Cyclophanes, XLI. Cyclophanes as Precursors for Saturated and Unsaturated Cage Hydrocarbons – the Catalytic Hydrogenation of [2.2]Paracyclophane
✍ Scribed by Hopf, Henning ;Savinsky, Rainer ;Jones, Peter G. ;Dix, Ina ;Ahrens, Birte
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 583 KB
- Volume
- 1997
- Category
- Article
- ISSN
- 0947-3440
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✦ Synopsis
Abstract
The catalytic hydrogenation of [2.2]paracyclophane 1 has been reinvestigated with the following results: a) Best yields (95%) of the perhydrocyclophane 3 are obtained when 1 is hydrogenated over ruthenium on charcoal in ethanol at 200°C and 300 atm in the presence of lithium hydroxide; b) hydrogenation of 1 in ethyl acetate/acetic acid over platinum at room temperature and normal pressure leads to the monoene 7 and one diene, to which we assign structure 11 since dichlorocyclopropanation converts it to the bis‐adduct 12, whose structure was determined by X‐ray structural analysis; c) when the tetraene 13 (prepared from 1 by Birch reduction) is hydrogenated over palladium on charcoal in petroleum ether, the triene 14 is obtained in addition to the dienes 4 and 11. Again, dichlorocyclopropanation followed by X‐ray structural analysis of the resulting tris‐adduct 17 was employed for the structure determination of the hydrocarbon precursor. The strain energies of the anti‐Bredt hydrocarbons 11 and 17 have been calculated by molecular mechanics calculations.