Taxol® (Figure 7.1; 1), a diterpene originally isolated from the American Pacific yew Taxus brevifolia,1 has emerged as one of the most effective chemotherapeutic agents for the treatment of breast and ovarian cancers.2 The compound is also in development for non-small-cell lung cancers,3 and head and neck cancers.4 Taxol’s development has included periods of both unusual languor and speed.5 It acts by blocking the normal depolymerization of microtubules, a process that is crucial for a number of cellular functions including mitosis.6 The elucidation of this unique mechanism by Horwitz’s group in the early 1980s spurred the drug’s development.7