Ligulaverin A, a structurally novel sesquiterpenoid-derived metabolite possibly formed via a biological Diels–Alder reaction
Abstract
The crystal structure of Ligulaverin A 1, isolated from Ligularia veitchiana(Hemsl.) Greenm., reveals a novel carbocyclic skeleton which is likely to be derived from a hydroxymethacrylate ester of an eremophilane sesquiterpenoid via an intramolecular Diels–Alder reaction.