Syntheses Substitutions and Rearrangements Involving Neighboring Group Participation of Dihetero-tricyclodecanes

Syntheses Substitutions and Rearrangements Involving Neighboring Group Participation of Dihetero-tricyclodecanes 

In the series of dihetero-tricyclodecanes, substitutions and rearrangements involving neighboring group participation of heteroatoms (onium ions) especially of oxygen (oxonium ions) sulfur (episulfonium ions, thiiranium ions) and nitrogen (ammonium ions, aziridinium ions) as well as in one case also of selenium (epi-selenium ions), were studied on adamantanes (G1), isotwistanes (G 2), twistanes (G 2) and homotwistbrendanes (G 4). 

According to the possible conHgurations of the leaving groups, syn or anti to the hetereoatoms, the starting materials may be classified by the following three groups  

Depending on the number of leaving groups or substituents, resp., the listing in Table 1 follows for the starting materials. 

Starting from the above compounds the following substitutions without and with skeletal rearrangements are possible. Intramolecular nucleophilic attack of the heteroatom X(2) at the R -substituted carbon atom of adamantanes G 36 as well as of isotwistanes G 37 leads to the same onium ion G 38. A priori, an external nucleophile has the three possibilities A, B and for an attack at a carbon atom. Attack A yields R -adamantanes G 39 (substitution under retention), attack B leads to -isotwistanes G 40 (substitution under skeletal rearrangement). 

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