title: 11,20-Dihy-droxy-3-oxopregna-1,4-dien-21-oic acid monohydrate.
abstract: The title compound, C(21)H(28)O(5)·H(2)O, is the hydrate of a steroid derivative and was obtained by degradation of solid prednisolone sodium phosphate. The six C atoms in ring A are nearly co-planar with a mean deviation of 0.015 Å. Rings B and C are both in chair conformations, while ring D has an envelope form. In the crystal, inter-molecular O-H⋯O hydrogen-bonding inter-actions occur between the hy-droxy groups, carbonyl O atoms and solvent water mol-ecules, resulting in an overall three-dimensional structure.
authors.affiliation: School of Pharmaceutical Sciences, Research Center of Basic Medical Sciences, Tianjin Medical University, Tianjin 300070, People's Republic of China.
authors.forename: Zhanqiang
authors.initials: Z
authors.lastname: Guo
authors.forename: Shengan
authors.initials: S
authors.lastname: Tang
authors.forename: Hongquan
authors.initials: H
authors.lastname: Duan