- The Influence of Intramolecular Dynamics on Branching Ratios in Thermal Rearrangements
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1- and 2-phenylbicyclohex-2-enes-5-d undergo thermal rearrangement to give products, differing only in the location of the deuterium, in ratio of about 9:1, but with identical activation enthalphies.Similarly, opticallly active trans-2-methyl-1-(trans-2-phenylethenyl)cyclopropane is found to rearrange to enantiomeric methylphenylcyclopentenes that are formed in a 5.9:1 ratio but with virtually identicyl activation enthalphies.Barring repeated coincidence, these results do not seem to be explicable within the framework of statistical theories of unimolecular kinetics such as RRKM theory, transition state theory, and variational transition state theory.The possible influence of dynamic effects in these and other unimolecular reactions is discussed.
- Newmann-Evans, Richard H.,Simon, Reyna J.,Carpenter, B. K.
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p. 695 - 711
(2007/10/02)
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- Zur Photochemie des cis-1,3-Divinylcyclobutans
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The title compound 7 is obtained by ozonolysis of bicyclohex-2-ene (5) and Wittig reaction of the dialdehyde 6.There was no intramolecular photo-cycloaddition observed by irradiation of 7 but rearrangement to cis- and trans-allylvinylcyclopropanes 10 and 11.With the esters 12 - 14 the light energy is wasted in cis-trans-isomerisations.In comparison, the cis-1,3-cyclopentane derivatives 16 and 17 give some cycloaddition.
- Trautmann, Walter,Musso, Hans
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p. 982 - 989
(2007/10/02)
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