In each reaction box (3 boxes total), place the best reagent or reactant from the list below

reagent-reaction
reactant

#1

In each reaction box (3 boxes total), place the best reagent or reactant from the list below.

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Concepts and reason
The concept used to solve this problem is by using the given reagents, possible products will be formed in each step and then label it exactly in the given boxes in order to form the exact product.
Here, the starting reactant is benzyl alcohol and the final product is 2-(benzyloxy)acetaldehyde.

Fundamentals
Sodium hydride (NaH) is used as base, which abstract the proton.
PCC is used as an oxidizing agent for the conversion of primary alcohol to aldehyde.
Phosphorous tribromide is used for the conversion of alcohol to alkyl bromide.
Sodium borohydride is used as a reducing agent for the conversion of aldehyde to primary alcohol and ketone to secondary alcohol.

Answer:

The reaction is as follows:
image

The reaction is as follows:

The reaction is as follows:

The reaction is as follows:

The best reagents that are used for the conversion of benzyl alcohol to 2-(benzyloxy)acetaldehyde are as follows:
image