Redetermination of Cholesteryl p-Toluenesulfonate at 150K

Abstract

Compared to a previous room-temperature study, the apparent shortening of the bond lengths in the C17 side chain of cholesteryl p-toluenesulfonate, C34H5203S, is much less pronounced at 150 K, and the uncertainties associated with the molecular geometry are much improved. CommentRoom-temperature X-ray studies of cholesteryl derivatives may show bond-length anomalies or disorder in the C17 side chain (E1-Shora, Palmer, Singh, Bhardwaj & Paul, 1984;Buchanan, Cox & Wardell, 1996a). We have recently used cholesteryl p-toluenesulfonate in the synthesis of metallated steroids (Buchanan, Cox & Wardell, 1996b) and have observed unusual geometries in this chain. The previously determined roomtemperature crystal structure of the title compound (I) (Chandross & Bordner, 1977) exhibits such features but geometrical uncertainties are high. The current lowtemperature study was performed to obtain a better molecular geometry of the steroid. The R value has improved from 0.092 to 0.049, the bond length uncertainties have decreased by a factor of about three and the apparent shortening of C---C bonds in the C 17 side chain is less obvious at 150 K. For example, C24--C25 is 1.405 (26) ,~, at room temperature and 1.496 (7) ,~, at 150 K; the corresponding values for C25--C26 are 1.479 (32) and 1.505 (7)A, respectively. It is probable that high anisotropic displacement parameters caused librational shortening of the C--C bond lengths in the room-temperature study. The tosylate group is fl to the cholesteryl moiety with H3a and ring conformations are A chair, B half-chair (the best plane is through C10, C5, C6 and C7 with C8fl and C9a), C chair, and D half-chair with C13fl and C14a. The S atom is in a distorted tetradehral environment with bond lengths and valence angles as given in Table 2. The cell volume at 150 K is 4.1% smaller than that at room temperature. ExperimentalCholesteryl p-toluenesulfonate, was produced by tosylation of cholesterol, as described by Wallis, 1937 and recrystallized from acetone. Crystal data1.312 (6) C25--C27 C 17----C201.518 (7) C25---C26112.2 (4)C31--S---O1---C3 68.6 (4)1.519 (6) 1.519 (6) 1.504 (7) 1.504 (6) 1.496 (7) 1.494 (6) 1.505 (7) The unit-cell and intensity data were collected on a Delft Instruments FAST diffractometer using the routines ENDEX, REFINE and MADONL in the MADNES software (Pflugrath & Messerschmidt, 1989) and processed using ABSMAD (Karaulov, 1992); detailed procedures are described by Darr, Drake, Hursthouse & Malik (1993). The non-H atoms were refined with anisotropic displacement parameters and H atoms were allowed to ride on their attached C atoms with a common isotropic displacement parameter. Data collection: MADNES (Pflugrath & Messerschmidt, 1989). Cell refinement: ABSMAD (Karaulov, 1992). Program(s) used to solve structure: SHELXS86 (Sheldrick, 1990). Program(s) used to refine structure: SHELXL93 (Sheldrick, 1993). Molecular graphics: ZORTEP (Zsolnai, 1995).The use of the EPSRC X-ray Crystallographic Service at The University of Wales, Cardiff, is gratefully ac...

(25R)-6α-Hydroxy-5α-spirostan-3β-yl tosylate

“…4.4 Å. On the other hand, the tosylate orientation in the title compound is similar to that observed in cholesteryl tosylate (Cox et al, 1996), which has C-6 engaged in a double bond. This suggests that the tosylate orientation results from packing restraints or intermolecular interactions rather than intramolecular contacts.…”

“…For the hydroboration-oxidation synthetic step used for the preparation of the title compound, see: Smith & Pelter (1991); Brown (1962). For the structure of another steroid functionalized at C-3 with a tosylate group, see: Cox et al (1996).…”

Steroids: reactions and partial synthesis

“…Another interesting structure that has been reported 22 is that of the lactone, ecdysantherin 9, which was obtained from Ecdysanthera rosea, a Vietnamese plant used as an antiinflammatory drug. X-Ray crystal structures have been reported for a 17 -estradiol 3-benzoate, 23 a fluorinated D-homoestrone 10, 24 17 -benzyl-17 -hydroxy-16-hydroxyimino-3-methoxyestra-1,3,5(10)triene, 25 derivatives, [27][28][29] cholesteryl 3 -toluene-p-sulfonate, 30 a fungal ergostane 12, 31 and some cholestane derivatives [32][33][34] including a 3-stannylcholest-5-ene. 35 An investigation of the gas phase photoelectron spectrum of dehydroepiandrosterone has shown 36 that the lowest energy ionization event corresponds to the -ionization energy closely followed by the carbonyl lone pair ionization.…”