50895-59-5Relevant articles and documents
Diademane and Structurally Related Compounds, I. Preparation and Characteristic Reactions of Some Tris-?-homobenzene Hydrocarbons
Kaufmann, Dieter,Fick, Hans-Heinrich,Schallner, Otto,Spielmann, Werner,Meyer, Lueder-Ulrich,et al.
, p. 587 - 609 (2007/10/02)
Diademane (5) and 1,6-Homodiademane (6) are the first hydrocarbons with cis-tris-?-homobenzene skeletons.They were prepared by photoisomerization of the olefinic precursors 8 (snoutene) and 15 (4,5-homosnoutene), respectively.In an analogous reaction the bridged trans-tris-?-homobenzene 7 was formed from 17 (endo,exo-bishomobarrelene). 7 is more easily obtained from 17 by rhodium(I)-catalyzed isomerization or from exo,exo-bishomobarrelene 18 by thermal rearrangement.The unbridged 4 was prepared using a newly developed synthetic sequence starting from 1,3-cyclohexadiene.The thermal rearrangement of 5 and 6 to triquinancene (9) and 1,10-homotriquinancene (16) is very facile; the gas phase kinetic parameters (ln k (5) = 33.7 - 31600/RT and ln k (6) = 32.2 - 28300/RT, both first order) strongly corroborate, that these rearrangements are concerted ?2S + ?2S + ?2S> cycloreversions. -labelled 4 upon thermolysis yields a trans-bicyclonona-3,7-diene (31 22) with a 12C-labelling pattern, which proves its formation via a 3-step mechanism.The first step in this sequence most probably is a ?2S + ?2S + ?2S> cycloreversion with ln k = 30.8 - 42000/RT (first order).Only the bridged compound 7 does not follow the sample path, probably due to excessive ring strain in the transition state, and prefers a stepwise cycloreversion leading to 18 and at least 5 secondary products.
