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 α-bromo ester with zinc.

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

Accepted Answer

Step 1: Identify the target compound structure. The compound shown is a β-hydroxy ester, which is a typical product of the Reformatsky reaction. The hydroxyl group is attached to the β-carbon relative to the ester group. Step 2: Select the starting materials. For the Reformatsky reaction, you need an α-bromo ester and a carbonyl compound. In this case, the α-bromo ester should correspond to the ester group in the product, and the carbonyl compound should correspond to the β-hydroxy group in the product. Step 3: Prepare the organozinc reagent. Treat the α-bromo ester (e.g., methyl bromoacetate) with zinc metal to form the organozinc reagent. This reagent is less reactive than a Grignard reagent and will selectively react with the carbonyl compound. Step 4: Perform the nucleophilic addition. React the organozinc reagent with the appropriate aldehyde (e.g., isobutyraldehyde) under suitable conditions. The nucleophilic addition occurs at the carbonyl group, forming a β-hydroxy ester intermediate. Step 5: Isolate and purify the product. After the reaction is complete, the β-hydroxy ester can be isolated and purified using standard organic chemistry techniques such as extraction, distillation, or recrystallization.

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Key Concepts

Reformatsky Reaction

Organozinc Reagents

Nucleophilic Addition