Here are a few of the bridged polycyclics we looked at at the end of Chapter 5. First, camphor, in which the basic ring skeleton is a bicyclo[2.2.1]heptane:
Next the "In" isomer of bicyclo[4.4.4]tetradecane, having an inverted bridgehead, so that the hydrogen is directed into the interior cavity of the molecule. Most molecules do not have a large enough "hole" in the middle to accomodate a substituent.
Adamantane, C10H16, has the same arrangement of carbon atoms as diamond. Although it was first synthesized, laboriously, by V. Prelog, its chemistry was not explored until Paul Schleyer discovered that it could be made by rearranging almost any other tricyclic hydrocarbon having at least ten carbons.
Finally, here's one not described in Chapter 5; we will meet it again in Chapter 12. C60, buckminsterfullerene, popularly known as buckyball. The pattern of 5- and 6-rings is exactly that found on the surface of a standard soccer ball. Recently, Martin Saunders of Yale found that when it is prepared in an atmosphere of He, helium atoms can be trapped inside!