Discussion
The major products Y and Z in the following reaction sequence are
- A.
- B.
- C.
- D.
Answer: B
The answer is (B): Y is the N,N-bis(2-ethoxycarbonylethyl)aniline, Z is 1-phenylpiperidin-4-one.
With excess ethyl acrylate, the aniline nitrogen adds twice in a Michael reaction, giving the tertiary amine with two CH2CH2CO2Et arms (Y). Sodium ethoxide then drives a Dieckmann condensation: the carbon next to one ester attacks the other ester, closing a six-membered ring and forming a β-keto ester. Hydrolysis with NaOH, acidification and heating then loses CO2 (decarboxylation) and leaves the 4-piperidone.
(A) and (C) show only a single addition, which excess acrylate rules out. (D) has the right Y but closes a five-membered ring, which does not form here.
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