A Unifying Synthesis Approach to the C(18)-, C(19)-, and C(20)-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-1α-hydroxy-17-veratroyldictyzine) natural products from a common intermediate.