Twistane derivatives

It has been pointed out that there is a torsional-angle (t) dependence of 3-SCS (cf. 40) (104). This angular dependence can be adequately described by multiplying the second term in eq. [15] by cos t (0° t 90°) for the appropriate fragment (104). By that treatment the 3-SCS values of methyl, hydroxy, chlorine, and nitro substituents in bomane (93,104,146,152-154) and twistane derivatives (104,155), which cannot be predicted by the simple eq. [15], become understandable. As expected, such an angular dependence does not exist if t is larger (90° < t < 180°) (156). 

The rearrangements of several twistane derivatives to adamantyl cations under the same conditions, on the other hand, appear to involve reversible, random carbonium ion formation, at least to a limited extent. Rearrangement of 2-twistanol-2-d (38) occurs with considerable intermolecular hydrogen scrambling (Eq. (15)) 40T Similar intermolecular rearrangements are observed when a 50 50 mixture of 1-adamantanol and l-adamantanol-3,5,7-d3 in S02 is treated with SbFs 40). 

Twistane derivatives (tricyclo [4.4.0.03>8 ] decanes) may be prepared in one step from the readily available ds-decal in-2,7-dione (Eq. (26)) 85, 86. ... 

The functional groups of the resulting l-acetoxy 5-twistanone may be selectively removed, enabling the preparation of a wide variety of 1- 86> 87> and 4- 8S) substituted twistanes by conventional techniques. Table 2 summarizes all twistane derivatives which have been reported. 

Synthesis and Chemistry of Polycyclic Hydrocarbons Related to Adamantane Table 2. Twistane derivatives... 

Table 5. Structures and optical rotations of twistane derivatives 3a, b and 34-50...

Paquette et al. stated the linear dependence of the rotational values at the Na line from the bridge lengths in twistane derivatives (Fig. 25). 

Related cyclizations are observed in certain bicyclic diketones, converting them into tricyclic aldols. Deslongchamps and coworkers discovered that c -bicyclo[4.4.0]decane-3,9-dione is the minor isomer in equilibrium with its intramolecular aldol, the twistane derivative (123 equation 145). The equilibrium could be shifted completely to the aldol by acetylation. 

Twistane derivatives were obtained by the reaction of a de-calindione with acetic anhydride, acetic acid, and boron trifluoride... 

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