Diosgenin-3,6-dione: second polymorph in space group P 2 1 2 1 2 1 .

The title steroid, [(25 R )-spirost-4-en-3,6-dione, C 27 H 38 O 4 ], is obtained by oxidation of diosgenin, using the Jones reagent (CrO 3 /H 2 SO 4 ). The crystal structure was previously reported in space group P 2 1 2 1 2 1 , but nonetheless with the wrong absolute configuration and omitting positions for H atoms [Rajnikant et al. (2000 ▸). Mol. Cryst. Liq. Cryst. Sci. Technol. Sect. C , 12 , 101-110]. The diffraction data set reported herein is for a second polymorph in the same space group, as evidenced by simulated powder patterns. Both forms are characterized by a similar ortho-rhom-bic unit cell, and a similar arrangement of the mol-ecules in the crystal structure. However, the conformation of the A / B rings in the steroid nucleus is slightly modified, leading to the observed polymorphism.