 By extension , any <unk> cation regardless of its origin is capable of undergoing a <unk> <unk> . There have been a large number of examples published where the requisite cation is arrived at by a variety of rearrangements . One such example involves the silver catalyzed cationic ring opening of <unk> <unk> <unk> . The silver salt facilitates loss of chloride via precipitation of insoluble silver chloride . 
