHO}$

2. $\text{aq. NaOH}, \Delta$ (Intramolecular Aldol Condensation):
   An enolate formed at $\text{C}_2$ attacks the carbonyl carbon at $\text{C}_6$, forming a 5-membered ring. Upon dehydration, this yields cyclopent-1-ene-1-carbaldehyde.

3. Ethylene glycol, PTSA (Acetal Protection):
   Protects the aldehyde ($-\text{CHO}$) group as a cyclic acetal ($1,3$-dioxolane ring) while leaving the alkene double bond intact, giving 2-(cyclopent-1-en-1-yl)-1,3-dioxolane.

4. a) $\text{BH}_3$, b) $\text{H}_2\text{O}_2, \text{NaOH}$ (Hydroboration-Oxidation):
   Adds $-\text{H}$ and $-\text{OH}$ across the double bond in an anti-Markovnikov manner. The $-\text{OH}$ group attaches to the less substituted carbon ($\text{C}_2$ of the ring).

5. $\text{H}_3\text{O}^+$ (Deprotection):
   Hydrolyzes the acetal back to the aldehyde group ($-\text{CHO}$).

6. $\text{NaBH}_4$ (Reduction):
   Reduces the aldehyde group ($-\text{CHO}$) to a primary alcohol ($-\text{CH}_2\text{OH}$).
   Product: $2-(\text{hydroxymethyl})\text{cyclopentan-1-ol}$, which corresponds to (3) in List-II.

   $\mathbf{P \rightarrow 3}$

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Reaction (Q)

1. $\text{O}_3, \text{Zn}$ (Reductive Ozonolysis):
   Cleavage of $1$-methylcyclohex-$1$-ene yields $6$-oxoheptanal:
   $\text{CH}_3-\text{C}(=\text{O})-\text{CH}_2-\text{CH}_2-\text{CH}_2-\text{CHO}$

2. $\text{aq. NaOH}, \Delta$ (Intramolecular Aldol Condensation):
   The enolate at $\text{C}_5$ (alpha to the ketone) attacks the more electrophilic aldehyde carbon ($\text{C}_1$), forming a 5-membered ring. Dehydration gives $1$-acetylcyclopent-$1$-ene:
   $\text{Cyclopent-1-en-1-yl ethanone}$

3. Ethylene glycol, PTSA (Ketal Protection):
   Protects the acetyl ketone ($-\text{COCH}_3$) group as a cyclic ketal.

4. a) $\text{BH}_3$, b) $\text{H}_2\text{O}_2, \text{NaOH}$ (Hydroboration-Oxidation):
   Anti-Markovnikov addition of $-\text{OH}$ to the less substituted alkene carbon ($\text{C}_2'$ of the ring).

5. $\text{H}_3\text{O}^+$ (Deprotection):
   Hydrolyzes the ketal back to the methyl ketone group ($-\text{COCH}_3$).

6. $\text{NaBH}_4$ (Reduction):
   Reduces the ketone ($-\text{COCH}_3$) to a secondary alcohol ($-\text{CH}(\text{OH})\text{CH}_3$).
   Product: $2-(1-\text{hydroxyethyl})\text{cyclopentan-1-ol}$, which corresponds to (5) in List-II.

   $\mathbf{Q \rightarrow 5}$

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Reaction (R)

1. Ethylene glycol, PTSA (Ketal Protection):
   Protects the carbonyl group of $2$-methylcyclopent-$2$-en-$1$-one as a cyclic ketal, preserving the double bond.

2. a) $\text{Hg}(\text{OAc})_2, \text{H}_2\text{O}$, b) $\text{NaBH}_4$ (Oxymercuration-Demercuration):
   Markovnikov addition of $-\text{OH}$ and $-\text{H}$ without rearrangement. The $-\text{OH}$ group attaches to the more substituted carbon ($\text{C}_2$, which bears the methyl group).

3. $\text{H}_3\text{O}^+$ (Deprotection):
   Hydrolyzes the ketal back to the ketone at $\text{C}_1$.

4. $\text{NaBH}_4$ (Reduction):
   Reduces the ketone at $\text{C}_1$ to a secondary alcohol group ($-\text{OH}$).
   Product: $1$-methylcyclopentane-$1,2$-diol, which corresponds to (4) in List-II.

   $\mathbf{R \rightarrow 4}$

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Reaction (S)

1. Ethylene glycol, PTSA (Ketal Protection):
   Protects the carbonyl group of $2$-methylcyclopent-$2$-en-$1$-one as a cyclic ketal.

2. a) $\text{BH}_3$, b) $\text{H}_2\text{O}_2, \text{NaOH}$ (Hydroboration-Oxidation):
   Anti-Markovnikov addition across the double bond placing $-\text{OH}$ at the less substituted carbon ($\text{C}_3$) and $-\text{H}$ at the methyl-bearing carbon ($\text{C}_2$).

3. $\text{H}_3\text{O}^+$ (Deprotection):
   Hydrolyzes the ketal back to the ketone at $\text{C}_1$.

4. $\text{NaBH}_4$ (Reduction):
   Reduces the ketone at $\text{C}_1$ to a secondary alcohol group ($-\text{OH}$).
   Product: $2$-methylcyclopentane-$1,3$-diol, which corresponds to (1) in List-II.

   $\mathbf{S \rightarrow 1}$

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Conclusion:

Matching each entry:

• $\text{P} \rightarrow 3$
• $\text{Q} \rightarrow 5$
• $\text{R} \rightarrow 4$
• $\text{S} \rightarrow 1$

This set of matches corresponds to Option (A).