Figure 1.Synthetic routes to catenanes. (a) Statistical; f and g are complementary functions that react to close the ring. (b) Statistical, using a rotaxane intermediate; f and g are complementary functions that react to anchor the stoppers; i and h are complementary functions that react to form the second, interlocked ring. (c) Directed. (d) Transition-metal-templated; the thick ring portions represent the coordination sites, and the black disk is the metal; f and g are complementary functions that react to close the second, interlocked ring. (e) Templated by aromatic p-stacking interactions; the open rectangles are electron-rich, and the filled rectangles are electron-poor, aromatic groups; f and g are complementary functions that react to form the electron-deficient macrocycle.
