6b -Chloro-5a-hydroxy-20-oxopregnan- 3b -yl acetate Rui M. A. Pinto, a Jorge A. R. Salvador, a Jose ´ A. Paixa ˜o, b * Ana Matos Beja b and Manuela Ramos Silva b a Laborato ´rio de Quı ´mica Farmace ˆutica, Faculdade de Farma ´cia, Universidade de Coimbra, P-3000-295 Coimbra, Portugal, and b CEMDRX, Departamento de Fı ´sica, Faculdade de Cie ˆncias e Tecnologia, Universidade de Coimbra, P-3004-516, Coimbra, Portugal Correspondence e-mail: jap@pollux.fis.uc.pt Received 12 June 2008; accepted 26 June 2008 Key indicators: single-crystal X-ray study; T = 293 K; mean (C–C) = 0.003 A ˚ ; R factor = 0.043; wR factor = 0.117; data-to-parameter ratio = 21.3. The title steroid, C 23 H 35 ClO 4 , is a pregnane derivative prepared by ring opening of the corresponding 5,6-epoxy steroid with BiCl 3 . There are two symmetry-independent molecules in the asymmetric unit that show no significant differences concerning bond lengths and angles. The confor- mation of the six-membered rings in both molecules is close to a chair form, while the five-membered ring adopts an envelope conformation. All rings in both molecules are trans-fused. The molecules are held together by an extensive O—HO hydrogen-bonding network. Related literature For related literature, see: Pinto et al. (2007a,b,c); Spickett et al. (2000); Mori et al. (1996), Iwashima et al. (2001), Dorta et al. (2004); Nittala et al. (1981); Cremer & Pople (1975). Experimental Crystal data C 23 H 35 ClO 4 M r = 410.96 Monoclinic, P2 1 a = 7.6862 (6) A ˚ b = 27.484 (2) A ˚ c = 11.1863 (9) A ˚  = 110.094 (2)  V = 2219.2 (3) A ˚ 3 Z =4 Mo K radiation  = 0.20 mm 1 T = 293 (2) K 0.29  0.24  0.23 mm Data collection Bruker APEX CCD area-detector diffractometer Absorption correction: multi-scan (SADABS; Sheldrick, 2000) T min = 0.895, T max = 0.956 55742 measured reflections 10978 independent reflections 7889 reflections with I >2(I) R int = 0.032 Refinement R[F 2 >2(F 2 )] = 0.042 wR(F 2 ) = 0.117 S = 1.00 10978 reflections 515 parameters 1 restraint H-atom parameters constrained Á max = 0.22 e A ˚ 3 Á min = 0.26 e A ˚ 3 Absolute structure: Flack (1983), 5188 Friedel pairs Flack parameter: 0.04 (4) Table 1 Hydrogen-bond geometry (A ˚ ,  ). D—HA D—H HA DA D—HA O5A—H5AO20A i 0.82 1.98 2.795 (2) 171 O5B—H5BO20B ii 0.82 1.98 2.783 (2) 165 Symmetry codes: (i) x  1; y; z  1; (ii) x; y; z  1. Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97. This work was supported by Fundac ¸a ˜o para a Cie ˆncia e a Tecnologia. RMAP thanks FCT for a grant (SFRH/BD/18013/ 2004). Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IM2073). References Bruker (2003). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358. Dorta, E., Dı ´az-Marrero, A. R., Cueto, M., D’Croz, L., Mate ´, J. L., San-Martı ´n, A. & Darias, J. (2004). Tetrahedron Lett. 45, 915–918. Flack, H. D. (1983). Acta Cryst. A39, 876–881. Iwashima, M., Nara, K., Nakamichi, Y. & Iguchi, K. (2001). Steroids, 66, 25–32. Mori, K., Nakayama, T. & Sakuma, M. (1996). Bioorg. Med. Chem. 4, 401–408. Nittala, S. S., Velde, V. V., Frolow, F. & Lavie, D. (1981). Phytochemistry, 20, 2547–2552. Pinto, R. M. A., Ramos Silva, M., Matos Beja, A. & Salvador, J. A. R. (2007a). Acta Cryst. E63, o2138–o2139. Pinto, R. M. A., Ramos Silva, M., Matos Beja, A., Salvador, J. A. R. & Paixa ˜ o, J. A. (2007b). Acta Cryst. E63, o3321. Pinto, R. M. A., Salvador, J. A. R. & Le Roux, C. (2007c). Tetrahedron, 63, 9221–9228. Sheldrick, G. M. (2000). SADABS. University of Go ¨ttingen, Germany. Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Spek, A. L. (2003). J. Appl. Cryst. 36, 7–13. Spickett, C. M., Jerlich, A., Panasenko, O. M., Arnhold, J., Pitt, A. R., Stelmaszynska, T. & Schaur, R. J. (2000). Acta Biochim. Pol. 47, 889–897. organic compounds o1420 Pinto et al. doi:10.1107/S1600536808019478 Acta Cryst. (2008). E64, o1420 Acta Crystallographica Section E Structure Reports Online ISSN 1600-5368