(+)-Santonide, a sesquiterpenoid enol lactone derived from Artemisia

Abstract

The title compound, (1R,3aS,6aS,9S)-(+)-α,3a,7-trimethyl-5-oxo-1,4-ethanoperhydropentalene-1,8-carbolactone, C15H18O3, is the enol lactone of (−)-isosantonic acid, and a diastereomer of (+)-parasantonide. It is a skeletally rigid tetracyclic sesquiterpene derived from (−)-α-santonin, an anthelminthic obtained from various species of Artemisia. Molecules are linked by C—H...O close intermolecular contacts.