Four new compounds from Ligularia virgaurea: isolation of eremophilane and noreremophilane sesquiterpenoids and the absolute configuration of 2α-hydroxyeremophil-11-en-9-one by CD spectrum and DFT calculation

Four new compounds, rearranged noreremophilan-8,6-olide, rearranged dinoreremophilanone, epoxy γ-lactone, and 2α-hydroxyermophil-11-en-9-one, along with eremophilenolides related to ligularol and other known terpenoids, were isolated from Ligularia virgaurea (ligularol type) collected from the northern Sichuan Province of China. Three of the new compounds had degraded and unique structures. The absolute configuration of...