8.9- Dehydro-2-adamantyl-3,5-dinitrobenzoate

With the aim of studying a geometrically well-defined cyclopropylcarbinyl cation Baldwin and Foglesong (1968a) prepared the 8,9-dehydro-2-adamantyl 3,5-dinitrobenzoates [125 X = H, D or T]. The solvolysis of [125] in 60% aqueous acetone proceeded with considerable rate enhancement in comparison with 2-adamantyl tosylate. Scrambling of the label to the 8 and 9 positions in the solvolysis of [125 X = D] and [125 X = T] revealed a degenerate rearrangement (90) of the intermediate 8,9-dehydro-2-adamantyl cation [126]. 

Finally, several systems which are more commonly thought of as dehydroadamantyl or dehydrohomoadamantyl systems may also be considered as 2-bicyclo[4.1.0]heptyl derivatives. For the case of the 8,9-dehydro-2-adamantyl 3,5-dinitrobenzoate (85),... 

There is very good evidence that if the cyclopropyl group of a cyclo-propylcarbinyl derivative can interact with the developing cationic center in a bisected conformation a very large rate enhancement results, whereas if this conformation is prevented sterically, there is no rate enhancement. Thus on the basis of the rate of solvolysis of 8,9-dehydro-2-adamantyl 3,5-dinitrobenzoate in aqueous acetone it was estimated that the corresponding toluene-p-sulfonate (43) would undergo acetolysis about 8 powers of 10 faster than 2-adamantyl toluene-p-sulfonate (44). It was also esti-... 

Another adamantyl system which has recently been studied by Harris and coworkers is the endo-2,4-dehydro-5-homoadamantyl 3,5-dinitrobenzoate (86). The product from... 

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