Reagent(s) which can be used to bring about the following transformation is(are)

1. $\mathrm{L}\mathrm{i}\mathrm{A}\mathrm{l}{\mathrm{H}}_4$ in ${\left({\mathrm{C}}_2{\mathrm{H}}_5\right)}_2\mathrm{O}$
2. $\mathrm{B}{\mathrm{H}}_3$ in $\mathrm{THF}$
3. $\mathrm{N}\mathrm{a}\mathrm{B}{\mathrm{H}}_4$ in ${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{O}\mathrm{H}\mathrm{ }$
4. Raney $\mathrm{Ni}/{\mathrm{H}}_2$ in $\mathrm{THF}$

Solution

$\mathrm{L}\mathrm{i}\mathrm{A}\mathrm{l}{\mathrm{H}}_4$ in ${\left({\mathrm{C}}_2{\mathrm{H}}_5\right)}_2\mathrm{O}$, $\mathrm{B}{\mathrm{H}}_3$ in ($\mathrm{THF}$), Raney  $\mathrm{Ni}/{\mathrm{H}}_2$ either can reduce all functional groups or can reduce some of the functional groups of the compound given above in the reactant side. But, $\mathrm{N}\mathrm{a}\mathrm{B}{\mathrm{H}}_4$ is an example of selective reducing agent. It cannot reduce, (ester group) , (carboxylic acid group) , (epoxide group). But reduces $-\mathrm{C}\mathrm{H}=\mathrm{O}$ (aldehyde group) into $-\mathrm{C}{\mathrm{H}}_2\mathrm{O}\mathrm{H}\mathrm{ }\left(1^{\mathrm{o}}\mathrm{ }\mathrm{a}\mathrm{l}\mathrm{c}\mathrm{o}\mathrm{h}\mathrm{o}\mathrm{l}\right)$.

Asked in: JEE Advanced 2016 (Paper 2)

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