title: 15α,20β-Dihydr-oxy-6β-meth-oxy-6,7-seco-6,20-ep-oxy-1,7-olide-ent-kaur-16-ene.
abstract: The title compound, C(21)H(30)O(6), a natural ent-kaurane diterpenoid, was obtained from the medicinal plant Isodon serra. The five rings in the mol-ecule exhibit the expected cis and trans junctions. The three six-membered rings adopt chair, twist-boat and boat conformations, while two five-membered rings adopt envelope conformations. There are two mol-ecules in the asymmetric unit, related by a non-crystallographic twofold screw axis; the main difference is in the different degrees of distortion of ring B. In the crystal, the mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds, forming chains along the b axis.
authors.affiliation: School of Pharmacy, Xinxiang Medical University, Xinxiang, Henan 453003, People's Republic of China.
authors.forename: Fu-Lin
authors.initials: FL
authors.lastname: Yan
authors.forename: He-Qin
authors.initials: HQ
authors.lastname: Zhan
authors.forename: Chuang
authors.initials: C
authors.lastname: Feng
authors.forename: Xue-Mei
authors.initials: XM
authors.lastname: Di