COMPETITIVE REARRANGEMENTS .1. NEOPENTYLIC VERSUS SKELETAL BICYCLO[2.2.2]OCTANE -] BICYCLO[3.2.1]OCTANE REARRANGEMENTS

Generation of a carbenium ion common to two systems which are able to undergo either a skeletal bicyclo[2.2.2]octane --> bicyclo[3.2.1]octane rearrangement or a neopentylic rearrangement conducts only to the latter reaction. Thus, 8-carbomethoxy-7-t-butyl-dibenzobicyclo[2.2.2]octatriene (15) reacts with strong acids or bromine, yielding neopentyl rearranged products 17, respectively 21. Reaction mechanisms are proposed.