Q6(f). Dimerisation of cyclopentadiene: endo rule by frontier orbitals
Identify the reaction and predict the products A and B based on FMO approach. Give suitable justification for which product is major: 2 cyclopentadiene, Δ → A + B. [Structure of cyclopentadiene given in the paper]
Answer in brief
Diels–Alder [4π + 2π] dimerisation. A = endo-dicyclopentadiene (major, kinetic product). B = exo-dicyclopentadiene (minor).
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CoversDiels–Alder reactiondicyclopentadieneendo ruleFMO theorysecondary orbital overlap
All parts of Question 6
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- 6(b) Ozonolysis of camphene, then Wolff–Kishner reduction4 marks
- 6(c) Reductive amination, then intramolecular aza-Michael addition4 marks
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- 6(e) Amidomercuration–demercuration of hex-1-ene in acetonitrile4 marks
- 6(f) Dimerisation of cyclopentadiene: endo rule by frontier orbitals4 marks
- 6(g) Two isomeric esters C₇H₁₄O₂ from ¹H NMR4 marks
- 6(h) Mass spectrum of 3-butyn-2-ol: the ion of m/z 554 marks
- 6(i) Acetone: solvent shift of the n → π* band4 marks
- 6(j) Butyrophenone: McLafferty rearrangement and α-cleavage4 marks