The rearrangements of 4-substituted bicyclo[2.2.2]oct-5-en-2-yl radicals, generated from the corresponding Diels-Alder adducts with phenylseleno acrylates by radical-induced reductive deselenocarbonylations, give the 2-substituted bicyclo[3.2.1]oct-6-en-2-yl radicals with some substituents, e.g., alkoxy and phenyl, but not for silyloxymethyl or benzyl substituents. Theoretical calculations with DFT give the thermodynamics of these reactions and the origins of these processes.