Adamantanes Noradamantanes

Protoadamantanone is a versatile intermediate for the synthesis of not only protoadamantane derivatives,but also 1,2- and 2,4-disubstituted adamantanes, ° 2-substituted noradamantanes," and 4(5)-substituted 4-homoprotoadamantanes. ... 

One other farily strained adamantoid molecule which has been found to be readily available via the rearrangement route is noradamantane (23). Brexane (24), a C9 tricyclic hydrocarbon, rearranges smoothly in the presence of A1C13 to the lower adamantane homologue, 23, in 75 % yield (Eq. (11)) 36 This rearrangement, however, is consistent with thermodynamic principles. (See Section 111. E and Scheme 8 for other preparations of this hydrocarbon). 

Similar symmetry problems confront the substitution reactions of other systems, e.g. noradamantane, homoadamantane and ethanoadamantane. Nor-adamantane, for example, may be brominated when treated with bromine under vigorous conditions but a difficult to separate mixture of bromides results72. At the present time, derivatives of noradamantane (see also Scheme 8), homoadamantane, and related systems are most readily obtained by more indirect methods as discussed in Section III. Bromination of ethanoadamantane (25) gives a single monobromide, however 38b). 

Protoadamantanone is a versatile intermediate for the synthesis of not only protoadamantane derivatives,but also 1,2- and 2,4-disubstituted adamantanes, 2-substituted noradamantanes, and 4(5)-substituted 4-homoprotoadamantanes. 4-Protoadamantanone has been prepared by the nitrous acid deamination of 2-amino-l-adamantanol (77%), by aprotic diazo-tization of endo-7-aminomethylbicyclo[3.3.1]nonan-3-one in benzene with an equivalent amount of acetic acid (67%), and by thermolysis of 1-adamantyl hypohalites followed by base-promoted cyclization of the resulting halo ketones (32-37%).In spite of low and erratic yields, the last reaction sequence has provided the most convenient route to the protoadamantanes, since the other two approaches require lengthy syntheses of the starting materials. 

The rearrangements of cage-like structures have been discussed in some detail in refs. 11 and 12, and can be divided into three main classes (i) homocubane to cubane (ii) adamantane to noradamantane and (iii) homoadamantane to twist-brendane and these are depicted (together with strain energy estimations from ref. 79) in Scheme 39. It can be seen that in each case rearrangement provides a system with... 

A series of chalcogen-containing adamantanes 141 have been prepared using the route shown in Scheme 39 <2001JOM(628)133> and the noradamantane 142 can be prepared in a similar way if (Cl2MeSi)2 is added as a reagent. 

Herzog U, Rheinwald G (2001) New chalcogen derivatives of silicon possessing adamantane and noradamantane structures. J Organomet Chem 628 133... 

Herzog U, Borrmann H (2003) Organosilicon chalcogenides with trisilane units -adamantanes and noradamantanes. J Organomet Chem 681 5... 

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