Question

The Reformatsky reaction is an addition reaction in which an organozinc reagent is used instead of a Grignard reagent to add to the carbonyl group of an aldehyde or a ketone. Because the organozinc reagent is less reactive than a Grignard reagent, a nucleophilic addition to the ester group does not occur. The organozinc reagent is prepared by treating an ß-bromo ester with zinc.

Describe how each of the following compounds can be prepared, using a Reformatsky reaction:

Short answer

The Reformatsky reaction is an addition reaction in which an organozinc reagent is used instead of a Grignard reagent to add to the carbonyl group of an aldehyde or a ketone. Because the organozinc reagent is less reactive than a Grignard reagent, a nucleophilic addition to the ester group does not occur. The organozinc reagent is prepared by treating an ß -bromo ester with zinc.

Step-by-step solution

Reformatsky Reaction

The Reformatsky reaction is an addition reaction in which an organozinc reagent is used instead of a Grignard reagent to add to the carbonyl group of an aldehyde or a ketone. Because the organozinc reagent is less reactive than a Grignard reagent, a nucleophilic addition to the ester group does not occur. The organozinc reagent is prepared by treating an ß -bromo ester with zinc.

Synthesizing the given compounds using Reformatsky reaction

(a) In this reaction, butanal undergoes Reformatsky reaction with methyl bromoaceate in the presence of water to produce methyl-3-hydroxyhexanoate, which is our desired product as shown in the figure given below:

(b) In this reaction synthesis, propanal undergoes Reformatsky reaction with methyl-2- bromobutanoate to produce methyl-2-ethyl-3-hydroxypentanoate, which on further hydrolysis gives our desired product as shown in the figure given below:

(c) In this reaction synthesis, propanal undergoes Reformatsky reaction with methyl-2- bromopropanoate to produce methyl-3-hydroxy-2-methylpentanoate, which on further undergoes reaction with acids for the removal of hydroxyl group to form our desired product as shown in the figure given below:

(d) In this reaction, hexan-3-one undergoes Reformatsky reaction with methyl bromoaceate in the presence of water to produce methyl-3-ethyl-3-hydroxypentanoate, which is our desired product as shown in the figure given below: