Superelectrophilic Nonclassical Carbocations.

The chemistry of dicationic and tricationic 2-norbornyl cations has been studied. A series of N -heterocyclic functionalized norborneol substrates were prepared and ionization of these compounds in superacid provided superelectrophilic species. These highly charged 2-norbornyl cations were found to react with arene nucleophiles in high yields and stereoselectivity. Density functional theory computational studies suggest that increasing positive charge on the structures tends to enhance the degree of nonclassical (or 3-center-2-electron) bonding through separation of the cationic charges.