Predict the major product ‘P’ in the following sequence of reactions-

The correct option is the fourth option (Option 4), which represents 1-methyl-2-(aminomethyl)cyclopentane (or (2-methylcyclopentyl)methanamine).

Let us break down the reaction sequence step-by-step to understand how the major product ��P’ is formed:

Step 1: Anti-Markovnikov addition of HBr (Kharasch effect)
When 1-methylcyclopentene (a cyclopentene ring with a methyl substituent on one of the double-bonded carbons, C1) is treated with hydrogen bromide (HBr) in the presence of benzoyl peroxide, the reaction proceeds via a free-radical chain mechanism:
1. The peroxide initiator decomposes to form free radicals, which react with HBr to generate a bromine radical:
${\text{Br}}^{•}$
2. The bromine radical attacks the alkene double bond. It selectively adds to the less-substituted carbon (C2) to form a more stable tertiary radical at the C1 position (bearing the methyl group) rather than a secondary radical.
3. The tertiary radical then abstracts a hydrogen atom from a molecule of HBr, yielding the anti-Markovnikov product:
1-bromo-2-methylcyclopentane

Step 2: Nucleophilic Substitution (${\text{S}}_{\text{N}}2$ reaction)
When 1-bromo-2-methylcyclopentane is reacted with potassium cyanide (KCN):
The cyanide ion (${\text{CN}}^{-}$) acts as a nucleophile and undergoes nucleophilic substitution, replacing the bromide ion (${\text{Br}}^{-}$) at the secondary carbon (C2). This yields:
1-cyano-2-methylcyclopentane (2-methylcyclopentanecarbonitrile)

Step 3: Mendius Reduction of the Nitrile
Treating the nitrile with sodium amalgam in ethanol ($\text{Na}\left(\text{Hg}\right)/{\text{C}}_2{\text{H}}_5\text{OH}$) reduces the nitrile group ($-\text{C}\equiv \text{N}$) to a primary amine group ($-{\text{CH}}_2{\text{NH}}_2$):
This Mendius reduction converts 1-cyano-2-methylcyclopentane into:
1-methyl-2-(aminomethyl)cyclopentane (also named (2-methylcyclopentyl)methanamine), where the methyl group ($-{\text{CH}}_3$) and the aminomethyl group ($-{\text{CH}}_2{\text{NH}}_2$) are located on adjacent carbons of the cyclopentane ring.

This structure corresponds directly to the one shown in Option 4 (Image 4).