The structures of major products A, B and C in the following reaction sequence are:

1. Formation of Product [A]

The starting material is 2-methylpentanal. It is treated with $$\text{NaHSO}_3$$, $$\text{dil. HCl}$$, $$\text{NaCN}$$, and $$\text{H}_2\text{O}$$, which are the standard reagents for cyanohydrin formation via the bisulfite addition pathway.

• Mechanism: The aldehyde group ($$-\text{CHO}$$) undergoes nucleophilic addition by the cyanide ion ($$\text{CN}^-$$), followed by protonation to yield a cyanohydrin.
• Structure of [A]:
  $$A = \text{CH}_3\text{CH}_2\text{CH}_2\text{CH(CH}_3)\text{CH(OH)CN}$$
  

2. Formation of Product [B]

Product [A] (the cyanohydrin) is treated with Lithium Aluminum Hydride ($$\text{LiAlH}_4$$), a powerful reducing agent.

• Mechanism: $$\text{LiAlH}_4$$ reduces the nitrile group ($$-\text{CN}$$) down to a primary amine group ($$-\text{CH}_2\text{NH}_2$$). The alcohol group ($$-\text{OH}$$) remains unaffected after workup.
• Structure of [B]:
  $$B = \text{CH}_3\text{CH}_2\text{CH}_2\text{CH(CH}_3)\text{CH(OH)CH}_2\text{NH}_2$$

3. Formation of Product [C]

Product [A] is treated with $$\text{HCl}/\text{H}_2\text{O}$$ and heated ($$\Delta$$).

• Mechanism: Acidic hydrolysis of a nitrile group ($$-\text{CN}$$) converts it into a carboxylic acid group ($$-\text{COOH}$$). Because it is a cyanohydrin, this yields a $$\alpha$$-hydroxy acid.
• Structure of [C]:$$C = \text{CH}_3\text{CH}_2\text{CH}_2\text{CH(CH}_3)\text{CH(OH)COOH}$$