Cyclooctene solvolysis

Transannular participation of n-bonds takes place in the solvolysis of esters of (Z)-cyclooct-3-enol to give bicyclic derivatives containing three-membered rings. Thus, acetolysis of 4-(4-bromophenylsulfonyloxy)cyclooctene followed by hydrolysis of the product mixture gave endo-and exo-bicyclo[5.1.0]octan-2-ol (1), in 39 and 13% yield, respectively. The predominant formation of the cntfo-bicyclooctanol is consistent with a concerted process. ... 

Sol 2. Tra/w-cyclooctene system is more stable than the c/s-isomer therefore, in this case the exo-isomer undergoes solvolysis at a much faster rate than the corresponding endo-isomer. 

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