Cholestane 3/3-methoxy

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

Levisalles and co-workers have prepared A-homo-5a-cholestan-4-one by the dibromocarbene procedure starting with 3-methoxy-5a-cholest-2-ene. Wieland and Anner have converted 19-mesyloxy-A -3-keto steroids into... 

The methyl ester (100, R = CH3), derived from this A-nor acid by treatment with diazomethane, is different from the ester (102) obtained either by Favorskii rearrangement of 2a-bromo-5a-cholestan-3-one (101) or by the action of cyanogen azide on 3-methoxy-5a-cholest-2-ene (103) followed by hydrolysis on alumina. The ketene intermediate involved in photolysis of (99) is expected to be hydrated from the less hindered a-side of the molecule to give the 2j -carboxylic acid. The reactions which afford (102) would be expected to afford the 2a-epimer. These configurational assignments are confirmed by deuteriochloroform-benzene solvent shifts in the NMR spectra of esters (100) and (102). ... 

Maleic anhydride, 348 Manganese dioxide, 156, 426, 428 Mattox rearrangement, 216 2/8-Mesyloxy-3a-azido-5a-cholestane, 28 3 -Methoxy-17a-aminomethy lestra-1,3,... 

This rule was applied to the stereochemical assignment of 3-substituted 5a- and 5/J-hydroxy-cholestan-6-one oximes and the corresponding 5-methoxy derivatives290. The E configuration of the oxime group was deduced from the C-7 chemical shift by comparison with S (C-7) of the corresponding cholestan-6-one29 . 

Babcock and Fieser obtained 3P-methoxy steroids by hydrogenation of methyl 3-oxo-A-91-11 1 -cholenate (5), methyl dehydrolithocholate (6), and 5a-cholestan-3-one (7) over Adams platinum oxide in methanol in the presence of hydrobromic acid (eq. 5.31 ).98 It is noted that the P-methoxy isomers were produced from the ketones of both 5p (5 and 6) and 5a series (7). 

Reduction of 6 methoxy-3a -eych-S(ic-steroids. Reduction of 6)8-methoxy-3a,5-cydocholestane (1) with mixed hydride affords as the major product 3ot,5-cyclo-5 -cholestane (2). 

Palladium hydroxide catalyst [1,782, before Pentachlorophenol]. This hydrogenation catalyst is prepared by adding a slight excess of lithium hydroxide solution to a hot aqueous solution of palladium chloride the precipitate is washed to neutrality with hot distilled water.1 Reduction of cyclohexanones in an alcohol with prereduced palladium hydroxide as catalyst gives cyclohexyl ethers in high yield.2 Thus 5a-cholestane-3-one gives /8-methoxy-5a-cholestane in 91% yield when reduced in methanol. Hydrogenation of cyclohexanol in ethanol affords ethoxycyclohexane in 96% yield. 

Reduction of cyclohexanones in MeOH or EtOH with prereduced palladium hydroxide as catalyst affords cyclohexyl ethers. For example, 5a-cholestane-3-one gives /3-methoxy-5a-cholestane undergoes reduction in 91 % yield in methanol. Hydrogenation of cyclohexanones in ethanol leads to ethoxycyclohexanes ... 

Cholest-4-ene and -5-ene add methanol photochemically to give 5-methoxy-5a-and -5)3-cholestanes, the latter predominating. Propan-2-ol affords only the 5/S-isopropoxy-derivative, along with the 5a- and 5)3-ols as major products. 

Conflicting reports relating to the products obtained from the Tiffeneau-Demjanov ring-expansion of 5a-cholestan-3-one have appeared. G.Lc. analysis has failed to reveal the presence of the A-homo-3-ketone, although it has been detected by o.r.d. and c.d. measurements. The pure A-homo-4-ketone has now been obtained via solvolysis of the dibromocarbene adduct (309) of 3-methoxy-cholest-2-ene to afford the unsaturated halogenoketone (310) which was then reduced to the 4-one. In a similar manner, 3-acetoxycholest-3-ene afforded the isomeric unsaturated halogenoketone (311) which on reduction produced A-homo-5a-cholestan-3-one. 

Several routes applicable to the large scale conversion of testosterone into 4,5a-dihydrotestosterone have been investigated. The method of choice appears to be via catalytic reduction of a 17-acyloxy-3,3-ethylenedioxyandrost-5-ene. Platinum-catalysed hydrogenation of 19-acetoxy, hydroxy-, or methoxy-cholestan-3-ones affords higher proportions of 3a-alcohols than does the 19-unsubstituted steroid. Tritiation of 17)S-hydroxyandrosta-l,4-dien-3-one affords testosterone having a tritium ratio of 1 3.4 (a P) at C-1 and 1 1.4 at C-2 implying that reduction must proceed, in part, by 1,4-addition. ... 

In Eisessig unter Zusatz starker Sauren konnen die Alkohole als Ester anfallen. In me-thanolischer Salzsaure werden Ather gebildet4. 3-Oxo-choIestan wird in Metha-nol/Bromwasserstoffsaure in guter Ausbeute zum3ft-Methoxy-t holestan (70% d.Th.) hydriert5, wahrend in Eisessig/Salzsaure 3[Pg.90]

Photolysis of 3/3-acetoxy-5-methoxy-5a-cholestan-6-one in MeOH gave a high yield of methyl 3/3-acetoxy-5-methoxy-5,6-seco-5or-cholestan-6-oate whereas in benzene the corresponding carboxylic acid was obtained. The studies on the photochemistry of 4-methoxycholest-4-en-3-one have been extended to include the compounds (225). The oxetanones (226) andoxetanols (227) were generally formed except in the case where R = H, = Ph, when the corresponding oxetanone (226) was not formed. 3-Methoxycholest-2-en-4-one... 

Anodic decarboxylation of the glycidates (415) derived from 5a-cholestan-3-one gave 3-acetal-5a-cholest-2-ene (416) and a 3-acetyl-3-methoxy-derivative (417). "... 

The effect of 3a- and 3/5-hydroxy-, 3a- and 3j8-acetoxy-, 3-ethylene ketal and 3a-methoxy-derivatives of cholest-5-ene on the addition of the Simmons-Smith reagent has been investigated. The addition of the reagent occurred only with epi-cholesterol (312) to give mainly 3a-hydroxy-5,6a-cyclopropano-5a-cholestane (313) (see Chapter 1, refs. 153—155). 

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