A Unifying Synthesis Approach to the C18-, C19-, and C20-Diterpenoid Alkaloids

The secondary metabolites that comprise the diterpenoid alkaloids are categorized into C-18, C-19, and C-20 families depending on the number of contiguous carbon atoms that constitute their central framework. Herein, we detail our efforts to prepare these molecules by chemical synthesis, including a photochemical approach, and ultimately a bioinspired strategy that has resulted in the development of a unifying synthesis of one C-18 (weisaconitine D), one C-19 (liljestrandinine), and three C-20 (cochlearenine, paniculamine, and N-ethyl-1a-hydroxy-17-veratroyldictyzine) natural products from a common intermediate.