Pepluanol A (1) and pepluacetal (2) belong to a structurally unique class of pepluanol-type Euphorbia diterpenoids, exhibiting immunosuppressive activity via targeting Kv1.3 channels. Herein, we report a divergent synthetic strategy that enables efficient and concise total syntheses of both 1 and 2 from a common advanced intermediate. The synthesis of pepluanol A (1) features an intramolecular Diels-Alder reaction to accomplish the 4 + 2 type cycloaddition for framework construction, whereas the synthesis of pepluacetal (2) is centered on a photoinduced intramolecular 2 + 2 cycloaddition as the key step. Both routes proceed with high stereoselectivity and synthetic efficiency. Further biological evaluation revealed that these diterpenoid natural products and derivatives possess antipulmonary fibrosis activity.
Qiu et al. (Tue,) studied this question.