Isolation and Structure of Three Bislactones, Eremopetasitenin B4 and Eremofarfugins F and G, from Ligularia przewalskii and Revision of the Structure of an Epoxy-lactone Isolated from Ligularia intermedia
Three bislactones belonging to the eremophilane type were isolated from Ligularia przewalskii (Asteraceae): an epoxylactone (eremopetasitenin B-4) identical to the previously isolated lactone, whose structure was revised in this work; a new enollactone (eremofarfugin F); and its diastereoisomer at C-11 (eremofarfugin G). This was identical to the reported lactone, whose stereochemistry was left undetermined. The stereochemistry along with the NMR data of this diastereoisomer was assigned in this study.