- Selective silylation of alcohols, phenols and oximes using N-chlorosaccharin as an efficient catalyst under mild and solvent-free conditions
-
Efficient silylation of OH group in alcohols, phenols and oximes is described using a catalytic amount of N-chlorosaccharin and hexamethyldisilazane (HMDS) under mild and solvent-free conditions. This silylation reaction can be carried out with excellent and interesting various selectivities.
- Aghapour, Ghasem,Moghaddam, Ali Kazemi,Nadali, Samaneh
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p. 197 - 203
(2015/05/12)
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- Determination of total cholesterol in serum by gas chromatography-mass spectrometry
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In this study, a reliable protocol for determination of total cholesterol in serum using gas chromatography-mass spectrometry was established. The total free cholesterol was extracted from the serum with chloroform and derivatized with bis(trimethylsilyl)trifluoroacetamide, analyzed without the saponification step commonly used. Linear calibration curves of cholesterol were obtained from the concentration 0.1 to 15 mmol L-1. The limit of detection was 0.04 mmol L-1. Finally, the proposed method was to explore the influence of high cholesterol diet on total cholesterol in serum of rats.
- Lian, Kaoqi,Zhang, Pingping,Wang, Wei,Dai, TIngting,Li, Lei
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p. 2646 - 2648
(2014/06/09)
-
- Salt-free preparation of trimethylsilyl ethers by B(C6F 5)3-catalyzed transfer silylation by using a Me 3SiH surrogate
-
An unprecedented transfer silylation of alcohols catalyzed by the strong Lewis acid B(C6F5)3 is described. Gaseous Me3SiH is released in situ by B(C6F5) 3-catalyzed decomposition of 3-trimethylsilylcyclohexa-1,4-diene and subsequently reacts with an alcohol in a dehydrogenative Si-O coupling promoted by the same boron catalyst. Benzene and dihydrogen are formed during the reaction, but no salt waste is. This expedient protocol is applicable to several silicon groups, and the preparation of trimethylsilyl ethers presented here is potentially useful for alcohol derivatization prior to GLC analysis. Copyright
- Simonneau, Antoine,Friebel, Jonas,Oestreich, Martin
-
supporting information
p. 2077 - 2083
(2014/04/17)
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- Highly atom economical uncatalysed and I2-catalysed silylation of phenols, alcohols and carbohydrates, using HMDS under solvent-free reaction conditions (SFRC)
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An uncatalysed silylation of phenols, regardless on the aggregate state and nature of the substituents with 0.55 equiv of HMDS under solvent-free reaction conditions (SFRC) at room temperature is reported. Sterically hindered phenols, carbohydrates and most of the alcohols additionally required a catalytic amount (up to 2 mol %) of iodine. The reaction protocol is very simple; obtaining a pure product, particularly of uncatalysed reactions, was frequently a completely solvent-free process.
- Jereb, Marjan
-
experimental part
p. 3861 - 3867
(2012/06/30)
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- Alum: An efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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A highly convenient method for the trimethylsilylation of alcohols and phenols via treatment by hexamethyldisilazane in the presence of alum as a catalyst has been developed. A wide variety of hydroxyl groups were selectively protected in CH3CN under mild conditions.
- Yang, Xiaojuan,Liang, Jinying
-
experimental part
p. 228 - 230
(2012/08/07)
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- Polyvinylpolypyrrolidoniume tribromide as new and metal-free catalyst for the formylation and trimethylsilylation of hydroxyl group
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Trimethylsilylation of alcohols was achieved using 1,1,1,3,3,3- hexamethyldisilazane (HMDS) as silylating agent, in the presence of polyvinylpolypyrrolidoniume tribromide in acetonitrile at room temperature. Also a variety of alcohols were converted into alkyl formates by ethyl formate and a catalytic amount of polyvinylpolypyrrolidoniume tribromide under solvent free conditions at room temperature.
- Ghorbani-Choghamarani, Arash,Goudarziafshar, Hamid,Zamani, Parisa
-
experimental part
p. 1207 - 1210
(2012/01/05)
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- Protection of hydroxyl groups as a trimethylsilyl ether by 1,1,1,3,3,3-hexamethyldisilazane promoted by aspartic acid as an efficient organocatalyst
-
A wide variety of alcohols and phenols were protected as trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyl disilazane catalyzed by aspartic acid as a non-toxic, metal-free, and green organocatalyst at room temperature in acetonitrile under mild and heterogeneous conditions. The procedure is operationally simple and the silylated product was obtained in high yield and purity.
- Ghorbani-Choghamarani, Arash,Norouzi, Masoomeh
-
scheme or table
p. 595 - 598
(2012/01/06)
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- Melamine-trisulfonic-acid-catalyzed trimethylsilylation of alcohols and phenols
-
A highly convenient method for the trimethylsilylation of alcohols and phenols via treatment by hexamethyldisilazane in the presence ofmelamine trisulfonic acid as a catalyst has been developed. A wide variety of hydroxyl groups were selectively protected under solvent-free conditions. Copyright Taylor & Francis Group, LLC.
- Wu, Liqiang,Sun, Pengli,Yan, Fulin
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experimental part
p. 2055 - 2060
(2011/11/30)
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- Chemoselective and catalytic trimethylsilylation of alcohols and phenols by 1,1,1,3,3,3-hexamethyldisilazane and catalytic amounts of PhMe 3N+Br3-
-
An efficient procedure for the trimethylsilylation of alcohols and phenols is presented. The combination of 1,1,1,3,3,3-hexamethyldisilazane and a catalytic amount of phenyltrimethylammonium tribromide (PhMe3N +Br3-) was found to be effective for the trimethylsilylation of alcohols and phenols. The protection reaction is very simple and homogenously performed in dichloromethane at room temperature and mild conditions.
- Ghorbani-Choghamarani, Arash,Cheraghi-Fathabad, Nasrin
-
experimental part
p. 1103 - 1106
(2010/12/25)
-
- Nutritional traits of bean (Phaseolus vulgaris) seeds from plants chronically exposed to ozone pollution
-
The effect of chronic exposure to ozone pollution on nutritional traits of bean (Phaseolus vulgaris L. cv. Borlotto Nano Lingua di Fuoco) seeds from plants grown in filtered and nonfiltered open-top chambers (OTCs) has been investigated. Results showed th
- Iriti, Marcello,Di Maro, Antimo,Bernasconi, Silvana,Burlini, Nedda,Simonetti, Paolo,Picchi, Valentina,Panigada, Cinzia,Gerosa, Giacomo,Parente, Augusto,Faoro, Franco
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supporting information; experimental part
p. 201 - 208
(2009/05/31)
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- The ratio of cholesterol 5,6-secosterols formed from ozone and singlet oxygen offers insight into the oxidation of cholesterol in vivo
-
Ongoing efforts to unravel the origins of the cholesterol 5,6-secosterols (1a and 1b) in biological systems have revealed that the two known chemical routes to these oxysterols, ozonolysis of cholesterol (3) and Hock-cleavage of 5-α-hydroperoxycholesterol (4a), are distinguishable based upon the ratio of the hydrazone derivatives (2a and 2b) formed in each case and this ratio offers an insight into the chemical origin of the secosterols in vivo. The Royal Society of Chemistry 2009.
- Wentworth, Anita D.,Song, Byeong-Doo,Nieva, Jorge,Shafton, Asher,Tripurenani, Sangeetha,Wentworth Jr., Paul
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supporting information; experimental part
p. 3098 - 3100
(2009/12/01)
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- 1,3-Dichloro-5,5-dimethylhydantoin (DCH) and trichloromelamine (TCM) as efficient catalysts for the chemoselective trimethylsilylation of hydroxyl group with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) under mild conditions
-
A highly convenient method for the trimethylsilylation of alcohols and phenols via treatment by hexamethyldisilazane in the presence of 1,3-dichloro-5,5-dimethylhydantoin (DCH) and/or trichloromelamine (TCM) as a catalyst has been developed. A wide variety of hydroxyl groups were selectively protected in CH2Cl2/CH3CN under mild conditions.
- Ghorbani-Choghamarani, Arash,Amani, Kamal,Zolfigol, Mohammad Ali,Hajjami, Maryam,Ayazi-Nasrabadi, Roia
-
experimental part
p. 255 - 260
(2009/12/06)
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- Highly efficient chemo- and regioselective silylation of -OH groups and cyanosilylation of aldehydes promoted by TiCl2(OTf)-SiO2 as a new recyclable catalyst
-
TiCl2(OTf)-SiO2 as an easy handling recyclable catalyst was applied for trimethylsilylation of diethyl α-hydroxyphosphonates, alcohols and phenols with high selectivity using HMDS as a silylating agent. Cyanotrimethylsilyl ethers were also obtained in excellent yields from treatment of aldehydes with TMSCN in the presence of this catalyst.
- Firouzabadi, Habib,Iranpoor, Nasser,Farahi, Soghra
-
scheme or table
p. 3923 - 3928
(2010/02/28)
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- Silica-supported ferric chloride (silica-FeCl3): A reusable, easily controllable catalyst for the protection of hydroxyl groups under mild and ambient conditions
-
Diverse alcohols, phenols, and naphthols were converted into their corresponding trimethylsilyl ether effectively with hexamethyldisilazane in the presence of silica-FeCl3 under solvent-free and ambient conditions with short reaction time in good to excellent yields. Work up procedure is easy, and the catalyst can be recovered by simple filtration and reused. Copyright Taylor & Francis Group, LLC.
- Shaterian, Hamid Reza,Ghashang, Majid,Hosseinian, Asghar
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experimental part
p. 2108 - 2118
(2009/07/18)
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- A highly efficient method for the silylation of alcohols, phenols, and naphthols using HMDS in the presence of zinc oxide (ZnO) as economical heterogeneous catalyst
-
Variety alcohols, phenols, and naphthols were effectively converted into their corresponding trimethylsilyl ether with hexamethyldisilazane in the presence of zinc oxide under very mild and ambient conditions with short reaction time in good to excellent yields.
- Shaterian, Hamid Reza,Ghashang, Majid
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p. 194 - 204
(2008/12/21)
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- Alumina sulfuric acid as an efficient and recyclable heterogeneous catalyst for the O-silylation of alcohols, phenols, and oximes
-
Alumina sulfuric acid as a recyclable catalyst conducts the transformation of various types of alcohol, phenols, and oximes with hexamethyldisilazane (HMDS) to the corresponding O-trimethylsilylated compounds in good to excellent yields under mild and ambient conditions with short reaction times. The method is highly selective for the conversion of primary alcohols in the presence of secondary and tertiary alcohols. Additionally, the catalyst can be easily recovered and reused at least eight times without detectable loss of reactivity.
- Shaterian, Hamid Reza,Khorami, Fahimeh,Amirzadeh, Azita,Ghashang, Majid,Hosseinian, Asghar
-
scheme or table
p. 2584 - 2595
(2009/08/15)
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- A mild, simple, efficient, and selective protection of hydroxyl groups using silica-supported sodium hydrogen sulfate as a heterogeneous catalyst
-
A mild, simple, novel, and highly efficient method for the rapid protection of various primary, secondary, tertiary aliphatic alcohols, aromatic alcohols, and oximes using hexamethyldisilazane (HMDS) in the presence of silica-supported sodium hydrogen sulfate (NaHSO4-SiO2), as an active, inexpensive, nontoxic, heterogeneous, and readily available catalyst under ambient conditions is described. Timethylsilyl ethers were prepared in high to excellent yields, with short reaction times under mild and almost neutral reaction conditions at room temperature. Copyright Taylor & Francis Group, LLC.
- Shaterian, Hamid Reza,Doostmohammadi, Razieh,Ghashang, Majid,Rahmani, Mashaallah
-
experimental part
p. 3127 - 3135
(2009/09/25)
-
- Trimethylsilylation of hydroxyl group with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) catalyzed by tribromomelamine (TBM)
-
Tribromomelamine (TBM) can be used as a novel catalyst for the trimethylsilylation of alcohols and phenols with 1,1,1,3,3,3- hexamethyldisilazane (HMDS). A wide variety of hydroxyl groups were selectively protected in CH2Cl2/CH3CN under mild conditions.
- Ghorbani-Choghamarani, Arash,Zolfigol, Mohammad Ali,Hajjami, Maryam,Jafari, Shila
-
experimental part
p. 1208 - 1213
(2010/01/07)
-
- Alumina perchloric acid (Al2O3-HClO4) as an efficient heterogeneous catalyst for modified preparation of trimethylsilyl ethers
-
A highly efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, benzylic, secondary, hindered secondary, tertiary, phenols, and oximes with hexamethyldisilazane (HMDS) using alumina perchloric acid (Al2O3-HClO4) as recyclable heterogeneous catalyst in excellent yields with short reaction times (3-65 min) under ambient conditions is described. Copyright Taylor & Francis Group, LLC.
- Shaterian, Hamid Reza,Khorami, Fahimeh,Amirzadeh, Azita,Ghashang, Majid
-
experimental part
p. 2865 - 2874
(2009/09/25)
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- Fe(HSO4)3 promoted trimethylsilylation of alcohols and phenols in solution and under solvent-free conditions
-
Alcohols and phenols are efficiently converted to their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of Fe(HSO4)3 in solution and under solvent-free conditions.
- Shirini, Farhad,Zolfigol, Mohammad A.,Abri, Abdol-Reza
-
-
- Facile method for trimethylsilylation of alcohols using hexamethyldisilazane and ammonium thiocyanate under neutral conditions
-
A highly efficient method for trimethylsilylation of primary, secondary, tertiary, allylic, and a variety of sugar-derived alcohols using hexamethyldisilazane in the presence of a catalytic amount of ammonium thiocyanate under neutral conditions is reported. Copyright Taylor & Francis Group, LLC.
- Jadhav, Vrushali H.,Kumar, K. S. Ajish,Chaudhari, Vinod D.,Dhavale, Dilip D.
-
p. 1363 - 1370
(2008/02/01)
-
- Palladium-catalyzed silylation of alcohols with hexamethyldisilane
-
The combination of hexamethyldisilane and a catalytic amount of [PdCl(η3-C3H5)]2-PPh 3 was found to be effective for the trimethylsilylation of alcohols, where both of the two trimethylsilyl groups of hexamethyldisilane were transferred to alcohols without coproduction of any stoichiometric amount of byproduct but H2. The Royal Society of Chemistry 2006.
- Shirakawa, Eiji,Hironaka, Koji,Otsuka, Hidehito,Hayashi, Tamio
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p. 3927 - 3929
(2007/10/03)
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- Silica sulfate, an efficient catalyst for the trimethylsilylation of alcohols
-
An easy method for the preparation of trimethylsilyl ethers from alcohols and 1,1,1,3,3,3-hexamethyl-disilazane (HMDS) using silica sulfate as a catalyst under mild conditions in excellent yields is described. Copyright Taylor & Francis Group, LLC.
- Jin, Tong-Shou,Tian, Ruo-Fei,Liu, Li-Bin,Zhao, Ying,Li, Tong-Shuang
-
p. 1823 - 1828
(2007/10/03)
-
- THERAPEUTIC PROCEDURES
-
As illustrated herein, cholesterol is oxidized when it is present in atherosclerotic plaques. This reaction generates cytotoxic cholesterol oxidation or ozonation products. The present application is directed to the products of cholesterol ozonation, binding entities directed against such products, and methods of using such binding entities and cytotoxins to treat a variety of diseases.
- -
-
Page/Page column 117-118
(2008/06/13)
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- DETECTION OF CHOLESTEROL OZONATION PRODUCTS
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The invention relates to detection of cholesterol ozonation products that are generated by atherosclerotic plaque material, and to methods of detecting vascular conditions that relate to the accumulation and oxidation of cholesterol.
- -
-
Page/Page column 100
(2008/06/13)
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- Silylation and tetrahydropyranylation of alcohols catalyzed by Al(HSO 4)3
-
Trimethylsilylation and tetrahydropyranylation of alcohols are efficiently catalyzed by Al(HSO4)3. All reactions were performed under mild and completely heterogeneous conditions in good-to-high yields.
- Shirini, Farhad,Zolfigol, Mohammad Ali,Abedini, Masoumeh
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p. 1982 - 1985
(2007/10/03)
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- Magnesium triflate [Mg(OTf)2] a highly stable, non-hygroscopic and a recyclable catalyst for the high yielding preparation of diethyl α-trimethylsilyloxyphosphonates from diethyl α-hydroxyphosphonates by HMDS under solventless conditions
-
A broad, adaptable, high yielding and convenient procedure for the easy conversion of various α-hydroxyphosphonates to α-trimethylsilyloxyphosphonates under mild conditions with HMDS in the presence of a catalytic amount of magnesium triflate as a highly stable and a non-hygroscopic recyclable catalyst in neat conditions is described. In order to show the general applicability of this method, we have also applied this procedure successfully for the silylation of ordinary alcohols and phenols.
- Firouzabadi, Habib,Iranpoor, Nasser,Sobhani, Sara,Ghassamipour, Soheila
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p. 3197 - 3202
(2007/10/03)
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- A Convenient Method for Protection and Deprotection of Alcohols and Phenols as Alkylsilyl Ethers Catalyzed by Iodine under Microwave Irradiation
-
Irradiation of alcohols or phenols with tert-butyldimethylsilyl chloride (TBDMSCl) or trimethylsilyl chloride (TMSCl) in presence of catalytic amount (20 mol%) of iodine in a microwave oven for 2 min gives the corresponding silyl ethers in excellent yield. Iodine in methanol deprotects the silyl ether into its parent alcohol or phenol under similar reaction conditions.
- Saxena, Ira,Deka, Nabajyoti,Sarma, Jadab C.,Tsuboi, Sadao
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p. 4185 - 4191
(2007/10/03)
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- Sulfuric acid supported on silica gel: An efficient catalyst for silylation of hydroxyl groups with HMDS and their convenient deprotection under non-aqueous condition
-
A mild and efficient silylation of alcohols and phenols with hexamethyl-disilazane(HMDS) and convenient desilylation of the corresponding silyl ethers are achieved using a catalytic amount of H2SO4 SiO2 under non-aqueous condition. In this work chemoselective silylation of hydroxy compounds in the presence of thiols and amines is conducted.
- Lakouraj,Akbari
-
p. 1165 - 1167
(2007/10/03)
-
- Phosphomolybdic acid, an efficient catalyst for the trimethylsilylation of alcohols
-
An easy method for the preparation of trimethylsilyl ethers of alcohols with 1,1,1,3,3,3-hexamethyl- disilazane (HMDS) catalysed by phosphomolybdic acid (PMA) under mild conditions has been carried out in excellent yields.
- Jin, Tong-Shou,Li, Yan-Wei,Sun, Guang,Li, Tong-Shuang
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p. 456 - 458
(2007/10/03)
-
- Heterogeneous catalysis in trimethylsilylation of alcohols and phenols by zirconium sulfophenyl phosphonate
-
Layered zirconium sulfophenyl phosphonate was found to be an efficient heterogeneous catalyst for the trimethylsilylation of alcohols and phenols.
- Curini, Massimo,Epifano, Francesco,Marcotullio, Maria Carla,Rosati, Ornelio,Costantino, Umberto
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p. 541 - 546
(2007/10/03)
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- Montmorillonite clay catalysis XI1: Protection and deprotection of hydroxyl group by formation and cleavage of trimethylsilyl ethers catalysed by catalysed by montmorillonite K-10
-
An easy preparation of trimethylsilyl ethers of alcohols and phenols with 1,1,1,3,3,3-hexamethyldisilazane(HMDS) catalysed by montmorillonite K- 10 at room temperature has been carried out in excellent yields. Desilyation of trimeylsilyl ethers is catalysed by K-10 in methanol at ambient temperature in high yields.
- Zhang, Zhan-Hui,Li, Tong-Shuang,Yang, Feng,Fu, Cheng-Guang
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p. 3105 - 3114
(2007/10/03)
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- Trimethylsilyl chloride-accelerated reduction and pinacol coupling of carbonyl compounds by means of samarium diiodide
-
The combination of samarium diiodide (SmI2) and trimethylsilyl chloride (Me3SiCl) in THF-HMPA is found to accelerate the reduction of sterically hindered and enolisable ketones, and also to accelerate pinacolisation of the carbonyl compounds depending on the reaction conditions.
- Honda, Toshio,Katoh, Miho
-
p. 369 - 370
(2007/10/03)
-
- The mechanisms of the rearrangements of allylic hydroperoxides: 5α-hydroperoxy-3β-hydroxycholest-6-ene and 7α-hydroperoxy- 3β-hydroxycholest-5-ene
-
The rearrangement of 5α-hydroperoxy-3β-hydroxycholest-6-ene in solution under 18O2, gives isotopically normal 7α-hydroperoxy-3β-hydroxycholest-5-ene, whereas the epimerization of this product to give 7β-hydroperoxy-3β-hydroxycholest-5-ene involves incorporation of 73-83% of 18O2 into the hydroperoxy group. These two reactions proceed through the corresponding hydroperoxyl radicals, which have different e.s.r. spectra and which therefore must exist as separate and distinct species. The former reaction shows a first-order dependence on hydroperoxide concentration, and a half-order dependence on t-butyl hyponitrite which was added as an initiator. It is suggested that the first reaction involves a sigmatropic [2,3]-rearrangement, whereas the second reaction proceeds through a dissociative mechanism.
- Beckwith, Athelstan L. J.,Davies, Alwyn G.,Davison, Ian G. E.,Maccoll, Allan,Mruzek, Margaret H.
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p. 815 - 824
(2007/10/02)
-
- SATURATED AND UNSATURATED STEROLS OF NITROGEN-FIXING BLUE-GREEN ALGAE (CYANOBACTERIA)
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Five species of filamentous nitrogen-fixing blue-green algae (Cyanobacteria), (Anabaena cylindrica, Anabaena solitaria, Anabaena viguieri, Nostoc carneum, Nodularia harveyana) were grown in a freshwater medium containing 10percent seawater(DS medium).The sterols were analysed by means of a newly developed procedure involving precipitation with digitonine, GC and GC/MS but not TLC and CC.All species were found to synthesize a great variety of sterols (11-15 compounds).The digitonin precipitable sterols made up ca 0.005-0.03percent of the dried algal biomass.Remarkably, each species produced the saturated sterols, 5α-cholestan-3β-ol, 24-methyl-5α-cholestan-3β-ol and 24-ethyl-5α-cholestan-3β-ol.The latter was the main sterol in all organisms.Furthermore, the investigated microalgae were found to synthesize known C27, C28 and C29 sterols.Key Word Index-blue-green algae; nitrogen-fixing blue-green algae; sterols; cyanobacteria.
- Kohlhase, Manfred,Pohl, Peter
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p. 1735 - 1740
(2007/10/02)
-
- THE EFFECT OF MERCURY AND CADMIUM ON THE FATTY ACID AND STEROL COMPOSITION OF THE MARINE DIATOM ASTERIONELLA GLACIALIS
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Key Word Index - Asterionella glacialis; diatom; sterols; lipids; fatty acids; mercury; cadmium.Cells of the marine diatom Asterionella glacialis treated with the organomercurial p-chloromercuribenzoate (PCMB) and cadmium, at growth retarding concentrations, exhibit decreased total fatty acid, polyunsaturated fatty acid and sterol contents.The level of individual fatty acids and sterols was also affected by metal treatment with significant decreases in the major polyunsaturated fatty acids 20:5Δ5,8,11,14,17, 16:1Δ9 and 16:3Δ3,6,9 in PCMB-treated, and 20:5Δ5,8,11,14,17 in cadmium-treated cells; increased cholest-5-en-3β-ol, particularly in PCMB-treated cells; and a decrease in the ratio of 24-ethylcholest-5-en-3β-ol to 24-ethylcholesta-5,24(28)Z-dien-3β-ol which was most notable in cadmium-treated cells.These results can be explained in terms of the formation of mercury and cadmium complexes with thiol-containing enzymes involved in lipid biosynthesis and metabolism, and thus provide further support for the hypothesis that transition metal toxicity is mediated by metal inactivation of physiologically essential, thiol-containing enzymes and co-factors.
- Jones, Gary J.,Nichols, Peter D.,Johns, R. B.,Smith, J. David
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p. 1343 - 1348
(2007/10/02)
-