- Oxidations with potassium permanganate - Metal sulphates and nitrates. β-selective epoxidation of Δ5-unsaturated steroids
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The β-epoxidation of 3β-acetoxy-Δ5-unsaturated steroids has been achieved with numerous potassium permanganate-metal sulphates and nitrates with a high degree of stereoselectivity. 5β,6β-Epoxides are formed in a one step reaction in good yields and using very low cost reagents. The best results were achieved with KMnO4/Fe2(SO4)3.nH2O.
- Salvador,Sa E Melo,Campos Neves
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- A Convenient Synthesis of 5,6β-Epoxides of Some Cholesteryl Esters and Δ5-Ketosteroid Derivatives by Catalytic β-Stereoselective Epoxidation
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The epoxidation of a series of cholesteryl esters by air in the presence of a catalytic amount of a ruthenium tetramesitylporphyrin complex is described.The preparative procedure, which requires only 4 to 5 mol percent of the catalyst, leads to high conve
- Marchon, Jean-Claude,Ramasseul, Rene
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- Highly stereoselective epoxidation with H2O2 catalyzed by electron-rich aminopyridine manganese catalysts
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Fast, efficient, and highly stereoselective epoxidation with H 2O2 is reached by manganese coordination complexes with e-rich aminopyridine tetradentate ligands. It is shown that the electronic properties of these catalysts vary systematically with the stereoselectivity of the O-atom transfer event and exert fine control over the activation of hydrogen peroxide, reducing the amount of carboxylic acid co-catalyst necessary for efficient operation.
- Cusso, Olaf,Garcia-Bosch, Isaac,Font, David,Ribas, Xavi,Lloret-Fillol, Julio,Costas, Miquel
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supporting information
p. 6158 - 6161
(2014/01/17)
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- Highly efficient epoxidation of unsaturated steroids using magnesium bis(monoperoxyphthalate) hexahydrate
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Fast generation of epoxides from the corresponding homoallylic and allylic steroidal olefins was developed by using magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) as oxidant suspended in acetonitrile (CH3CN) at reflux temperature. The protocol involves the use of a safe readily available oxidant along with an easy work-up, which renders the process very efficient. Selective 4,5- and 5,6-epoxidations of steroids are reported. Among them, highly stereoselective epoxidation of Δ5-B-nor-cholestanes was achieved. Moreover, the method is chemoselective for the 5,6-position and can be applied to the epoxidation of ring-A enones.
- Carvalho, Jo?o F.S.,Silva, M. Manuel Cruz,Sá e Melo, M. Luisa
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experimental part
p. 2773 - 2781
(2009/08/15)
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- Synthesis of pregnane derivatives, their cytotoxicity on LNCaP and PC-3 cells, and screening on 5α-reductase inhibitory activity
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A series of epoxy-and/or 20-oxime pregnanes were synthesized from commercially available pregnenolone. Compounds 1, 3, 7, 8 and 11-13 were evaluated for cytotoxicity activity towards LNCaP (androgen-dependent) and PC-3 (androgenindependent) prostate cancer cells. Compound 13 showed the highest activity on both LNCaP (IC50 15.17 μM) and PC-3 (IC50 11.83 μM) cell lines. Compound 11 showed weak activity on LNCaP cells (IC50 71.85 μM) and 8 showed the weak activity on PC-3 cells (IC50 68.95 μM), respectively. The 5α-reductase II (5AR2) inhibitory effects of compounds 1-3, 5 and 7-13 were investigated in a convenient screening model, in which compounds 5, 8, 11 and 12 were observed to be potential inhibitors of 5α-reductase, in particular, the 4-azasteroid 11, that also inhibited cell proliferation of androgen-dependent cells and 8, that in addition inhibited PC-3 cells more potently than LNCaP cells.
- Kim, Sujeong,Ma, Eunsook
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experimental part
p. 4655 - 4668
(2010/04/06)
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- Ring A aromatic steroids in the pregnane series
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4-Methylpregna-1,3,5(10)-trien-20-one and 4-methylpregna-1,3,5(10),16- tetraen-20-one have been obtained by a dienol: benzene type of rearrangement of 5α,6α-epoxypregnanes possessing a further double bond equivalent on ring A. The crystal structure of 4-methyl-19-norpregna-1,3,5(10)-trien-20-one is reported.
- Uyanik, Cavit,Malay, Aslihan,Hanson, James R.,Hitchcock, Peter B.,Tiryakioglu, Serpil
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p. 417 - 419
(2007/10/03)
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- Highly selective lipase-mediated discrimination of diastereomeric 5,6-epoxysteroids
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Stereoisomerically pure 3β-hydroxy-5,6-epoxysteroids were obtained by combining selective chemical methods for α- and β-epoxidation of Δ5-unsaturated steroids with enzymatic stereoselective esterification of the 3β-hydroxyl group. 5β,6β-Epoxy-3β- hydroxysteroids were efficiently acylated by Novozym 435 and lipase AK, whereas 5α,6α-epoxy-3β-hydroxysteroids were good substrates for Candida rugosa lipase. Mild enzymatic deacylation of the 3β-acetoxy group in the presence of the epoxy functionality was also accomplished by C. rugosa lipase-mediated hydrolysis.
- Cruz Silva, M. Manuel,Riva, Sergio,Sa E Melo, M. Luisa
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p. 1173 - 1179
(2007/10/03)
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- The role of metal salts in a solid phase β-selective epoxidation of Δ5-steroids with potassium permanganate
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Epoxidation of Δ5-steroids with a potassium permanganate and a range of metal salts in the solid phase gives the 5β, 6β-epoxides. The results have been rationalised in terms of the oxophilic metal ions favouring epoxide formation in the collapse of a manganate intermediate.
- Salvador, Jorge A.R.,Hanson, James R.
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p. 576 - 578
(2007/10/03)
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- Stereoselective 7α-hydroxylation of 3β-acetoxy-Δ5-steroids by Fe(PA)3/H2O2/MeCN
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Stereoselective 7α-hydroxylation reaction of Δ5-steroids by a Fe(PA; picolinate)3/H2O2/MeCN system is presented. The 7α-hydroxylation reactions were achieved in 33-40% yields by addition of 30%-H2O2 to a solution of 3β-acetoxy-Δ5-steroids 1a-1d and a crystalline of Fe(PA)3 in MeCN.
- Kotani, Eiichi,Takeya, Tetsuya,Egawa, Hirotaka,Tobinaga, Seisho
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p. 750 - 752
(2007/10/03)
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- The Study of Epoxidation of Steroidal Alkenes with Potassium Permanganate-Inorganic Salts
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Copper sulfate could be substituted by other transition metal salts with non-coordinating anions in the β-epoxidation of steroidal alkenes with potassium permanganate-copper sulfate, which suggested the face selectively might result from the initial forma
- Parish, Edward J.,Li, Shengrong
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p. 288 - 289
(2007/10/03)
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- Mercuric Oxide-Iodine Oxidation of 6β-Hydroxypregnanes. Influence of the C-5 Functionality
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Oxidation of 6β-hydroxyprogesterone and 3β-acetoxy-5α,6β-dihydroxypregnan-20-one with mercuric oxide-iodine under photolytic conditions rendered 4α-iodo-5β,6β-oxidopregnan-3,20-dione and 3β-acetoxy-7-iodo-19-formyloxy-5,7-seco-6-norpregnan-5,20-dione respectively. - Keywords: 6β-Hydroxypregnanes, Mercuric Oxide, Oxidation, β-Fragmentation, Hypoiodite Reaction
- Brachet-Cota, Adriana L.,Burton, Gerardo
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p. 491 - 496
(2007/10/02)
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- New Syntheses of 19,21-Dihydropregn-4-ene-3,20-dione, 21-Hydroxy-19-norpregn-4-ene-3,20-dione, and 11β,19,21-trihydroxypregn-4-ene-3,20-dione
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19,21-Dihydroxypregn-4-ene-3,20-dione has been synthesized from 3β-acetoxypregn-5-en-20-one via the "hypoiodite reaction" , and Henbest acetoxylation at C-21; oxidation of the intermediate 21-monoacetate to 19-oxo derivative and alkaline cleavage gave 21-hydroxy-19-norpregn-4-ene-3,20-dione.A similar synthesis of 11β,19,21-trihydroxypregn-4-ene-3,20-dione from 3β-acetoxypregn-5-ene-11,20-dione proceeded through intermediates with the 11β-hydroxy function protected as its acetate.Unusual features mainly of conformational origin were observed in the presence of the 11β-acetoxy substituent; some were helpful to the synthesis, while others led to undesirable side reactions.
- Kirk, David N.,Yeoh, Boon Leng
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p. 2945 - 2952
(2007/10/02)
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