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The Benzene Ring as Dienophile in an Intramolecular [4 + 2] Cycloaddition: Degenerate Rearrangement of 7,8‐Benzobicyclo[4.2.2]deca‐2,4,7,9‐tetraene
Author(s) -
Grimme Wolfram,
Grommes Thomas,
Roth Wolfgang R.,
Breuckmann Rolf
Publication year - 1992
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199208721
Subject(s) - benzene , cycloaddition , intramolecular force , intermolecular force , ring (chemistry) , chemistry , degenerate energy levels , bicyclic molecule , medicinal chemistry , stereochemistry , physics , molecule , organic chemistry , catalysis , quantum mechanics
A Gibbs free energy of activation of 41.1 kcal mol −1 at 35°C has been determined for the rate‐determining step 3 → 2 of the rearrangement 3 → 1 (R = Me). This value is about 20 kcal mol −1 higher than that for the rearrangement of the parent compound, bicyclo[4.2.2]decatetraene. At 230°C, 1 and 3 are in dynamic equilibrium; an intermolecular [4 + 2] cycloaddition has been postulated in which participation of a π bond of the benzene ring leads to compound 2 as intermediate.