Special Topic Adamantanes in Materials and Biology

PROBLEM 5.29 Why is tricyclo[1.1.1.0 ]pentane unusual (Fig. 5.64) Would you expect it to be especially stable or unstable with respect to its cousin bicy-clo[l.l.l]pentane Why  

Wiberg s molecule was synthesized in a chemistry laboratory, and probably ( ) does not occur in Nature. Nature is by no means played out as a source of fascinating polycyclic molecules, however. For example, in 2003 Sanae Furuya and Shiro Terashima reported the synthesis of optically active tricycloillinone, a molecule isolated from the wood of lllicium tashiori (Fig. 5.65). This molecule enhances the activity of choline acetyltransferase, an agent that catalyzes the synthesis of acetylcholine. Why should we care about tricycloillinone A form of senile dementia (Alzheimer s disease) is associated with reduced levels of acetylcholine, and a molecule that might be useful in increasing levels of acetylcholine FIGURE 5.65 Tricycloillinone. is of obvious importance to all of us. 

The dots are carbons every other vertex is a boron. There is a hydrogen atom at every vertex 

As you ve seen in this chapter, ring compounds can be straightforward (cyclopentane, p. 190, is a nice example), moderately complex (the mobile cyclohexanes, p. 197), or exotic ([l.l.ljpropellane, p. 216). Here is a compound that surely qualifies as exotic, if not downright weird. It is composed of two carbons (the dots) and ten borons (the other 10 vertices), and contains no fewer than 20 three-membered rings of carbons and borons. Why weird Count the bonds to carbon. There are six bonds emanating from the carbon Six bonds How can that be If you draw a carbon with five 

Consider constructing a polycyclic molecule by expanding a chair cyclohexane. First, connect three of the axial bonds to a cap consisting of three methylene (CH2) groups all connected to a single methine (CH) group. This process 

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