The cover picture depicts in the colors of Princeton University two interpenetrating tetrahedra which are nonsuperposable mirror images of each other. According to one of the measures of chirality discussed by Mislow et al. on p. 989ff., these tetrahedra have attained the highest possible degree of asymmetry. Classical asymmetric shapes in organic chemistry result from the tetrdhedral arrangement of four different atoms around a central carbon atom, as illustrated by the ball-and-stick models of the enantiomers above the tetrahedra. The review by Mislow et al. offers a critical discussion of the measures of chirality as well as an up-to-date report on this field-and thus certainly provides food for thought, discussion, and Correspondence.
Review ArticlesThe unusual molecular structures and rr-electron systems of radialenes are as much a challenge for preparative chemists as for theoreticians. Two proven methods of synthesis that afford this class of compounds with parent compounds 1-4 are olefin-forming reactions at an existing cycloalkane skeleton and the thermal and metal-induced cyclooligomerization of [n]