Structures and enol–enol tautomerism of glutinosasins A–D, four novel 8,14-seco-ent-kaurane diterpenoids from Isodon glutinosus, were elucidated via quantum chemical calculations. Notably, glutinosasin D selectively inhibited SW480 tumor cells.
Two unprecedented diterpene heterodimers, isoxerophilins A and B (1 and 2), were isolated from Isodon xerophilus. A bioinspired semisynthesis of ten isoxerophilin analogues was accomplished. Compound 12 exhibited obvious latent tumor immunotherapy activity.
Three new ent-kaurane diterpenoids, isodosins E–G (1–3), along with 20 known ones (4–23), were obtained from the aerial parts of Isodon serra (Maxim.) Hara.
This review highlights how radical retrosynthesis, leveraging modern methods developed in recent years, enables strategic bond disconnection in the synthesis of complex terpenoid natural products.
This review summarizes the structural diversity, bioactivities, and biomimetic synthesis of [2 + 2]-type cyclobutane natural products, along with discussion of their biosynthesis, stereochemical analysis, racemic occurrence, and biomimetic synthesis.