Diosgenin-3,6-dione: second polymorph in space group P2(1)2(1)2(1).

The title steroid, [(25R)-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 P2(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.