Molecular Rearrangements in the Sterols. I. The Action of Anhydrous Potassium Acetate on Cholesteryl p-Toluenesulfonate in Acetic Anhydride Solution

Wallis, Everett S.; Fernholz, E.; Gephart, F. T.

doi:10.1021/ja01280a034

Cited by 51 publications

(11 citation statements)

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“…Cholesteryl p-toluenesulfonate, was produced by tosylation of cholesterol, as described by Wallis, 1937 and recrystallized from acetone. S---O 1 1.415 (3) C20--C21 S----O2…”

Section: Methodsmentioning

confidence: 99%

Redetermination of Cholesteryl p-Toluenesulfonate at 150K

Cox¹,

Buchanan²,

Wardell³

1996

Acta Crystallogr C

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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...

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“…Cholesteryl p-toluenesulfonate, was produced by tosylation of cholesterol, as described by Wallis, 1937 and recrystallized from acetone. S---O 1 1.415 (3) C20--C21 S----O2…”

Section: Methodsmentioning

confidence: 99%

Redetermination of Cholesteryl p-Toluenesulfonate at 150K

Cox¹,

Buchanan²,

Wardell³

1996

Acta Crystallogr C

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“…The remaining homoallylic alcohol was then masked as an i -steroid [ 29 – 30 ] ( para -toluenesulfonyl chloride, cat. 4-dimethylaminopyridine, pyridine, 25 °C; then KOAc, MeOH, 64 °C, 85% yield for the two steps) to give 8 .…”

Section: Resultsmentioning

confidence: 99%

C–H-Functionalization logic guides the synthesis of a carbacyclopamine analog

Rabe¹,

Moschner²,

Bantzi³

et al. 2014

Beilstein J. Org. Chem.

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“…Syntheses of glycosylation acceptors 9 , 13 and 17 are described in Scheme . Compound 9 was obtained in three steps from cholesterol tosylate 6 . Compound 6 was reacted with diethylene glycol in refluxing dioxane, affording product 7 in 81% yield.…”

Section: Resultsmentioning

confidence: 99%