Dihetero-tricyclodecanes

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) . 

This review summarizes the results on dihetero-tricyclodecanes of the types G1 -G 5 known at present with particular emphasis on the synthesis of compounds from suitable 9-heterobicyclo[3.3,l ]- and 9-heterobicyclo[4.2.1 Jnonanes as well as by molecular rearrangements of dihetero-tricyclodecanes involving neighboring group participation. Furthermore spectral data are discussed mainly in connection with structural assignments. 

In principle two different synthetic approaches may lead to dihetero-tricyclodecanes of the types G 1-G 5 starting either from suitably functionalized 9-heterobicyclo-... 

Syntheses 9-Heterobicyclo[3.3.1 Jnonanes or 9-Heterobicyclo[4.2.1]-nonanes 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). 

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-... 

Conversions within the dihetero-tricyclodecane-series on the basis of which the same or another skeleton can be assigned to the involved compounds have already been described in the Sections 2., 3. and 4. 

Between approx. 1200 and 800 cm all dihetero-tricyclodecanes show marked sharp absorption bands. Comparing, e.g. the spectra of unsubstituted skeletal isomers, already gives good hints for the assignment of a certain structure type because compounds of higher symmetry exhibit less absorption bands than those of lower syih-metry [e.g. 2,7-dioxa-twistane 212) and 2,7-dioxa-isotwistane 128), resp.]. 

For tricyclo[4.3.1.0 ]decane the following trivial names were introduced in the literature isoadamantane (1968) protoadamantane (1968) isotwistane (1969) and 2(3 - 4)abeo-adamantane (1970) In the present review the name isotwistane will be applied, which until now is exclusively used to describe such 2,7-dihetero-tricyclodecanes. However, one should pay attention to the fact that since 1972 the trivial name iso-twistane is also applied for tricyclo[4.3.1.0 )decanes. 

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