Benzonorbomenyl cations

The cyclopropane ring in both epimers occupies the same position with respect to the departing group both epimers form a stable bisected cyclopropylcarbinyl cation. The exo endo rate ratio can reflect the contribution ratio of steric factors on the formation of the unsubstituted 2-benzonorbomenyl cation out of the two epimers. The hydrolysis of compounds 269 and 270 has resulted in an exo endo rate ratio of 12 and agrees fairly well with the previous value. A comparison of these data with the value of 15000 for the unsubstituted compounds clearly shows the steric and electrostatic effects to have a low value for secondary systems and in the absence of the ring 7i-participation the exo-isomer solvolyzes faster than its endo epimer only 2- to 10-fold. 

A similar effect is observed for the rearrangement of 2-benzonorbomenyl cations (29a,... 

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See also in sourсe #XX -- [ ]

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