Cope rearrangement of the endo-5-vinylbicyclo[2.2.1]hept-2-ene (endo-5-vinylnorborn-2-ene) radical cation to the cis-bicyclo[4.3.0]nona-3,7-diene (cis-3a,4,7,7a-tetrahydroindene) radical cation at 100–150 K. A matrix–isolation ESR study
Abstract
Radical cation ‘fingerprinting’ by ESR spectroscopy reveals that the radiolytic oxidation of endo-5-vinylbicyclo[2.2.1]hept-2-ene 2 leads to the formation of the cis-bicyclo[4.3.0]nona-3,7-diene radical cation 3·+ by a [3,3]sigmatropic shift at 100–150 K, whereas the neutral Cope rearrangement from 2 to 3 only occurs at 400–440 K.