9a-Hy-droxy-3,8a-dimethyl-5-methyl-ene-4,4a,5,6,9,9a-hexa-hydro-naphtho-[2,3-b]furan-2(8aH)-one.

The title compound, C(15)H(18)O(3), was isolated from Lacta-rius piperatus (Fr.) S. F. Gary collected from the Kunming area in Yunnan province, China. The central cyclo-hexyl ring adopts a chair conformation, while the furan-one ring is close to planar (r.m.s. deviation = 0.0174 Å). The remaining methyl-ene cyclo-hexene ring has a flattened chair conformation. In the crystal, mol-ecules are linked via inter-molecular O-H⋯O and C-H⋯O hydrogen bonds into zigzag chains along the a axis.