Nonclassical deltacyclyl cation

At this point we can conclude that the solvolysis of exo-deltaeyclyl brosylate 2 proceeds directly through a nonclassical deltacyclyl cation intermediate 13. ... 

The nonclassical nature of the deltacyclyl cation 13 was conBnned by NMR and by density functional methods. Deltacyclyl cation 13 is about 5.0 kcal/mol more stable tban the known nonclassical 2-norbomyl cation. 

The solvolysis of exo-8-deltacyclyl brosylate 2 proceeds directly to nonclassical deltacyclyl carbocation intermediate 13, whereas the e cfo-isomer first forms a classical carbocation 17, which either generates intermediate 13 or isomerizes by alkyl migrations involving nonclassical isodeltacyclyl cation 11. The special stability of the nonclassical cations compared with their classical counterparts seems to be the key of the process. 

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