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Query: UMLS:C0338671 (Steroids)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A variety of delta5-steroids were converted into alpha, beta-unsaturated 7-ketones using a modification of the already known method of t-butyl hydroperoxide in the presence of copper iodide in acetonitrile. The same alteration was applied to another oxidative procedure, which had never been used before on steroidal substrates. The same oxidative agent was used in the presence of copper iodide, and tetra-n-butylammonium bromide was used as a phase-transfer catalyst in a two-phase system of water/methylene chloride. It was found that the allylic oxidation proceeded more efficiently when t-butyl hydroperoxide was added to the reaction mixture in portions. The initial addition of the total amount of oxidant or its dropwise addition afforded low yields. This observation contributes to the investigation of the reaction mechanism, and high-yield conversions of steroidal 5,6-enes into the corresponding conjugated 7-ones in short reaction times are reported.
Steroids 2003 May
PMID:Optimization of the allylic oxidation in the synthesis of 7-keto-delta5-steroidal substrates. 1279 91

Allylation of an 11-oxo-steroid, the protected adrenosterone, was studied to examine more closely the steric hindrance of such a ketosteroid. While the beta face exhibits, as well known, a strong steric hindrance, the alpha side appears to be only relatively hindered. A high diastereoselectivity was observed in the addition of crotyl magnesium bromide.
Steroids 2004 Jan
PMID:Are the 11-oxo-steroids really so hindered towards organometallic compounds? 1471 73

The previously reported analog of pregnenolone having a 3,4-dihydro-2H-pyran attached via a Cz.sbnd;C bond to the C-20 position (1), stereoselectively reacts with m-chloroperoxybenzoic acid in methanol at -5 degrees C. Acid-catalyzed hydrolysis of the isolated intermediates gives good yields of mostly a new 27-norcholesterol analog: (20R,23R)-3,20,23,26-tetrahydroxy-27-norcholest-5-en-22-one-3-acetate (2a, and a smaller amount of its 23S enantiomer 2b). Three different conditions of epoxidation and methanolysis followed by acid-catalyzed hydrolysis typically produce approximately 2:1 ratios of the 23R:23S diastereoisomers with a C-23 hydroxy group at the new asymmetric center. Bromine also reacts stereoselectively with (20R)-3,20-dihydroxy-(3',4'-dihydro-2'H-pyranyl)-5-pregnene (4) giving mostly (20R,23R)-23-bromo-3,20,26-trihydroxy-27-norcholest-5-en-22-one (7a). Thus both major steroidal products 2a and 7a have the same C-23R configuration. Assignment of molecular structures and the absolute configurations to 1 and 2a were based on elemental analysis, mass spectra, nuclear magnetic resonance, FTIR infrared spectroscopic analysis and X-ray crystallography. Mechanisms are discussed for stereochemical selectivity during epoxidation and bromination of the 3,4-dihydro-2H-pyranyl ring in 1 and 4.
Steroids 2004 Jan
PMID:Stereoselective reactions of (20R)-3,20-dihydroxy-(3',4'-dihydro-2'H-pyranyl)-5-pregnene derivatives form 27-nor-3,20,23,26-tetrahydroxy-cholesten-22-ones and related bromo ketones. 1471 75

3alpha,17beta-Dihydroxy-3beta-methyl-5alpha-androstan-6-one (1) and 3beta,17beta-dihydroxy-3alpha-methyl-5alpha-androstan-6-one (13) were prepared by the reaction of methylmagnesium bromide with the 3-ketosteroids. Structures and configurations in position 3 were determined by NMR spectra. Substitution in the position 6 influences the ratio of the products.
Steroids 2004 Sep
PMID:Synthesis of 3-methyl-3-hydroxy-6-oxo-androstane derivatives. 1546 4

The stereochemistry of the addition of methylmagnesium bromide to a steroidal 4,5-epoxy-3-ketone has been shown to be determined by the stereochemistry of the epoxide. The epoxidation to the corresponding 3-alkyl-3-hydroxy-4-enes by per-acid was determined by the stereochemistry of the allylic alcohol.
Steroids 2005 Feb
PMID:The stereochemistry of the Grignard reaction of steroidal 4,5-epoxy-3-ketones. 1563 62

Four 5,6-unsaturated steroids--3beta-chlorocholest-5-ene (1a), cholesterol (1b) and its acetate (1c) and benzoate (1d)-were subjected to constant current electrolysis (50 mA, 2 F mol(-1)) in an electrolytic cell divided by a ceramic membrane, using a platinum foil as the anode and a graphite stick as the cathode. When electrolysis was carried out in a solution of tetraethylammonium bromide in aprotic solvents (dichloromethane, acetonitrile or acetic anhydride), the addition of electrochemically-generated elemental bromine onto the double bond of the cholesterol derivatives gave their corresponding 5alpha,6beta-dibromosteroids--3beta-chloro-5alpha,6beta-dibromocholestane (2a), 5alpha,6beta-dibromocholestan-3beta-ol (2b), 5alpha,6beta-dibromocholestan-3beta-yl acetate (2c) and 5alpha,6beta-dibromocholestan-3beta-yl benzoate (2d)--as the sole products, and in good yields (58-91%). However, the electrolysis of steroids 1a-c in a solution of tetraethylammonium bromide with methanol as the solvent proceeded to give, in addition to dibromides 2a-c, the corresponding diastereomeric pairs of 5-bromo-6-methoxysteroids: 5alpha-bromo-3beta-chloro-6beta-methoxycholestane (3a) and 5beta-bromo-3beta-chloro-6alpha-methoxycholestane (4a), 5alpha-bromo-6beta-methoxycholestan-3beta-ol (3b) and 5beta-bromo-6alpha-methoxycholestan-3beta-ol (4b) and 5alpha-bromo-6beta-methoxycholestan-3beta-yl acetate (3c) and 5alpha-bromo-6beta-methoxycholestan-3beta-yl acetate (4c). The benzoate 1d was not soluble enough in methanol, even with heating. The products were characterized by physical and spectral data (IR, 1H NMR and 13C NMR). Single crystal X-ray structure determinations of compounds 2a and 3a are also reported.
Steroids 2005 Dec 01
PMID:Electrochemical bromination of cholest-5-enes. 1603 78

5alpha-Androst-1-ene-3,17-dione (5) as a prodrug of 1-testosterone (4) was prepared in four steps from 17beta-Acetoxy-5alpha-androstan-3-one (stanolone acetate) (1) in high yield. Thus, stanolone acetate (1) was brominated in the presence of hydrogen chloride in acetic acid to give 17beta-acetoxy-2-bromo-5alpha-androstan-3-one (2), which underwent dehydrobromination using lithium carbonate as base with lithium bromide as an additive to give 17beta-acetoxy-5alpha-androst-1-en-3-one (3) in almost quantitative yield with 97% of purity. Compound (3) was hydrolyzed with sodium hydroxide to give 17beta-hydroxy-5alpha-androst-1-en-3-one (4,1-testosterone), which was oxidized with chromium trioxide to afford 5alpha-androst-1-ene-3,17-dione (5). The overall yield of 5 was 78.2% with purity of 99%. In this method, the formation of 4-ene was diminished when 1-ene was introduced, and its mechanism was also discussed.
Steroids 2006 Dec
PMID:An efficient synthesis of 5alpha-androst-1-ene-3,17-dione. 1712 59

This study aimed at the synthesis of novel structurally promising steroidal heterocycles and to elucidate the potential role of these compounds as antibacterial agents. Epi-androsterone 1 reacted with CS2 and sodium hydride in dimethylsulfoxide to yield alpha-oxoketene dithiodisodium salt 2. The non-isolable salt 2 reacted with acetyl chloride, benzoyl chloride, phenacyl bromide and iodomethane to afford the corresponding alpha-oxodithioacetal derivatives 4a,b, 6 and 7, respectively. Interaction of 2 with the alkyl halide reagents 8a-d yielded the corresponding thiophene derivatives 10a-d. Alpha-oxoketene dithioacetal 7 reacted with urea and thiourea to furnish the pyrimidinoandrostane derivatives 12a,b. Compound 7 also reacted with ortho-phenylene diamine and ortho-aminophenol 13a,b to produce the dinucleophilic adducts 15a,b. The in vitro antibacterial evaluation of some newly prepared compounds showed that all compounds have high significant antibacterial activity against the used strains of gram positive and gram negative bacteria.
Steroids 2007 May
PMID:Synthesis of novel steroidal heterocyclic derivatives as antibacterial agents. 1738 37

An efficient method to prepare 5, 9-cyclo-1, 11-oxido-pregn-16-ene-3, 20-dione in one pot was reported. Treatment of 9-bromide-11-hydroxypregna-1, 4, 16-trien-3, 20-dione with Raney Ni in absolute ethanol afforded 5, 9-cyclo-1, 11-oxido-pregn-16-ene-3, 20-dione by two annulation reactions in reasonable yield. The absolute configuration was also confirmed by X-ray crystal analysis.
Steroids 2009 Feb
PMID:An efficient one-pot synthesis of 5, 9-cyclo-1, 11-oxido-pregn-16-ene-3, 20-dione from 9-bromide-11-hydroxypregna-1, 4, 16-trien-3, 20-dione by two annulation reactions. 1904 60

Novel delta-alkenyl phenylhydrazones were synthesized in both the estrone and the 13alpha-estrone series. Electrophile-induced cyclizations of alkenyl phenylhydrazones with phenylselenyl bromide furnished cyclic iminium salts, via attack of the imino nitrogen atom on the intermediate seleniranium ion. Hydride reduction of the iminium salts led to novel aminophenyl-substituted aza-D-homoestrones. The structures of the new products were determined by NMR (one- and two-dimensional) and MALDI-MS techniques, with C(70) fullerenes as matrix in the latter case.
Steroids
PMID:Electrophile-induced generation of cyclic azomethine imines from steroidal delta-alkenyl hydrazones. 1917 Nov 61


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