- Does Cycloaddition between Pentafulvene and Cyclopentadiene Take Place?
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Reaction of a 1:1 mixture of cyclopentadiene (CPD) and pentafulvene (1a) at 20 deg C gives a complex mixture.The low-molecular-weight part mainly consists of pure and mixed dimers (ca. 73percent) besides corresponding trimers (ca. 20percent) and some corresponding oligomers according to GC/MS investigations (Fig.1).The 3 predominant 'mixed dimers'between CPD and 1a have been separated, and structures 4-6 (Scheme 3) are assigned according to 400- and 600-MHz 1H-NMR investigations.These results show that HOMO(CPD)-LUMO(fulvene) interactions are important in pentafulvene cycloadditions.Dimer 6 results from cycloaddition followed by -H shifts.
- Niggli, Urs,Neuenschwander, Markus
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p. 2199 - 2208
(2007/10/02)
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- anti--Dicyclopentadiene
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The synthesis of anti-tricyclo2,5>deca-3,7-diene (2) starting from the -cycloadduct 4a derived from cyclopentadiene and tropon is described.Compound 2 decomposes at 200 deg C yielding a mixture of cyclopentadiene (12), endo--dicyclopentadiene (13), anti-cis--dicyclopentadiene (14) and the cyclopentenyl-cyclopentadienes 15 and 16.The formation of a common diradical intermediate 11 in the decomposition of 2, 13 and 14 has been sought by means of the kinetic analyses of these reactions.
- Grimme, Wolfram,Schumachers, Lothar,Roth, Wolfgang R.,Breuckmann, Rolf
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p. 3197 - 3208
(2007/10/02)
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