Total Synthesis of Jatrophane Diterpenes from Euphorbia characias

The enantioselective total synthesis of the jatrophane diterpene (-)-15-O-acetyl-3-O-propionylcharaciol is described. Starting from an advanced cyclopentane building block, a B-alkyl Suzuki-Miyaura cross-coupling and carbonyl addition were utilized to assemble a fully functionalized triene, and a ring-closing metathesis was then employed to construct the rigid 12-membered ring. Twenty-five years after the original report on the isolation of the natural product, our total synthesis unambiguously corroborates the original tentative structural assignment.