title: An ent-kaurane diterpenoid from Isodon japonica var. glaucocalyx.
abstract: The title compound, 14β-acet-oxy-7α-hydr-oxy-ent-kaur-16-ene-3,15-dione or glaucocalyxin B, C(22)H(30)O(5), a natural ent-kaurane diterpenoid, is composed of four rings with the expected cis and trans ring junctions. In the crystal structure, there are two mol-ecules in the asymmetric unit related by a noncrystallographic twofold screw axis, and ring A is disordered [ratio occupancies 0.829 (19):0.171 (19)], such that both chair and boat conformations are present, but with the boat conformation as the major component. In the crystal, mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds.
authors.forename: Su-Ping
authors.initials: SP
authors.lastname: Bai
authors.forename: Guo-Sheng
authors.initials: GS
authors.lastname: Luo
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Liu