Dihetero-homotwistbrendanes

Restriction among the great number of possible dihetero-tricyclodecanes to such with a carbocyclic 8-membered ring (cyclooctane) as basic skeleton, which is crosswise bridged by two heteroatoms, and restriction to 5-, 6- and 7-membered heterocyclic rings, isomeric dihetero-tricyclodecanes of the following five different stmctural types are possible 2,6-dihetero-adamantane (G 7 ) 2,7-dihetero-isotwistane (G 2,7-dihetero-twistane (G S) 2,8-dihetero-homotwistbrendane (G 4) and 2,6-dihetero-tricyclo[3.3.2.0 Jdecane (G 5) . 

Dihetero-homotwistbrendanes (G 4) can be prepared from isotwistanes with a suitable leaving group R—C(10) by rearrangement involving neighboring group participation of Y(7) (see 3.4.3.). However, homotwistbrendanes with X(2) = O, Y(8) = 0 are the only compounds of this stmctural type known so far. 

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). 

Starting from dihetero-tricyclodecanes described in the Sections 2. and 3. of the types of adamantane G1), isotwistane (G 2), twistane (G 3) and homotwistbrendane (G 4), which in their turn were prepared either by cyclization of suitable 9-heterobicyclo-... 

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