Cholestanol methyl ether

The relative reactivity of primary and secondary positions adjacent to oxygen can be strongly dependent on the nature of the oxidant. For example, treatment of the methyl ethers (8) and (10) with chromium trioxide in acetic acid leads to the formation of the formates (9) and (11), respectively (equations 13 and 14). In direct contrast, n-decyl methyl ether is oxidized exclusively to methyl n-decanoate (83% yield) by ruthenium tetroxide (equation 11). Under similar reaction conations, 3 -cholestanol methyl ether gives cholestan-3-one as the mqjor product, togedier with traces of the corresponding formate. Therefore, at least in the case of ruthenium tetroxide, primary positions appear to be more reactive than tertiary. 

A detailed procedure for the preparation of cholestanyl methyl ether from cholestanol has been published 11) and a survey of the usefulness of the reagent has also appeared 12). There appears to be no particular advantage to this procedure over the more convenient alternatives given above. 

ChOLESTANE, 30-METHOXY-, 41, 9 Cholestanol, etherification of, 41, 9 Cholestanyl methyl ether, 41, 9 Cinnamaldehyde, reaction with Wittig reagent, 40,86... 

Catalyst for methylatUm with diazomethane. Saturated alcohols do not react with diazomethane alone but afford methyl ethers under catalysis by fluoroboric acid or boron trifluoride. Neeman and Johnson give a detailed procedure for the conversion of cholestanol into the methyl ether in 95% yield by reaction in ether-methylene chloride in the presence of fluoroboric acid. 

Ethers, Esters, and Related Derivatives of Alcohols.—5a-Cholestanyl methyl ether has been cleaved inter alia) and converted into 5a-cholestanol by successive treatment with trimethylsilyl iodide and water.Pyridinium toluene-p-sulphonate has been reported as an efficient and mild catalyst for the conversion of alcohols into their tetrahydropyranyl ethers.Bile acids were efficiently performylated by treatment with 90% HCO2H-HCIO4. Selective base-catalysed... 

Internal Standard Solution Transfer about 1 g of (3-cholestanol (5a-cholestan-3(3-ol), accurately weighed, into a 10-mL volumetric flask, dissolve in and dilute to volume with methyl-tertiary butyl ether to a final concentration of 100 mg/mL. 

After concentration under nitrogen at 37°C, sterols were derivatized to sllyl ethers with BSTFA (Pierce Chemical Co.). The derivatized sterols were then diluted to a known volume In chloroform containing 100 plcomoles of hexadecane, cholestane, cholestanol, cholesterol, stlgmasterol and sitosterol as Internal standards. The mixture was then analyzed with a Hewlett-Packard 5880A GC equipped with a flame Ionization detector. Separations were achieved with a Hewlett-Packard 50m x. 322 mm ID crosslinked methyl silicone fused silica capillary column. The column temperature was held Initially at 50 °C for 1 min, programmed at 10 °C/min to 160°C, then 4 °C/min to a final temperature of 300°C. Samples were Injected via the splltless method (23) with the Injector at 375°C. The splitter was turned on at 30 sec. The FID was held at 350°C. 

---