1256-31-1Relevant academic research and scientific papers
Synthetic study of strongylophorines: stereoselective construction of the characteristic lactone bridge
Oikawa, Yuya,Uchiyama, Daiki,Shirasawa, Takuya,Oikawa, Masato,Ishikawa, Yuichi
, p. 3949 - 3951 (2016)
Herein, we report an efficient construction of the lactone bridge of strongylophorine-2, which is a meroditerpenoid isolated from Strongylophora durissima and an inhibitor for HIF-1 transcriptional pathway. Starting from dehydroepiandrosterone acetate, the characteristic lactone has been constructed in 5.4% over 18 steps by employing, (1) modified oxy radical-mediated C–H functionalization at the C24 methyl group, and (2) four-step manipulation of C4 quaternary carbon stereogenic center. The lactone synthesized here is expected as a precursor for (8-desmethyl)strongylophorine-2 which is of particular interest in terms of structure–activity relationships in the inhibition of HIF-1 transcriptional pathway.
Efficient chemoenzymatic synthesis, cytotoxic evaluation, and SAR of epoxysterols
Carvalho, Jo?o F. S.,Cruz Silva, M. Manuel,Moreira, Jo?o N.,Sim?es, Sérgio,Sá E Melo, M. Luisa
experimental part, p. 4007 - 4019 (2009/12/26)
A library of diastereomerically pure epoxysterols, prepared by combining chemical and enzymatic methodologies, was evaluated for cytotoxicity toward human cancer and noncancer cell lines. Unsaturated steroids were oxidized by magnesium bis(monoperoxyphthalate) hexahydrate in acetonitrile, and the resulting epimeric epoxides were enzymatically separated using Novozym 435 or lipase AY. Some of the synthesized epoxysterols have potent cytotoxicity and higher activity on cancer cell lines HT29 and LAMA-84.
Highly selective lipase-mediated discrimination of diastereomeric 5,6-epoxysteroids
Cruz Silva, M. Manuel,Riva, Sergio,Sa E Melo, M. Luisa
, p. 1173 - 1179 (2007/10/03)
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.
A new electrochemical system for stereoselective allylic hydroxylation of cholesteryl acetate with dioxygen induced by iron picolinate complexes
Okamoto, Iwao,Funaki, Wataru,Nakaya, Kyosuke,Kotani, Eiichi,Takeya, Tetsuya
, p. 756 - 759 (2007/10/03)
The oxygenation reaction of cholesteryl acetate 1 was examined with the FeIII(PA)3/O2/MeCN system using an electrochemical method. The constant potential technique gave mainly the 7-hydroxylated product stereoselectively, along with the 7-oxo product. This oxygenation system is mechanistically unique, requiring iron catalyst, dioxygen, and both cathode and anode.
Sterol synthesis. Preparation and characterization of fluorinated and deuterated analogs of oxygenated derivatives of cholesterol
Li, Shengrong,Pang, Jihai,Wilson, William K.,Schroepfer Jr., George J.
, p. 33 - 71 (2007/10/03)
Oxygenated sterols, including both autoxidation products and sterol metabolites, have many important biological activities. Identification and quantitation of oxysterols by chromatographic and spectroscopic methods is greatly facilitated by the availability of authentic standards, and deuterated and fluorinated analogs are valuable as internal standards for quantitation. We describe the preparation, purification and characterization of 43 oxygenated sterols, including the 4β-hydroxy, 7α-hydroxy, 7β-hydroxy, 7-keto, and 19-hydroxy derivatives of cholesterol and their analogs with 25,26,26,26,27,27,27-heptafluoro (F7) and 26,26,26,27,27,27-hexadeuterio (d6) substitution. The 7α-hydroxy, 7β-hydroxy, and 7-keto derivatives of (25R)-cholest-5-ene-3β,26-diol (1d) and their 16,16-dideuterio analogs were also prepared. These d2-26-hydroxysterols and [16,16-2H2]-(25R)-cholest-5-ene-3β,26-diol (1e) were synthesized from [16,16-2H2]-(25R)-cholest-5-ene-3β,26-diol diacetate (2e), which can be prepared from diosgenin. The highly specific deuterium incorporation at C-16 in 1e and 2e should be useful in mass spectral analysis of 26-hydroxycholesterol samples by isotope dilution methods. The Δ5-3β,7α,26- and Δ5-3β,7β,26-triols were regioselectively oxidized/isomerized to the corresponding Δ4-3-ketosteroids with cholesterol oxidase. Also described are 5,6α-epoxy-5α-cholestan-3β-ol, its 5β,6β-isomer, cholestane-3β,5α,6β-triol, their F7 and d6 derivatives, and d3-25-hydroxycholesterol, which was prepared from 3β-acetoxy-27-norcholest-5-en-25-one (30). The 43 oxysterols and most synthetic intermediates were isolated in high purity and characterized by chromatographic and spectroscopic methods, including mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. Detailed mass spectral assignments are presented, and 1H NMR stereochemical assignments are derived for the C-19 protons of 19-hydroxysterols and for the side chain protons of 30. Copyright (C) 1999 Elsevier Science Ireland Ltd.
Iron(III)picolinate-catalyzed oxygenation of cholesteryl acetate with hydrogen peroxide or peracetic acid
Takeya, Tetsuya,Egawa, Hirotaka,Inoue, Natsu,Miyamoto, Akiko,Chuma, Toichiro,Kotani, Eiichi
, p. 64 - 70 (2007/10/03)
The reaction of cholesteryl acetate 1 with a Fe(III)(PA; picolinate)3/H2O2/MeCN system (reagent system A), a simple model system for mono-oxygenases, gave mainly the 7α-hydroxylation product 2a, along with 7-ketonization product 3 and the 5,6-epoxidation product 4. On the other hand, reaction of 1 using a Fe(PA)3/peracetic acid (AcOOH)/MeCN system (reagent system c) or a Fe(III)(ClO4)3 · 9H2O-picolinic acid(PAH)- pyridine(Py)/AcOOH/MeCN system (reagent system F), provided 4 predominantly without formation of 2a. The former reaction may proceed via the dimeric Fe(III)-Fe(V) manifold complex, (PAH)(PA)2Fe(III)-O-O-Fe(V)=O(PA)2 (VII) as a hypothetically active species and a nonradical pathway, and the latter may proceed through monomeric iron complexes, [(PAH)(PA)2Fe(V)=O]+ (IX) and [(PAH)(PA)2Fe(V)(OH)(OOH)I+ (X).
Stereoselective 7α-hydroxylation of 3β-acetoxy-Δ5-steroids by Fe(PA)3/H2O2/MeCN
Kotani, Eiichi,Takeya, Tetsuya,Egawa, Hirotaka,Tobinaga, Seisho
, p. 750 - 752 (2007/10/03)
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.
Epoxidation of 2β-Acetoxycholest-5-ene with Cumene Hydroperoxide catalysed by 5,10,15,20-Tetraarylporphyrinatoiron(III) Chlorides
Chauhan,Ray,Mohibb,Azam,Parkash, Som,Sharma
, p. 199 - 201 (2007/10/03)
The reaction of 3β-acetoxycholest-5-ene (1) with cumene hydroperoxide catalysed by electron-withdrawing and perchlorinated 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides (2a-e) form 3β-acetoxy-5α,6α-epoxychoiestane (3), 3β-acetoxy-5β,6β-epoxycholestane (4), 3β-acetoxy-7α-hydroxycholest-5-ene (5), 3β-acetoxy-7β-hydroxycholest-5-ene (6) and 3β-acetoxy-7-oxocholest-5-ene (7) in different yields depending on the reaction conditions. The higher yields of 5β,6β-epoxides (4) have been obtained with 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetraarylporphyrinatoirn(III) chloride (2e) as catalyst than the corresponding 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides (2a-d).
5β,6β-Epoxidation of 3β-Cholesteryl Acetate and its Analogues
Galagovsky, L. R.,Burton, G.,Gros, E. G.
, p. 806 - 810 (2007/10/02)
The treatment of acetylated Δ5-steroids with chromyl diacetate at low temperature afforded the 5β,6β-epoxy derivatives with stereoselectivity greater than 90 per cent. - keywords: Cholesterol, Sitosterol, Campesterol, Stigmasterol, Pregnenolone, Stereoselective Epoxidation
