Norbomene deuterium addition

Neither can the experimental results be explained by the assumption of a rapid equilibrium of classical ions imitating a nonclassical ion since in this case the distribution of deuterium between C and C must be equal. The addition of acetic acid can proceed through two mechanisms ionic addition via a nonclassical ion ( 50%) and simultaneous molecular exo-cis-addition ( 50%). Brown, however, showed that the addition of the acetoxy group when acetic acid acts on 7,7-di-methylnorbomene proceeds with the same stereospecificity (99.98 % of exo isomer) as in the reaction with norbomene i.e. simultaneous addition of acetic acid seem to be highly improbable. 

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