Two new sesquiterpene lactones of eremophilane-type were isolated from Ligularia Fauriei (Fr.) Koidz., and their structures including absolute stereochemistry were shown to be 8β-hydroxyeremophil-7(11)-ene-12,8α;14β,6α-diolide (1) and eremophil-7(11)-ene-12,8α;14β,6α-diolide (2), respectively. The isolation of the two known lactones, 6β,8β-dihydroxyeremophil-7(11)-en-12,8α-olide (3) and 6β-hydroxyeremophil-7(11)-en-12,8α-olide (4), is also described. The photosensitized autoxidation of the known furanoeremophilan-14β,6α-olide (5) gave 1 and 8β-methoxyeremophil-7(11)-ene-12,8α;14β,6α-diolide (18).
Structural studies of four new sesquiterpenes, 3β-angeloyloxy-6β-(3-methylbutanoyloxy)- and 3β,6β-bis(angeloyloxy)furanoeremophilan-14-als and 3β-angeloyloxy-6β-(3-methylbutanoyloxy)- and 3β-angeloyloxy-6β-(3-methylpentanoyloxy)furanoeremophilan-14-oic acids, together with 3β,6β-bis(angeloyloxy)furanoeremophilan- 14-oic acid from Syneilesis palmata (Thunb.) Maxim, are described.
Five new furanoeremophilane derivatives, I, II, III, IV, and V, have been isolated from Farfugium japonicum Kitamura, and their structures have been determined. Conformations of some furanoeremophilane derivatives are discussed.
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