The option(s) with the correct sequence of reagents for the conversion of **P** to **Q** is(are) ...

The correct option is (C, D). Click to read the detailed step-by-step conceptual solution.

JEE Advanced 2024 Paper 2 Chemistry Question 6 Solution

To convert P to Q, several steps are required:

1. Reduction of alkynes to cis-alkenes using Lindlar's catalyst and $H_2$ .

2. Reduction of the ring ketone to a secondary alcohol using $NaBH_4$ .

3. Conversion of the nitrile ( $-CN$ ) to an aldehyde ( $-CHO$ ) via Stephen reduction ( $SnCl_2/HCl$ followed by hydrolysis).

4. Hydrolysis of the ethyl ester ( $-CO_2Et$ ) to a carboxylic acid ( $-CO_2H$ ) and the acetate ( $-OAc$ ) to a hydroxyl group using $H_3O^+$ .

Options (A) and (B) are incorrect because $NaBH_4$ is used after the aldehyde is formed, which would result in the reduction of the aldehyde to a primary alcohol.

Options (C) and (D) are correct sequences because $NaBH_4$ is used either before the nitrile is reduced or before the aldehyde is released by hydrolysis, and Lindlar's catalyst selectively reduces alkynes without affecting the other functional groups in these sequences.

Question 6

Detailed Solution

1. Reduction of alkynes to cis-alkenes using Lindlar's catalyst and $H_2$ .

2. Reduction of the ring ketone to a secondary alcohol using $NaBH_4$ .

3. Conversion of the nitrile ( $-CN$ ) to an aldehyde ( $-CHO$ ) via Stephen reduction ( $SnCl_2/HCl$ followed by hydrolysis).

4. Hydrolysis of the ethyl ester ( $-CO_2Et$ ) to a carboxylic acid ( $-CO_2H$ ) and the acetate ( $-OAc$ ) to a hydroxyl group using $H_3O^+$ .

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Question 6

Detailed Solution

1. Reduction of alkynes to cis-alkenes using Lindlar's catalyst and H2H_2H2​.

2. Reduction of the ring ketone to a secondary alcohol using NaBH4NaBH_4NaBH4​.

3. Conversion of the nitrile (−CN-CN−CN) to an aldehyde (−CHO-CHO−CHO) via Stephen reduction (SnCl2/HClSnCl_2/HClSnCl2​/HCl followed by hydrolysis).

4. Hydrolysis of the ethyl ester (−CO2Et-CO_2Et−CO2​Et) to a carboxylic acid (−CO2H-CO_2H−CO2​H) and the acetate (−OAc-OAc−OAc) to a hydroxyl group using H3O+H_3O^+H3​O+.

Boost Your Exam Preparation!

1. Reduction of alkynes to cis-alkenes using Lindlar's catalyst and $H_2$ .

2. Reduction of the ring ketone to a secondary alcohol using $NaBH_4$ .

3. Conversion of the nitrile ( $-CN$ ) to an aldehyde ( $-CHO$ ) via Stephen reduction ( $SnCl_2/HCl$ followed by hydrolysis).

4. Hydrolysis of the ethyl ester ( $-CO_2Et$ ) to a carboxylic acid ( $-CO_2H$ ) and the acetate ( $-OAc$ ) to a hydroxyl group using $H_3O^+$ .