Fulven-Dimere und -Trimere. Hinweis auf eine [6 + 4]-Cycloaddition von 6,6-Dimethylfulven
In contrast to earlier assumptions, thermal reaction of simple fulvenes 1a, b, c at 20°C gives Diels-Alder-dimers 2a, b, c in a relatively high yield. Whereas the dimers 2b and 2c equilibrate easily with the corresponding fulvenes at 60 °C, heating of the fulvene-dimer 2a produces an equilibrium 2a...
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| Main Authors: | , |
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| Format: | Article |
| Language: | deu |
| Published: |
Swiss Chemical Society
1981-10-01
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| Series: | CHIMIA |
| Online Access: | https://www.chimia.ch/chimia/article/view/9536 |
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| Summary: | In contrast to earlier assumptions, thermal reaction of simple fulvenes 1a, b, c at 20°C gives Diels-Alder-dimers 2a, b, c in a relatively high yield. Whereas the dimers 2b and 2c equilibrate easily with the corresponding fulvenes at 60 °C, heating of the fulvene-dimer 2a produces an equilibrium 2a ⇄ 3a. After heating of pure 6,6-dimethylfulvene (1c) for several months at 60°C, a trimeric product 6c is isolated with a 35 % yield (60 % with respect to reacted 1c). Formation of 6c may be explained by a thermodynamically controlled [6 + 4]-cycloaddition of 2 molecules of 1c, followed by a 1,5-H-shift as well as by Diels-Alder-reaction of 5c with a third fulvene molecule.
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| ISSN: | 0009-4293 2673-2424 |