A deepseated carbodication rearrangement. Limited paths because of charge repulsion

The 1,5-manxyl dication undergoes a very specific skeletal rearrangement to give the 3,7-dimethylbicyclo[3.3.1]nona-3,7-diyl dication. The corresponding manxyl monocation is also labile but forms an apparent myriad of rearrangement products. This result is an indication that the dication rearrangement involves many fewer branching reactions.