A new eremophilanolide from Senecio sinuatus Gilib

From the hexane extracts of Senecio sinuatus roots, the new 3β‐angeloyloxy‐6β‐hydroxyeremophil‐1(10)‐en‐8β,12‐olide (3), along with the known compounds 3β‐angeloyloxy‐6β‐hydroxyeremophil‐1(10)‐ene (1), 3β‐senecioyloxy‐6β‐hydroxyeremophil‐1(10)‐ene (2), and 3β‐angeloyloxy‐6β,8α‐dihydroxyeremophil‐1(10)‐en‐8β,12‐olide (4), were isolated. Complete 1 H and 13 C NMR chemical shift assignments of 1–4 were achieved using one‐ and two‐dimensional NMR techniques, including gHMQC and gHMBC experiments. A Monte Carlo search, followed by B3LYP/6‐31G*DFT calculation, provided the theoretical conformations of the eremophilane rings, which were in agreement with results derived from 1 H 1 H NMR coupling constant analysis, and confirmed by NOESY experiments. Copyright © 2007 John Wiley & Sons, Ltd.