Crystal structures of 3β,19-dihydroxyandrost-5-en-17-one, 5, and its monohydrate, [(5).H 2 O]: 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).H ₂ O]], are reported. The monohydrate, isolated from a solution of 5 in 50% aqueous methanol, recrystallizes in the orthorhombic space group, P2 ₁ 2 ₁ 2 ₁ , while that of the anhydrous compound, isolated from solutions of THF, Me ₂ CO, EtOAc or dry MeOH, recrystallizes in the monoclinic space group, P2 ₁ . Apart from the different orientation of the 3-HO group, the conformations of the steroid molecules in 5 and [(5).H ₂ O]: are similar. The two-dimensional structure of 5 consists of sheets of molecules formed from strong classical O3-H3⋯O19 _(OH) and O19-H19···O3 _(OH) , 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 _(one) 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).H ₂ O]], each steroid molecule is directly connected to another by a O19-H19⋯O3 _(OH) 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).H ₂ O], we report on a survey of the crystal structures of related di- and tri- hydroxy-17-one derivatives as well as solvated compounds.
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