Alkanes polycyclic—

In the other method, the ending -ane is changed to -ene or -yne to indicate the presence of a double or triple bond. This is used for alkanes and mono- and polycyclic alkane parent hydrides. In alkanes and cycloalkanes, the change of the -ane ending to -ene or -yne indicates the presence of one double or triple bond. Multiplicative prefixes di-, tri-, tetra-, etc. are used to signal the multiplicity of unsaturated bonds. Locants placed immediately in front of the endings -ene and -yne are used as needed. 

Cyclic amido-A3-iodane prepared from 85 in one step can be used as a direct amidating reagent toward polycyclic alkanes under radical conditions [Eq. (83)] [155]. 

Scheme 2. A selection of PTC radical halogenations with linear, cyclic, and polycyclic alkanes.

For a more comprehensive list of unusual polycyclic alkanes (including windowpane, davidane, catenane, propellane, and many others), see Organic Chemistry The Name Game by Alex Nickon and Ernest Silversmith, Pergamon Press, 1987. 

Ensminger A., Albrecht P., Ourisson G., and Tissot B. (1977) Evolution of polycyclic alkanes under the effect of burial (Early Toarcian shales, Paris Basin), la Advances in Organic Geochemistry 1975 (eds. R. Campos and J. Goni). ENADIMSA, Madrid, pp. 45-52. 

More polycyclic alkanes have been treated by INS spectroscopy. The spectrum of of adamantane (tricyclo[3.3.1.1 ]decane, CioHie) is shown in Fig. 4.6. Norbomane and some of its mono- and dimethyl derivatives (see Fig. 8.5 for the structures) were extensively studied and force fields developed using the Wilson GF matrix method [17—19]. Given the low symmetry and relatively large number of atoms present, this was a tour de force of spectroscopy. 

This is illustrated by the application of dioxiranes to polycyclic alkanes possessing a sufficiently rigid framework, such as the 2,4-didehydro adamantane case. For this substrate the reaction with DDO proceeds with 82% conversion during 12 h, yielding the expected 2,4-didehydroadamantan-7-ol, but also the precious 2,4-didehydroadamantan-lO-one in comparable yield (eq 35). The ketone derives from competitive dioxirane attack at the methylene positions a to the cyclopropyl moiety the latter is encompassed in the rigid 2,4-didehydroadamantane framework to lay constrained into a bisected orientation relative to the neighboring methylene C-H bonds. 

Amidobenziodoxoles Amidobenziodoxoles 128-132 are readily synthesized in one step by treatment of the triflate 108 with an appropriate amide, RNH2 (Scheme 2.45) [295]. All five adducts (128-132) were isolated as thermally stable, white, non-hygroscopic, microcrystalUne solids. Amidobenziodoxoles can be used as amidating reagents toward polycyclic alkanes under radical conditions [295]. 

Amidobenziodoxoles (Section 2.1.8.1.6) have been used as the amidating reagents toward polycyclic alkanes under radical conditions. For example, reagent 515 reacts with adamantane in chlorobenzene at 100-105 °C in the presence of a catalytic amount of benzoyl peroxide to afford 1-amidoadamantane 516 in moderate yield (Scheme 3.204) [583]. 

The majority of the polycyclic alkanes in nature derive from the terpenoid family (C5 isoprene units) with the principal structural variations of six and five fused rings, formed by cyclization of the polyene open terpenoids (Ciq, C15, C20, C25 - up to C4.0). 

For the solid, mostly polycyclic alkanes. X-ray structural analysis can be employed for pure compounds and combined with either very accurate elemental analysis or MS study to produce very important information. 

Bicyclic and higher polycyclic alkanes exhibit much more complex MS fragmentation. Budzikiewic and coworkers caution that great prudence, even in the use of published spectra, must be exercised for comparison and identification purposes of polycyclic alkanes. As examples they show the mass spectrum of cis-hydrindane, in which m/e 95,96,81 are major fragments which can be assigned only in retrospect to the structure once known. However, given only the MS it will be impossible to reconstruct the structure of the molecule. 

As an analytical tool, NMR spectroscopy of or is best used for single compound structure determination. Despite the introduction of the FT multispectra unit, the sample size is only in the mg range. With the continued development of high-resolution NMR, more and more complex structures could be elucidated" ". The elucidation of the stereostructure of the 5a,14a androstane by 2D-NMR data is an excellent example of the study of a complex polycyclic alkane of the steroid family . Croasmun and Carlson review the possible use of the various 2D-NMR methods showing spin coupling, NOE... 

The chemical shifts of several other polycyclic alkanes are collected in Table 8. The most recent example is tricyclo[4.2.0.0. ]octane, in which three-, four- and five-membered rings are fused. ... 

The CNMR data for selected substituted bicyclic and polycyclic alkanes are listed in Table 9. Noteworthy is the upheld shift for the quaternary carbon atom of the tert-buiy group in 24, which can be attributed to the special bonding character in the tetrahedrane... 

TABLE 8. CNMR chemical shifts of tricyclic and polycyclic alkanes... 

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