Q10(b). Dimer of cyclopentadiene; a [1,3] shift of carbon with inversion
Write down the products in the following reactions and provide a suitable explanation: I. 2 × cyclopentadiene, room temp. → ?; II. deuterium-labelled bicyclic acetate, Δ → ? [structures given in the paper]
Answer in brief
I = endo-dicyclopentadiene, C₁₀H₁₂, the Diels–Alder dimer. II = exo-norborn-5-en-2-yl acetate with D exo on C-3, cis to the acetoxy group: a thermal [1,3] shift of carbon with inversion.
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CoversDiels–Alder dimerisationdicyclopentadieneendo rule[1,3]-sigmatropic shiftinversion at migrating carbon
All parts of Question 10
- 10(a) Structure from UV, IR, NMR and mass spectra: C₁₂H₁₄O₄10 marks
- 10(b) Dimer of cyclopentadiene; a [1,3] shift of carbon with inversion10 marks
- 10(c) Urea, amine and carbamate from benzoic acid (Curtius route)10 marks