Figure 2.

Raloxifene illustrates the quinone prediction method. Various resonance structures are considered in turn. For each structure, all paths between each pair of atoms are examined. Each atom pair is tested for compatibility with several predefined endpoint structures. A valid path is indicated by red bonds on the upper left. For this path, both endpoints are hydroxyls, in purple, which form a long-range quinone in a one-step, two-electron oxidation when the single and double bonds swap, as indicated by the arrows. Two-step quinone formations are also predicted by our method, such as that formed by hydroxylation followed by oxidation to form the lower right structure.