- Use of Silylated Formiates as Hydrosilane Equivalents
-
The present invention relates to a method for preparing organic compounds of formula (I) by reaction between a silylated formiate of formula (II) and an organic compound in the presence of a catalyst and optionally of an additive. The invention also relates to use of the method for preparing organic compounds of formula (I) for the preparation of reagents for fine chemistry and for heavy chemistry, as well as in the production of vitamins, pharmaceutical products, adhesives, acrylic fibres, synthetic leathers, and pesticides.
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-
Paragraph 0514
(2021/09/26)
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- Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
-
The regioselectivity of hydroxyl radical addition to arenes was studied using a novel analytical method capable of trapping radicals formed after the first elementary step of reaction, without alteration of the product distributions by secondary oxidation processes. Product analyses of these reactions indicate a preference for o- over p-substitution for electron donating groups, with both favored over m-addition. The observed distributions are qualitatively similar to those observed for the addition of other carbon-centered radicals, although the magnitude of the regioselectivity observed is greater for hydroxyl. The data, reproduced by high accuracy CBS-QB3 computational methods, indicate that both polar and radical stabilization effects play a role in the observed regioselectivities. The application and potential limitations of the analytical method used are discussed.
- Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
-
p. 3260 - 3269
(2019/03/11)
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- Activation of hexamethyldisilazane (HMDS) by TiO2 nanoparticles for protection of alcohols and phenols: the effect of the catalyst phase on catalytic activity
-
Anatase TiO2 nanoparticles (TiO2 NPs) were synthesized by the sol–gel method using titanium tetra-isopropoxide (TTIP), isopropyl alcohol, and distilled water and then calcined at 400?°C for 3?h. X-ray diffraction and scanning electron microscopy methods, and Fourier transform infrared spectroscopy were used for characterization of the obtained TiO2 NPs. The obtained anatase TiO2 NPs were used as heterogeneous catalyst for trimethylsilation of various alcohols or phenols with hexamethyldisilazane (HMDS) in CH3CN at room temperature. High to quantitative yields of the products were obtained within short reaction times at room temperature using a very low loading of pure TiO2 NPs without any post-modification with Bronsted or Lewis acid species such as ClSO3H or HClO4. The catalyst can be recycled at least three times without significant loss of its activity. The results of this study provide evidence that the pure anatase phase of TiO2 exhibits higher catalytic activity in terms of catalyst loading and required reaction time compared to a mixture of anatase and rutile phases found in the commercial samples for trimethylsilation of various alcohols or phenols with HMDS.
- Azad, Alireza,Dekamin, Mohammad G.,Afshar, Shahrara,Tadjarodi, Azadeh,Mollahosseini, Afsaneh
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p. 2951 - 2963
(2018/04/11)
-
- Application of a novel nano-immobilization of ionic liquid on an MCM-41 system for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
-
3-[(3-(Trisilyloxy)propyl)chloride]-1-methylimidazolium tribromide ionic liquid supported on MCM-41 [nano-MCM-41@(CH2)3-1-methylimidazole]Br3 as a novel heterogeneous nano-catalyst was easily prepared and characterized usi
- Zolfigol, Mohammad Ali,Sajjadifar, Sami,Ghorbani-Choghamarani, Arash,Tami, Farzaneh
-
p. 7093 - 7106
(2018/08/17)
-
- Magnetic nanoparticle-supported DABCO tribromide: A versatile nanocatalyst for the synthesis of quinazolinones and benzimidazoles and protection/deprotection of hydroxyl groups
-
1,4-Diazabicyclo[2.2.2]octane tribromide supported on magnetic Fe3O4 nanoparticles (MNPs-DABCO tribromide) as a novel heterogeneous tribromide type compound was found to be an efficient and reusable nanocatalyst for the one-pot synthesis of 2-arylquinazolin-4(3H)-ones and 2-aryl-1H-benzo[d]imidazoles through oxidative cyclization of aldehydes with 2-aminobenzamides and 1,2-phenylenediamine, respectively. Also, MNPs-DABCO tribromide catalyzed trimethylsilylation/tetrahydropyranylation and desilylation/depyranylation of a wide variety of alcohols and phenols through changing the solvent medium at room temperature.
- Rostami, Amin,Pourshiani, Omid,Navasi, Yahya,Darvishi, Neda,Saadati, Shaghayegh
-
p. 9033 - 9040
(2017/08/29)
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- Silylation of O-H bonds by catalytic dehydrogenative and decarboxylative coupling of alcohols with silyl formates
-
The silylation of O-H bonds is a useful methodology in organic synthesis and materials science. While this transformation is commonly achieved by reacting alcohols with reactive chlorosilanes or hydrosilanes, we show herein for the first time that silylformates HCO2SiR3 are efficient silylating agents for alcohols, in the presence of a ruthenium molecular catalyst.
- Chauvier, Clément,Godou, Timothé,Cantat, Thibault
-
supporting information
p. 11697 - 11700
(2017/11/03)
-
- TENOFOVIR PRODRUG AND PHARMACEUTICAL USES THEREOF
-
The invention relates to a tenofovir prodrug and pharmaceutical uses thereof. In particular, the invention relates to a compound as shown in general formula (I) and its isomer, pharmaceutically acceptable salt, hydrate or solvate, as well as their uses in
- -
-
Paragraph 0036
(2015/07/15)
-
- 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
-
p. 197 - 203
(2015/05/12)
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- Polystyrene-gallium trichloride complex: A mild, highly efficient, and recyclable polymeric lewis acid catalyst for chemoselective silylation of alcohols and phenols with hexamethyldisilazane
-
Polystyrene-supported gallium trichloride (PS/GaCl3) as a highly active and reusable heterogeneous Lewis acid effectively activates hexamethyldisilazane (HMDS) for the efficient silylation of alcohols and phenols at room temperature. In this he
- Rahmatpour, Ali,Vakili, Ali,Azizian, Setare
-
p. 443 - 451
(2013/12/04)
-
- Br?nsted acid-controlled [3 + 2] coupling reaction of quinone monoacetals with alkene nucleophiles: A catalytic system of perfluorinated acids and hydrogen bond donor for the construction of benzofurans
-
We have developed an efficient Br?nsted acid-controlled strategy for the [3 + 2] coupling reaction of quinone monoacetals (QMAs) with nucleophilic alkenes, which is triggered by the particular use of a specific acid promoter, perfluorinated acid, and a solvent, fluoroalcohol. This new coupling reaction smoothly proceeded with high regiospecificity in regard with QMAs for introducing π-nucleophiles to only the carbon α to the carbonyl group, thereby providing diverse dihydrobenzofurans and derivatives with high yields, up to quantitative, under mild conditions in short reaction times. The choice of Br?nsted acid enabled us to avoid hydrolysis of the QMAs, which gives quinones, and the formation of discrete cationic species from the QMAs. Notably, further investigations in this study with regard to the acid have led to the findings that the originally stoichiometrically used acid could be reduced to a catalytic amount of 5 mol % loading or less and that the stoichiometry of the alkenes could be significantly improved down to only 1.2 equiv. The facts that only a minimal loading (5 mol %) of perfluoroterephthalic acid is required, readily available substrates can be used, and the regioselectivity can be controlled by the acid used make this coupling reaction very fascinating from a practical viewpoint.
- Hu, Yinjun,Kamitanaka, Tohru,Mishima, Yusuke,Dohi, Toshifumi,Kita, Yasuyuki
-
p. 5530 - 5543
(2013/07/26)
-
- Alum: An efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane
-
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)
-
- Highly atom economical uncatalysed and I2-catalysed silylation of phenols, alcohols and carbohydrates, using HMDS under solvent-free reaction conditions (SFRC)
-
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)
-
- P2O5/SiO2 as an efficient and mild catalyst for trimethylsilylation of alcohols using hexamethyldisilazane
-
The protection of alcohols with hexamethyldisilazane (HMDS) in the presence of P2O5/SiO2 at very mild and ambient condition with short reaction times is accomplished in excellent yields. P 2O5/SiOsub
- Eshghi, Hossein,Rahimizadeh, Mohammad,Ghadamyari, Zohreh,Shiri, Ali
-
p. 1435 - 1439
(2013/02/22)
-
- The effect of solvent accessible surface on Hammett-type dependencies of infinite dilution 29Si and 13C NMR shifts in ring substituted silylated phenols dissolved in chloroform and acetone
-
Infinite dilution 29Si and 13C NMR chemical shifts were determined from concentration dependencies of the shifts in dilute chloroform and acetone solutions of para substituted O-silylated phenols, 4-R-C6H4-O-SiR′2R″ (R = Me, MeO, H, F, Cl, NMe2, NH2, and CF3), where the silyl part included groups of different sizes: dimethylsilyl (R′ = Me, R″ = H), trimethylsilyl (R′ = R″ = Me), tert-butyldimethylsilyl (R′ = Me, R″ = CMe3), and tert-butyldiphenylsilyl (R′ = C6H5, R″ = CMe3). Dependencies of silicon and C-1 carbon chemical shifts on Hammett substituent constants are discussed. It is shown that the substituent sensitivity of these chemical shifts is reduced by association with chloroform, the reduction being proportional to the solvent accessible surface of the oxygen atom in the Si-O-C link. Copyright
- Blechta, Vratislav,Sabata, Stanislav,Sykora, Jan,Hetflejs, Jiri,Soukupova, Ludmila,Schraml, Jan
-
experimental part
p. 128 - 134
(2012/08/07)
-
- Rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalysed by in situ generated I2 using Oxone /KI or cerium ammonium nitrate (CAN)/KI systems under mild conditions
-
Structurally diverse alcohols and phenols were trimethylsilylated in clean and efficient reactions with hexamethyldisilazane (HMDS) in the presence of a catalytic amount of I2 generated in situ from Oxone /KI or CAN/KI systems. The reactions occur rapidly in good to high yields in wet CH2Cl2 at room temperature. Indian Academy of Sciences.
- Kolvari, Eskandar,Khazaei, Ardeshir,Zolfigol, Mohammad Ali,Koukabi, Nadiya,Gilandoust, Maryam,Bakhit, Neda
-
experimental part
p. 703 - 708
(2012/07/14)
-
- H5IO6/KI: A new combination reagent for iodination of aromatic amines, and trimethylsilylation of alcohols and phenols through in situ generation of iodine under mild conditions
-
A simple method for the in situ generation of iodine using H 5IO6/KI has been developed, and its application in silylation of OH group and iodination of aromatic amines is described.
- Zolfigol, Mohammad Ali,Khazaei, Ardeshir,Kolvari, Eskandar,Koukabi, Nadiya,Soltani, Hamid,Behjunia, Maryam
-
experimental part
p. 587 - 594
(2010/06/14)
-
- Green and efficient procedure for the trimethylsilylation of hydroxy groups and their regeneration using sulfamic acid as recyclable catalyst
-
Structurally diverse alcohols and phenols were efficiently transformed into their corresponding trimethylsilyl ethers with hexamethyldisilazane (HMDS) in the presence of catalytic amounts of sulfamic acid (SA) at room temperature under both acetonitrile and solvent-free conditions. Deprotection of these trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. Copyright Taylor & Francis Group, LLC.
- Rostami, Amin,Ahmad-Jangi, Firoz,Zarebin, Mohammad Rezgar,Akradi, Jamal
-
experimental part
p. 1500 - 1507
(2010/07/15)
-
- Boric acid as cost-effective and recyclable catalyst for trimethylsilyl protection and deprotection of alcohols and phenols
-
Boric acid has been used as a green, selective and recyclable catalyst for trimethysilylation of alcohols and phenols using hexamethyldisilazane in acetonitrile. Deprotection of trimethylsilyl ethers to their parent alcohols and phenols was also achieved using this catalyst in water at room temperature. The salient features of this methodology are cheap processing, mild acidity conditions, excellent yields of products and easy availability of the catalyst.
- Rostami, Amin,Akradi, Jamal,Ahmad-Jangi, Firoz
-
experimental part
p. 1587 - 1592
(2010/11/04)
-
- Silylation of alcohols and phenols using hexamethyldisilazane catalyzed by N,N'-diiodo-N,N'-1,2-ethanediyl bis(p-toluenesulfonamide) under solvent-free and microwave conditions
-
N,N'-Diiodo-N,N'-1,2-ethanediyl bis(p-toluenesulfonamide) (NIBTS) is an effective catalyst for the silylation of alcohols and phenols using hexamethyldisilazane under solvent-free and microwave conditions. Supplemental materials are available for this art
- Ghorbani-Vaghei, Ramin,Malaekehpoor, Seyedeh Mina
-
experimental part
p. 582 - 587
(2010/06/15)
-
- 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)
-
- Catalyst-free silylation of alcohols and phenols by promoting HMDS in CH3NO2 as solvent
-
An uncatalyzed method for the silylation of alcohols and phenols with HMDS in CH3NO2 at rt is developed. A diverse range of aromatic and aliphatic alcohols as well as phenols undergo the silylation in very short reaction time with ex
- Kadam, Santosh T.,Kim, Sung Soo
-
supporting information; experimental part
p. 94 - 98
(2010/05/18)
-
- 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)
-
- Nafion SAC-13: heterogeneous and reusable catalyst for the activation of HMDS for efficient and selective O-silylation reactions under solvent-free condition
-
Nafion SAC-13 effectively activates hexamethyldisilazane (HMDS) for the efficient and selective silylation of alcohols. Primary, secondary, and tertiary alcohols and phenols are efficiently converted to their corresponding silylethers in short reaction ti
- Rajagopal, Gurusamy,Lee, Hanbin,Kim, Sung Soo
-
experimental part
p. 4735 - 4741
(2009/10/09)
-
- Mild and efficient silylation of alcohols and phenols with HMDS using Bi(OTf)3 under solvent-free condition
-
A very efficient and mild silylation of alcohols and phenols with hexamethyldisilazane (HMDS) at rt is developed using Bi(OTf)3 as the catalyst. Primary, secondary and tertiary alcohols as well as phenols are excellently converted into correspo
- Kadam, Santosh T.,Kim, Sung Soo
-
experimental part
p. 2562 - 2566
(2009/12/24)
-
- Novel and highly effective method for the trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS), catalyzed by I2 generated in situ using Fe(NO3)3 · 9 H 2O/NaI under heterogeneous and neutral conditions
-
Structurally diverse alcohols and phenols were trimethylsilylated in a clean and efficient reaction with hexamethyldisilazane (HMDS) based on the use of I2 generated in situ from Fe(NO3)3 · 9 H2O/NaI. The reaction occurs very rapid in good-to-high yield in CH2Cl2 at room temperature, and the use of toxic and corrosive molecular I2 is avoided.
- Khazaei, Ardeshir,Rahmati, Sadegh,Rostami, Amin
-
experimental part
p. 1434 - 1438
(2009/10/16)
-
- Trimethylsilylation of alcohols and phenols, and direct acetylation of silyl ethers catalyzed by Fe(ClO4)3.6H2O
-
In this article, a mild and efficient protocol for the trimethylsilylation of various aliphatic and benzylic alcohols and phenols with trimethylsilyl chloride using a catalytic amount of ferric perchlorate at room temperature and relatively short reaction times in good to excellent yields is reported. Direct acetylation of trimethylsilyl ethers catalyzed with Fe(ClO4)3.6H2O(0.02 mmol)/Fe(ClO4)3SiO2(0.2 g) using acetic anhydride at ambient temperature is also reported.
- Oskooie, Hossein A.,Heravi, Majid M.,Tehrani, Maryam H.,Behbahani, Farahnaz K.,Heravi, Omid M.
-
experimental part
p. 1729 - 1737
(2010/01/17)
-
- Novel and highly efficient protection of aliphatic alcohols and phenols with hexamethyldisilazane in the presence of La(NO3) 3·6H2O
-
Aliphatic alcohols and phenols are protected with hexamethyldisilazane in the presence of lanthanum nitrate hexahydrate (La(NO3) 3·6H2O) in excellent yields at room temperature. Taylor & Francis Group, LLC.
- Akhlaghinia, Batool
-
experimental part
p. 2530 - 2535
(2010/03/31)
-
- Diaryl ether synthesis in supercritical carbon dioxide in batch and continuous flow modes
-
A high yielding, batch mode synthesis of diaryl ethers and sulfides by an SNAr fluoride-mediated process in scCO2 has been developed; the use of a polymer-supported imidazolium fluoride reagent in batch mode led to the development of
- Lee, Jin-Kyun,Fuchter, Matthew J.,Williamson, Rachel M.,Leeke, Gary A.,Bush, Edward J.,McConvey, Ian F.,Saubern, Simon,Ryan, John H.,Holmes, Andrew B.
-
supporting information; experimental part
p. 4780 - 4782
(2009/03/12)
-
- 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 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)
-
- A new and efficient method for the protection of alcohols and phenols by using hexamethyldisilazane in the presence of anhydrous ferric chloride under mild reaction conditions
-
Alcohols and phenols are protected with hexamethyldisilazane in the presence of anhydrous ferric chloride in good to excellent yields in acetonitrile. This method is highly selective for the conversion of primary alcohols in the presence of secondary and
- Akhlaghinia, Batool
-
p. 687 - 694
(2008/02/04)
-
- Efficient trimethylsilylation of alcohols and phenols with HMDS in the presence of a catalytic amount of 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as a safe and cheap industrial chemical
-
1,3-Dibromo-5,5-dimethylhydantoin (DBDMH) is found to be an effective catalyst for trimethylsilylation various alcohols and phenols with hexamethyldisilazane (HMDS) in dichloromethane at room temperature.
- Khazaei, Ardeshir,Rostami, Amin,Mahboubifar, Marjan
-
p. 483 - 487
(2008/02/11)
-
- N-Bromosuccinimide (NBS) - Selective and effective catalyst for trimethylsilylation of alcohols and phenols using hexamethyldisilazane and their regeneration under mild and neutral reaction conditions
-
Structurally diverse alcohols and phenols were trimethylsilylated in a clean and efficient reaction with hexamethyldisilazane (HMDS) based on the use of a catalytic amount of N-bromosuccinimide under both dichloromethane and solvent-free conditions at roo
- Khazaei, Ardeshir,Rostami, Amin,Raiatzadeh, Ayeh,Mahboubifar, Marjan
-
p. 336 - 340
(2008/03/14)
-
- N,N′-dibromo-N,N′-1,2-ethanediylbis (benzene sulfonamide) as a novel N-bromo reagent-catalyzed trimethylsilylation of alcohols and phenol with hexamethyldisilazane in both solution and solvent-free conditions
-
Preparation and catalytic application of N,N′-dibromo-N,N′ -1,2-ethanediylbis (benzene sulfonamide) for the trimethylsilylation of several of alcohols and phenols with hexamethyldisilazane in good to excellent yields under both solution and solvent-free c
- Khazaei, Ardeshir,Rostami, Amin,Rahmati, Sadegh,Mahboubifar, Marjan
-
p. 537 - 544
(2007/10/03)
-
- Trimethylsilylation of alcohols and phenols using KBr as an efficient and reusable catalyst
-
KBr acts as an efficient and reusable catalyst for the selective and efficient trimethylsilylation of benzylic, primary and secondary aliphatic alcohols and phenols with hexamethyldisilazane. All reactions were performed at room temperature under mild and
- Shirini, Farhad,Mollarazi, Esmail
-
p. 1109 - 1115
(2007/10/03)
-
- An efficient method for the protection of alcohols and phenols by using hexamethyldisilazane in the presence of cupric sulfate pentahydrate under neutral reaction conditions
-
Alcohols and phenols are protected with hexamethyldisilazane in the presence of cupric sulfate pentahydrate in good to excellent yields in acetonitrile. The method is highly selective for the conversion of primary alcohols in the presence of secondary and tertiary alcohols as well as phenols. Georg Thieme Verlag Stuttgart.
- Akhlaghinia, Batool,Tavakoli, Sedigheh
-
p. 1775 - 1778
(2007/10/03)
-
- 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
-
p. 3105 - 3114
(2007/10/03)
-
- Electrophilic Hydroxylation with Bis(trimethylsilyl)peroxide. A Synthon for the Hydroxyl Cation
-
The regiospecific introduction of an hydroxy group in aromatic and aliphatic compounds can be performed in good yields by electrophilic hydroxylation of their organometallic derivatives with bis(trimethylsilyl)peroxide.
- Taddei, Maurizio,Ricci, Alfredo
-
p. 633 - 635
(2007/10/02)
-
- TRIMETHYLSILYL TRICHLOROACETATE: A NEW REAGENT FOR SALT-FREE SILYLATIONS
-
Trimethylsylil trichloroacetate (1) is a convenient reagent for the silylation of phenols, carboxylic acids, mercaptans, amides, acetylenes, and β-keto esters, while the reaction of 1 with aldehydes and ketones affords silylated trichloromethyl carbinols (5).
- Renga, James M.,Pen-Chung, Wang
-
p. 1175 - 1178
(2007/10/02)
-
- Fragmentation of Trimethylsilyl Derivatives of 2-Alkoxyphenols: a Further Violation of the 'Even-electron Rule'
-
The mass spectra of trimethylsilyl (TMS) ethers of 2-methoxyphenols show abundant +* ions originating from consecutive loss of two methyl radicals.This is illustrated by comparison of the accurate mass-measured and linked-scan spectra of the TMS derivatives of 2-methoxyphenol (guaiacol), 4-hydroxy-3-methoxybenzaldehyde (vanillin) and 3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid methyl ester (ferulic acid methyl ester) with those of the TMS derivatives of phenol, 4-hydroxybenzaldehyde, 3-(4-hydroxyphenyl)-2-propenoic acid methyl ester (p-coumaric acid methyl ester), 3-methoxyphenol and 4-methoxyphenol.This distinctive ortho effect is valuable in the identification of isomeric phenolic compounds.In the spectra of the TMS derivatives of 2-ethoxyphenol and 2-propoxyphenol the sequential loss of two radicals is less pronounced, because elimination of the side-chain and methyl group with rearrengement and hydrogen migration is competitive.
- Krauss, Dietlinde,Mainx, Hans Georg,Tauscher, Bernhard,Bischof, Peter
-
p. 614 - 618
(2007/10/02)
-
- Oxidation of Hydroquinone Silyl Esters to Quinones
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The electrochemical oxidation of trialkylsiloxybenzene derivatives was investigated using platinum and graphite anodes in either acetonitrile or methylene chloride solvent.Preparative oxidation of the bis(trimethylsilyl) ethers of hydroquinone, chlorohydroquinone, 2,5-di-tert-butylhydroquinone, and 9,10-dihydroxyanthracene gave the corresponding quinones in 80-90percent yield.Oxidation of 1,4-bis(trimethylsiloxy)-2-methoxybenzene in acetonitrile gave 3,6-dihydroxy-2,7-dimethoxydibenzofuran in 65percent yield.Oxidation of 1-methoxy-4-(trimethylsiloxy)benzene in methanolic acetonitrile produced 1,1-dimethoxy-2,5-cyclohexadien-4-one in 99percent yield.The cyclic voltammograms of the trimethylsilyl, triethylsilyl, and tert-butyldimethylsilyl ethers of 2,5-di-tert-butylhydroquinone were recorded using acetonitrile and methylene chloride solvents at 25 and -60 deg C.These compounds were found to react by initial one-electron oxidation to generate a cation radical which decomposes by silicon-oxygen bond cleavage to eventually form quinone.The relative rates for decomposition of the trimethylsilyl, triethylsilyl, and tert-butyldimethylsilyl ether cation radicals at -60 deg C were 10:5:1. tert-Butyldimethylsilyl chloride and tert-butyldimethylsilyl triflate were found to be stable toward cathodic reduction in dry methylene chloride and acetonitrile at potentials as negative as -2.1 vs.Ag/0.1 M AgNO3.Cyclic voltammetry indicated that reduction of 2,5-di-tert-butylbenzoquinone, anthraquinone, and naphthoquinone in the presence of tert-butyldimethylsilyl chloride resulted in reductive silylation.
- Stewart, Ray F.,Miller, Larry L.
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p. 4999 - 5004
(2007/10/02)
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