5α-Cholestane

5α-Cholestane is a sterol that has been found in dust samples from urban and rural paved and agricultural and public unpaved roads. It has been used as an internal standard for the quantification of phytosterols by HPLC-MS/MS and fecal sterols by GC-FID and GC-MS.

WHITE CRYSTALLINE POWDER

5α-Cholestane was used as standard in cholesterol analysis by GC and HPLC.

α-Cholestane is the trans-decalin homolog of Coprostane.

ChEBI: The 5alpha-stereoisomer of cholestane.

5α-Cholestane is a sterol produced endogenously from cholesterol and has been isolated from human feces. It is derived from cholesterol by the action of intestinal microorganisms. Derivatives of 5α-cholestane in plants are called Brassinosteroids that selectively activate the PPI3K/Akt pathway.

In a reaction flask equipped with a stirrer, thermometer, ventilating duct, and reflux condenser (with calcium chloride drying tube), add 250 mL of anhydrous ether, cool to -10 to -15C, and slowly pass the hydrogen chloride into the body for about 45 min. and then add cholesterol ketone at -15C

(2) 10 g (0.0216 mol). The reaction mixture was then cooled to -20C and 12.3 g (0.19 mol) of active zinc (1) was added in 2 to 3 minn. The temperature was slowly increased to -5C and the reaction was stirred at -5 to 0C for 2 h. The reaction was then cooled to -15C and the reaction was slowly poured into 130 g of crushed ice with thorough stirring. The organic layer was separated and the aqueous layer was extracted with ether. The ether solutions were combined, washed with saturated sodium chloride and dried over anhydrous sodium sulfate. The ether was evaporated to give a colorless liquid, which solidified on cooling. The solid was dissolved in 30-40mL of hexane, passed over a silica gel column and eluted with hexane. Hexane was evaporated under reduced pressure to give 8 to 8.2 g of cholestane

(1) in 82% to 84% yield. Recrystallized with ethanol-ether, obtained flaky crystals 7.3-7.5g, mp 78-79C. Note: Activated zinc can be prepared as follows: 16g of zinc powder which passes through 300 mesh sieve is soaked in 100mL of 2% hydrochloric acid for about 4min until the surface of the zinc powder is shiny. Pour off the dilute hydrochloric acid and wash with distilled water 4 times. Filtered, washed with sufficient water, and then washed with ethanol, acetone and ether sequentially. And then dried in vacuum at 85 ~ 90 to obtain 13 ~ 14 g of active zinc, immediately used in the reaction.

Crystallise 5-cholestane from Et2O/EtOH or EtOAc. [Ruzicka et al. Helv Chim Acta 16 327 1933, Beilstein 5 III 1132, 5 IV 1227.]

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