For an unambiguous single step synthesis of the following target molecule (TM), the best bond disconnection in its retrosynthetic analysis is:
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When analyzing Beta-keto esters in retrosynthesis, always consider the Claisen condensation pathway. The best disconnection is often at the bond between the Alpha-carbon and the carbonyl group, forming enolate and ester precursors.
The target molecule (TM) is a β-keto diester, which can be synthesized in a single step via a Claisen condensation. In a Claisen condensation, an ester enolate reacts with another ester or a carbonyl compound to form a β-keto ester.
To apply this in retrosynthesis:
Identify the position of the β-keto group and the two ester functionalities.
The disconnection should occur between the \( \alpha \)-carbon of one ester and the carbonyl carbon of another ester.
In option (B), the disconnection leads to the formation of two plausible starting materials:
Ethyl acetoacetate (a common β-keto ester)
Diethyl carbonate or another ester to perform the Claisen condensation
This gives a clear, unambiguous, and synthetically accessible path in one step.
\[
\boxed{\text{Best disconnection: Option (B) via Claisen condensation}}
\]
