Acta Cryst. (2013). E69, o1087
[ doi:10.1107/S1600536813015729 ]
Abstract: The title compound, C17H20O5, an eremophilane sesquiternoid, was isolated from the roots of Ligularia lapathifolia. The molecule contains four fused rings of which the six-membered ring A adopts a half-chair conformation, the six-membered ring B adopts a chair conformation, the five-membered ring C is almost planar (r.m.s. deviation = 0.015 Å) and the five-membered ring D adopts an envelope conformation with the quaternary C atom as the flap. The methyl and the ethoxy groups adopt a syn conformation and the A/B ring junction is cis-fused. No directional intermolecular interactions could be identified in the crystal.
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