(.+-.)-Schefflone: A Trimeric Monoterpenoid from the Root Bark of Uvaria scheffleri

The trimeric monoterpene and mildly mosquito larvicidal agent, (±)-schefflone, that is an apparent derivative of the antiparasitic aromatic monoterpene espintanol, was isolated from the antimalarial extracts of the root bark of Uvaria scheffleri, together with espintanol. Structural determination of (±)-schefflone was achieved from spectroscopic data and confirmed by single-crystal X-ray diffraction analysis. (±)-Schefflone can be considered a product of a non-enzymatic Diels–Alder-type cycloaddition reaction of the quinonemethide derivative of espintanol as the diene and dienophile.