Twistbrendane

The rotational strengths of the twistbrendane 44, brexane 45 and of the cubane derivatives 46-48 also are smaller than those of twistane and 2,7-twistadiene. The circular dichroisms of the twistanones and twistanediones have been investigated (Table 6). 

The optical rotation values [o ]d 3b, 44, 45, 47-49) significantly decrease in the series twistane (s3), twistbrendane 44 and brexane 45. This can be interpreted in terms of helicity as follows Whereas the twistane molecule 3 contains five 6-membered rings in the twist conformation of equal helicity, in the case of brendane 44 there are only three 6-membered and two less twisted 5-membered rings brexane 45 only contains two 6-membered and three 5-membered rings. 

Figure 18. Stereochemical correlation between optically active twistane and twistbrendane.

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. 

Tritwistane (141) of D3 symmetry is one of the most interesting compounds in the family of triblattanes. As D3 trishomocubane (138) can be seen to be composed of three interlocked C3 twistbrendanes of same chirality, three D2 twistane moieties of same chirality interlock together to form tritwistane, reflecting its D3 symmetry. 

In accordance to the known twistbrendane (G tricyclo(5.3.0.0 ]decanes will be called homotwistbrendanes. 

The optically active endo-bicyclo-octene aldehyde (800), prepared by standard reactions from (798) via (799), is converted on u.v. irradiation into the cyclic ether (801) which can be reductively cleaved regiospeciGcally with LiAlH4 in JV-methylmorpholine to the alcohol (802). Net reduction of the alcohol (802) was achieved by the standard sequence (802)- (803)- (804). The final hydrocarbon product, (+)-twistbrendane (804), is in effect a nortwistane chiroptical data confirms (804) to be the enantiomer of the previously prepared (—)-twistbrendane. ... 

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