Which of the following pairs of starting materials can be used to synthesize ${\mathrm{CH}}_3\mathrm{COCH}{2}_2\mathrm{CH}{2}_1\mathrm{COOEt}$ via a Michael addition reaction?

• A. $\mathrm{Ethyl}\mathrm{acetoacetate}$ and $\mathrm{methyl}\mathrm{vinyl}\mathrm{ketone}$
• B. $\mathrm{Acetone}$ and $\mathrm{ethyl}\mathrm{acetoacetate}$
• C. $\mathrm{Diethyl}\mathrm{malonate}$ and $\mathrm{benzaldehyde}$
• D. $\mathrm{Acetophenone}$ and $\mathrm{ethyl}\mathrm{acetoacetate}$

Answer: (A)

Verified step by step guidance

1. Identify the structure of the target molecule: CH3COCH2CH2COOEt, which contains a ketone and an ester separated by a two-carbon chain, suggesting a 1,4-addition (Michael addition) product.
2. Recall that a Michael addition involves the nucleophilic addition of an enolate ion (from a compound with acidic alpha hydrogens) to an α,β-unsaturated carbonyl compound (Michael acceptor).
3. Determine which starting materials can act as the Michael donor (nucleophile) and which as the Michael acceptor (electrophile). The donor should be a compound capable of forming a stabilized enolate, such as ethyl acetoacetate or diethyl malonate.
4. The acceptor should be an α,β-unsaturated carbonyl compound like methyl vinyl ketone, which has a conjugated double bond adjacent to a carbonyl, making it susceptible to nucleophilic attack at the β-carbon.
5. Match the pairs: ethyl acetoacetate (donor) and methyl vinyl ketone (acceptor) fit the criteria for a Michael addition to form the target molecule, while other pairs either lack the necessary conjugation or enolate formation ability.