Cholesteryl acetate

Chloro-a,/3-unsaturated aldehydes condense with ammonium thiocyanate to give isothiazoles (76EGP122249). 2,3-Diphenylcyclopropenone reacts with iV-sulfinyl-cyclohexylamine in the presence of nickel tetracarbonyl to give the isothiazolin-3-one 1-oxide (197) (79SST(5)345). Cholesteryl acetate reacts with trithiazyl trichloride in pyridine to give the isothiazolo steroid (198) (77JCS(P1)916). 

A) From Cholesieryl Acetate (Note 6).-—Five grams of cholesteryl acetate (Note 7) and o.r g. of platinum oxide are... 

A solution of 10 g (0.023 mole) of cholesteryl acetate (mp 112-114°) in ether (50 ml) is mixed with a solution containing 8.4 g (0.046 mole) of monoperphthalic acid (Chapter 17, Section II) in 250 ml of ether. The solution is maintained at reflux for 6 hours, following which the solvent is removed by distillation (steam bath). The residue is dried under vacuum and digested with 250 ml of dry chloroform. Filtration of the mixture gives 6.7 g of phthalic acid (87% recovery). The solvent is evaporated from the filtrate under reduced pressure and the residue is crystallized from 30 ml of methanol, giving 6.0 g (58% yield) of -cholesteryl oxide acetate. Recrystallization affords the pure product, mp 111-112°. Concentration of the filtrate yields 1.55 g (15% yield) of a-cholesteryl oxide acetate which has a mp of 101-103° after crystallization from ethanol. 

The sample LCs used in their experiments were cholesteryl esters with low molecular weight cholesteryl acetate... 

Figure 34 Excerpts of two-dimensional HMBC spectra of cholesteryl acetate recorded on a Bruker Avancell 400 MHz spectrometer (A) with the standard HMBC pulse sequence (Figure 1), and (B) with the IMPACT-HMBC experiment depicted in Figure 30. The same contour levels are used for all spectra. In (A), F, ridges are still visible (indicated by a vertical arrow), while they are very efficiently suppressed in (B). The proposed sequence results in signals with no coupling structure, as a result of the incorporation of a constant-time period. The improved peak dispersion is shown for the correlation between C-3 and H-2 (expanded in the small boxes). Asterix and the dashed box indicate residual Vch signals. The measurement duration was 22 min for both experiments.

An asymmetric C-H insertion using a chiral 3,3, 5,5 -tetrabromosubstituted (salen)manganese(m) complex 107 with TsN=IPh afforded insertion products with ee up to 89%.258 Che reported the first amidation of steroids such as cholesteryl acetate with (salen)ruthenium(n) complexes 108.259... 

Sjostrom, B. and Bergenstahl, B., Preparation of snbmicron drng partides in lecithin-stabilized o/w emnlsions. I. Model stndies of the precipitation of cholesteryl acetate. Int. J. Pharm., 88, 53-62, 1992. 

The unusual system franx-RulOl lTMPl/N OllO atm)/fluorobenzene epoxidised linear alkenes, cholesteryl acetate and the ferf-butyldimethylsilyl ether of citronellol [592] cholest-5-ene-3-one was oxidised to the 6a and 6p alcohols and the enedione by franx-RulOl lTMPl/OXCgH (Table 3.2) [593]. With ter-penes the 6,7-double bonds were selectively epoxidised by fran -Ru(0)2(TMP)/... 

Ru(0)(0jR)2 (R=7,8-didehydrocholesteryl acetate and cholesteryl acetate). These esters were isolated from RuO (as RuO /aq. Na(I04)/acetone) and R, and were shown by H and NMR and mass spectrometry to be Rn(VI) diesters similar to those obtained from the alkenes R with OsO. Their isolation, despite the absence of X-ray structural studies, suggests that such diesters could be involved in reactions of RuO, as indeed they are in the corresponding reactions with OsO. In each case a pair of isomeric diesters was formed (Fig. 1.31) [323, 346]. 

The hydroperoxides obtained on thermal oxidation of cholesteryl acetate (191e) can be selectively separated by SPE and elution with a polar solvent. After reduction to the corresponding alcohols by NaBH4 and further derivatization to the trimethylsilyl ether, the products can be subjected to GLC with ion-trap MS detection. It can be thus demonstrated with the aid of standards that under the oxidation conditions (160 °C for 90 min) only the 7-position is attacked, leading to the la- and 7/3-hydroperoxy derivatives, while the plausible 4-position remains unscathed . Treatment of erythrocite ghosts with t-BuOOH causes a manyfold content increase of 5-hydroxyeicosatetraenoic acid (5-HETE), 5-hydroperoxyeicosatetraenoic acid (5-HPETE) and 5-oxoeicosatetraenoic acid (5-oxo-ETE) residues of phospholipids. These acids can be separated by HPLC, identified and quantitized by tandem MS . ... 

SCHEME 11. Ozonolysis of cholesteryl acetate in alcohol solution and subsequent derivatization... 

Lithium aluminum hydride, cholesteryl acetate ozonolysis, 696... 

Fig. 2.45. Signal intensities of CH. CH2 and CH3 groups as functions of the polarization transfer angle 0y. The proton-decoupled signals of C-9 (CH), C-l (CH2) and C-18 (CH3) in cholesteryl acetate (100 mg/mL in deuteriochloroform) are observed at 100.6 MHz [56],...

Solv. Ref. C- Cholesteryl acetate Dioxane/CHCl3 [65 a] Cholesteryl methyl ether Dioxane/CHCl3 [65 a] 7-Dehydro- cholesteryl acetate Dioxane/CHCl3 [65 a] Ergostcrol Dioxane/CHCl3 [65 a] Lanosterol CDC13 [587] Dihydro- lanosterol CDC13 [587]... 

Price, F. P. and Wendorff, J. H. Transitions in mesophase forming systems. II. Transformation kinetics and properties of cholesteryl acetate. J. Phys. Chem. 75, 2849 (1971)... 

If the acetic acid is not removed some cholesteryl acetate may be formed during the evaporation. 

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