An ent-kaurane diterpenoid from Isodon japonica var. glaucocalyx

The title compound, 14β-acetoxy-7α-hydroxy-ent-kaur-16-ene-3,15-dione or glaucocalyxin B, C22H30O5, 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 molecules 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, molecules are linked by intermolecular O—H...O hydrogen bonds.

Abstract licence: CC BY

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