Cholestenones

The reaction is illustrated by the preparation of cholestenone from cholesterol the double bond migrates from the Py to the ap position during the oxidation ... 

Cholestenone. Place a mixture of 1 0 g. of purified cholesterol and 0-2 g. of cupric oxide in a test-tube clamped securely at the top, add a fragment of Dry Ice in order to displace the air by carbon dioxide, and insert a plug of cotton wool in the mouth of the tube. Heat in a metal bath at 300-315° for 15 minutes and allow to cool rotate the test-tube occasionally in order to spread the melt on the sides. Warm with a few ml. of benzene and pour the black suspension directly into the top of a previously prepared chromatographic column (1) rinse the test-tube with a little more benzene and pour the rinsings into the column. With the aid of shght suction (> 3-4 cm. of mercury), draw the solution into the alumina column stir the top 0 -5 cm. or so with a stout copper wire to... 

Dihydrocholesterol has been prepared by the reduction of cholestenone with sodium and amyl alcohoP and by the hydrogenation of cholesterol. In the presence of platinum black or platinum oxide, yields varying from 6.5 per cent to 40 per cent have been obtained in ether, acetone, ethyl acetate, and acetic acid. ... 

Table 3-1 illustrates the influence of solvent polarity on the amount of 6W-product e.g. 10) formed from hydrogenation of octalone (9), testo-sterone and cholestenone. The product composition is determined by the amount of 1,2 and 1,4 adsorption of the substrate. 

A solution of 0.2 g of cholestenone and 0.47 g of (< 3P)3RhCl in 150 ml of acetone is stirred under a hydrogen atmosphere for 3 days. The solvent is evaporated and the residue separated by thin layer chromatography to afford 5a-cholestan-3-one in 25-35% yield. ... 

The double bond of a, -unsaturated ketones reacts with nitrosyl fluoride but only at room temperature and in small yield. Cholestenone produces a 4.2% yield of a 4< -fluoro-5( -nitro-3-ketone (46) after alumina chromatography. Similarly, the A -20-ketone grouping in 3j5-acetoxypregna-5,16-dien-20-one (47) reacts to form after chromatography a 14% yield of the... 

A-Homo-cholest-4a-en-3-one (16a) A total of 200 ml of a cold 0.232 M solution of diazomethane in methylene dichloride is added dropwise to a stirred solution of cholestenone (15a 5.6 g) in anhydrous methylene dichloride (25 ml) containing freshly prepared fiuoroboric acid catalyst. Nitrogen evolution begins immediately, and after 5 min the colorless solution turns cloudy due to precipitated polymethylene. After the addition is complete, the mixture is stirred for 1 hr and filtered. The filtrate is diluted with ether, washed with saturated sodium bicarbonate solution followed by... 

Peroxytnfluoroacetic acid in the presence of sulfuric acid can be employed for the selective one-step oxidation of the saturated side chain of cholestenone [if] (equation 17)... 

A 250-mI round-bottom flask fitted with a condenser (drying tube) is charged with a mixture of 2-bromocholestanone (4.7 g, 0.01 mole), lithium carbonate (7.4 g, 0.10 mole), and 100 ml of dimethylformamide. The system is flushed with nitrogen and then refluxed (mantle) for 18-24 hours. After the reflux period, the solution is cooled and poured into 500 ml of water. The aqueous mixture is extracted with 50 ml of ether, the ether extract is dried (sodium sulfate), and the ether is removed (rotary evaporator). The residue may be recrystallized from ethanol or methanol. J -Cholestenone is a white solid, mp 98-100°. 

EC1 Oxidoreductases dehydrogenase, acceptor ECU Acting on the CH-CH (cholestenone 5a- Choline oxidase choline H202 Luminol 17... 

Chloropentammine Ir (HI) complex, incomplete Ir (III) autoreduction, 39 151-152 Chloroplasts, quantum conversion in, 14 1 1 -Chloroprop-2-ene thermal decomposition, 41 80 Chlorpromazine, reactivity with EDA complexes, 20 333, 336 CH O, 32 374-375 CH3OH, oxidation, 38 21-23 Cholestenone, hydrogenation, 25 57, 58 Cholesterol, biosynthesis of, 25 382 Cholinesterases, stracture of active surface, 10 130... 

Reduction of steroid enones like cholestenone 26, with a rigid ring conformation, leads to head-to-head pinacol dimers because of steric hindrance at the alternative dimerization site, and reaction occurs tlnough the a-face of the radical intermediate [101, 102]. The a-face is opposite to the angular methyl substituent... 

Fig. 4. Oraph Olustfuting Uie dependence of capacity ratios on the composition of eluents containing n-heptane and dichloromethane. The stationary phase is LiChrosorb SI 100 silica gel. Sample A, ethyl benzene B. anthracene C, m-terphenyl D, nitrobenzene F. benzonitrile F, benzophenone O, acetophenone H, l,4..Vxylenol I, r>-nitroaniline J, m nitioaniline K, A -cholestenone L, p-nitroaniline.

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