Excursion to the World of Heptacyclic Compounds Made of Azulenes and Acetylenedicarboxylates |
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| Authors: | Yi Chen Erja Lehto Peter Uebelhart Anthony Linden Hans‐Jürgen Hansen |
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| Affiliation: | Institut für Chemie der Universit?t Zürich, Winterthurerstrasse 190, CH‐8057 Zürich |
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| Abstract: | Azulenes and acetylenedicarboxylates react under acid catalysis (Brønsted or Lewis) and form (2aRS,8aSR)‐2a,8a‐dihydrocyclopentacd]azulene‐1,2‐dicarboxylates as intermediate products, which then dimerize by central bond‐formation between C(2a1) and C(2′a1) and various peripheral C,C′‐atoms of the dihydroazulene fragments, depending on the substituents present. The reactions are often accompanied by the formation of side‐products, such as 2‐(azulen‐1‐yl)fumarates and ‐maleates and others caused by H‐shifts of the primary intermediates. H‐Shifts between the two tetrahydrocyclopentacd]azulene parts of the heptacyclic structures were also found. |
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| Keywords: | Azulenes Acetylenedicarboxylates |
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