Biomimetic Skeleton Conversion from Tiglianes into Three Euphorbia Diterpenoid Skeletons via Regioselective Cyclopropane Ring-Opening

Structurally complex Euphorbia diterpenoids represent a synthetic challenge. Here, we report a divergent strategy that biomimetically converts abundant tiglianes into three Euphorbia skeletons via regioselective cyclopropane ring-opening. The high utility of this approach was demonstrated in the semisynthesis of two rhamnofolane-type natural products, langduin A (4) and fischerianin A (5), via a single transformation. This work provides not only rapid access to these diverse diterpenoid frameworks but also chemical evidence of their potential biosynthetic relationship.