JEE Advanced · 2026 · 17 May 2026 · Paper 1 · General Organic Chemistry

Considering ${\mathrm{LiBH}}_4$ reduces an ester group to the corresponding alcohol and does not reduce a carboxylic acid group, the correct statement about the major products P, Q R and S is

1. (A)$\mathbf{P}\&\mathbf{Q}$ are identical, and $\mathbf{R}\&\mathbf{S}$ are diastereomers.
2. (B)$\mathbf{P}\&\mathbf{Q}$ are diastereomers, and $\mathbf{R}\&\mathbf{S}$ are identical.
3. (C)$\mathbf{P}\&\mathbf{Q}$ are diastereomers, and $\mathbf{R}\&\mathbf{S}$ are diastereomers.✓ Correct
4. (D)P & Q are identical, and R & S are identical.

Answer: (C)

Solution

${\mathrm{LiBH}}_4$ selectively reduces ester groups to alcohols but leaves carboxylic acid groups intact.

For the two starting materials shown:

• The first substrate gives product P after reduction
• The second substrate gives product Q after reduction
• Products P and Q are diastereomers (different spatial arrangements)

Similarly, for the other pair:

• Products R and S are also diastereomers

Therefore, both pairs are diastereomers of each other.

JEE Advanced · 2026 · 17 May 2026 · Paper 1 · Single correct option