Bisnoradamantane

Favorskii ring contractions of 1,3-dibromoadamantane-2,6-dione (55)121 12a) also provide synthetic approaches to bisnoradamantane derivatives as illustrated in Scheme 13. 

More recently, other approaches to this interesting ring system have also been developed. These are illustrated in Eqs. (41), 29< 13°) and (42) 131 As indicated, photochlorination of the parent hydrocarbon occurs only at the methylene positions 13°). The correspondence between free radical and car-bonium ion reactivities at the bridgehead positions of polycyclic hydrocarbons suggests that the bridgehead position of bisnoradamantane should also be highly unreactive in carbonium ion processes 1321. 

Like C2 bissecocubane (160) mentioned above, bisnoradamantane (164) (D2d) (Figure 20) is the next lower homolog of twistbrendane, and is specially interesting in that its D2(j symmetry has the origin in the intrinsic tricyclic system conceptually composed of two enantiomeric D2 twisted cyclohexanes interlocked together. 

Virtual long-range /(F,F) were nicely observed in F-bisnoradamantane. ... 

The structure and absolute configuration of vulgarone (32), an unusual sesquiterpene from Chrysanthemum vulgare, have been established from spectroscopic data, chemical reactions, and chiroptical comparison with (-1-)-chrysanthenone (both exhibit strong positive Cotton effects). The synthesis and absolute configuration of (-)-bisnoradamantan-2-one (33) have been reported. ... 

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