Q7(d). Intramolecular aldol condensation of a dialdehyde
Base catalyzed condensation of dialdehyde A can result in the formation of two products (P, Q). Identify the two products. Which one is actually obtained and why? Also give the mechanism of its formation. [Structure of A given in the paper; reagent dil. NaOH]
Answer in brief
P = 3-(propan-2-yl)cyclopent-1-ene-1-carbaldehyde, a conjugated enal. Q = 2-hydroxy-1-(propan-2-yl)cyclopentane-1-carbaldehyde, an aldol with no α-hydrogen. P is obtained: only its aldol can lose water.
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Coversintramolecular aldol condensationE1cBenolateretro-aldolconjugated enal
All parts of Question 7
- 7(a) Hofmann rearrangement; proof that it is intramolecular10 marks
- 7(b) Pentan-1-ol and pentan-2-ol by mass spectrometry5 marks
- 7(c) Photochemical ring opening of 8-methyl-1-decalone: Norrish Type II5 marks
- 7(d) Intramolecular aldol condensation of a dialdehyde10 marks