Crystal structures of 3β,19-dihydroxyandrost-5-en-17-one, 5, and its monohydrate, [(5).HO]: A survey of the structures of related di- and tri-substituted hydroxy derivatives and their solvated compounds.

The crystal structures of 3β,19-dihydroxyandrost-5-en-17-one, 5, and its monohydrate, [((5).HO]], are reported. The monohydrate, isolated from a solution of 5 in 50% aqueous methanol, recrystallizes in the orthorhombic space group, P222, while that of the anhydrous compound, isolated from solutions of THF, MeCO, EtOAc or dry MeOH, recrystallizes in the monoclinic space group, P2. Apart from the different orientation of the 3-HO group, the conformations of the steroid molecules in 5 and [(5).HO]: are similar. The two-dimensional structure of 5 consists of sheets of molecules formed from strong classical O3-H3⋯O19 and O19-H19···O3, augmented by weaker C-H⋯O hydrogen bonds. Noticeably the presence of the C19 hydroxyl group results in the replacement of the O3-H3⋯O17 hydrogen bonds as the strongest intermolecular interaction found in the stable polymorphs of the mono-hydroxylated compound, 3β-hydroxyandrost-5-en-17-one (dehydroepiandrosterone). An additional structural difference between 3β-hydroxyandrost-5-en-17-one and 3β,19-dihydroxyandrost-5-en-17-one is that the steroid molecules are most strongly linked head-to-tail in the former but head-to-middle fashion in the latter. In the three dimensional structure of [((5).HO]], each steroid molecule is directly connected to another by a O19-H19⋯O3 hydrogen bond and indirectly to two others via the water molecule. Each water molecule forms three hydrogen bonds, namely O3-H3⋯Ow, Ow-Hw1⋯O17 and Ow-Hw2⋯O19. As found for most hydrated steroids, the hydrate molecules have strong influences on the structure. In addition to the reporting of the crystal structures of 5 and [(5).HO], we report on a survey of the crystal structures of related di- and tri- hydroxy-17-one derivatives as well as solvated compounds.