- A Stepwise Mechanism for Gas-Phase Unimolecular Ion Decompositions. Isotope Effects in the Fragmentation of tert-Butoxide Anion
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Infrared multiple photon (IRMP) photochemical activation of gas-phase ions trapped in an cyclotron resonance (ICR) spectrometer has been used to the mechanism of a gas-phase negative ion unimolecular decomposition.Upon irradiation with a CO2 laser (both high-power pulsed and low-power continous wave (CW)), tert-butoxide anion, trapped in a pulsed ICR spectrometer, decomposes to yield acetone enolate anion and methane.The mechanism of this formal 1,2-elimination reaction was probed by measuring hydrogen isotope effects (both primary and secondary) in the IR laser photolysis of 2-methyl-2-propoxide-1,1,1-d3 (1) and 2-methyl-2-propoxide-1,1,1,3,3,3-d6 (2) anions.Unusually large secondary isotope effects (pulsed laser, 1.9 for 1 and 1.7 for 2; cw laser, 8 for 1) and small primary isotope effects (pulsed laser, 1.6 for 1 and 2; cw laser, 2.0 for 1) were observed.These isotope effects, particularly the large difference in energy dependence of the primary and secondary effects, are consistent only with a stepwise mechanism involving initial bond cleavage to an intermediate ion-molecule complex followed by a hydrogen transfer within the intermediate complex.The observed secondary isotope effects have been modelled by using statistical reaction rate (RRKM) theory.The implications of this study for several previously reported unimolecular ion decompositions are also discussed.
- Tumas, William,Foster, Robert F.,Pellerite, Mark J.,Brauman, John I.
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- Silylated Sulfuric Acid: Preparation of a Tris(trimethylsilyl)oxosulfonium [(Me3Si?O)3SO]+ Salt
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The chemistry of silylated sulfuric acid, O2S(OSiMe3)2 (T2SO4, T=Me3Si; also known as bis(trimethylsilyl) sulfate), has been studied in detail with the aim of synthesizing the formal autosilylation products of silylated sulfuric acid, [T3SO4]+ and [TSO4]?, in analogy to the known protonated species, [H3SO4]+ and [HSO4]?. The synthesis of the [TSO4]? ion only succeeds when a base, such as OPMe3 that forms a weakly coordinating cation upon silylation, is reacted with T2SO4, resulting in the formation of [Me3POT]+[TSO4]?. [T3SO4]+ salts could be isolated starting from T2SO4 in the reaction with [T?H?T]+[B(C6F5)4]? or T+[CHB11Br6H5]? when a weakly coordinating anion is used as counterion. All silylated compounds could be crystallized and structurally characterized.
- Bl?sing, Kevin,Labbow, Rene,Schulz, Axel,Villinger, Alexander
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- Tributyltin grafted onto the surface of 3-aminopropyl functionalized γ-Fe2O3 nanoparticles: A magnetically-recoverable catalyst for trimethylsilylation of alcohols and phenols
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Bonding of a homogenous tributyltin chloride catalyst on the surface of functionalized magnetic nanoparticles provides a new stable, efficient and magnetically recyclable catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazan un
- Nikbakht, Fatemeh,Ghonchepour, Ehsan,Ziyadi, Hakimeh,Heydari, Akbar
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- Organosilicon hypersilylchalcogenolates and related compounds
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Reaction of potassium hypersilylchalcogenolates (Me3Si) 3SiEK (E = S, Se, Te) with organochlorosilanes R 4 - xSiClx (R = Me, Ph; x = 1-4) and methylchlorodisilanes (Si2Me5Cl, 1,2-Si2Me4Cl 2) yields organosilicon hypersilylchalcogenolates [(Me 3Si)3SiE]xSiR4 - x (x = 1-4) and [(Me3Si)3SiE]xSi2Me6 - x (x = 1, 2). A partial substitution product, [(Me3Si) 3SiSe]2SiPhCl (2) has been obtained by reaction of PhSiCl3 with 1.5 equivalents (Me3Si)3SiSeK. Besides characterization by 1H, 13C, 29Si, 77Se and 125Te NMR spectroscopy the compounds [(Me 3Si)3SiTe]2SiPh2 (1), [(Me 3Si)3SiSe]2SiPhCl (2) and [(Me 3Si)3SiSe]2Si2Me4 (3) have also been analyzed by crystal structure analyses. Reaction of potassium hypersilylchalcogenolates (Me3Si)3SiEK (E = S, Se, Te) with organochlorosilanes R4 - xSiClx (R = Me, Ph; x = 1-4) and methylchlorodisilanes (Si2Me5Cl, 1,2-Si 2Me4Cl2) yields organosilicon hypersilylchalcogenolates [(Me3Si)3SiE] xSiR4 - x (x = 1-4) and [(Me3Si) 3SiE]xSi2Me6 - x (x = 1, 2). A partial substitution product, [(Me3Si)3SiSe] 2SiPhCl (2) has been obtained by reaction of PhSiCl3 with 1.5 equivalents (Me3Si)3SiSeK. Besides characterization by 1H, 13C, 29Si, 77Se and 125Te NMR spectroscopy the compounds [(Me3Si) 3SiTe]2SiPh2 (1), [(Me3Si) 3SiSe]2SiPhCl (2) and [(Me3Si) 3SiSe]2Si2Me4(3) have also been analyzed by crystal structure analyses. Starting from (Me3Si) 5Si2K treatment with sulfur gave the highly branched potassium heptasilanylthiolate (Me3Si)5Si2SK. Reactions with methylchlorosilanes Me4 - xSiClx (x = 1, 2, 3) yielded organosilicon heptasilanylthiolates [(Me3Si) 3Si-(Me3Si)2Si-S]xSiMe 3 - x.
- Lange, Heike,Herzog, Uwe,Borrmann, Horst,Walfort, Bernhard
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- Bis(oligosilanyl)chalcogenides [Me3Si)xMe3-xSi]2E, alkalimetal oligosilanylchalcogenolates (Me3Si)xMe3-xSi-EMI and oligosilanylchalcogenols (Me3Si)xMe3-xSi-EH (E = S, Se, Te) syntheses and NMR study
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Bis(oligosilanyl)chalcogenides [(Me3Si)x Me3-x Si]2E, alkalimetal oligosilanylchalcogenolates (Me3Si)x Me3-x Si-EMI and oligosilanylchalcogenols (Me3Si)x Me3-x Si-EH (x=1-3; E=S, Se, Te) were synthesized and characterized by 1H-, 13C-, 29Si-, 77Se- and 125Te-NMR spectroscopy. Trends of NMR parameters (chemical shifts, coupling constants) are discussed.
- Lange, Heike,Herzog, Uwe
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- Chemoselective silylation of alcohols
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Hexamethyldisilazane (HMDS) in pesence of a catalytic amount of Envirocat EPZG silylates different alcohols in high yields with absolute chemoselectivity.
- Bandgar,Wadgaonkar
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Read Online
- Novel protocol for the synthesis of organic ammonium tribromides and investigation of 1,1′-(Ethane-1,2-diyl)dipiperidinium bis(tribromide) in the silylation of alcohols and thiols
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A novel and efficient protocol for the synthesis of organic ammonium tribromides (OATBs) is developed by using inexpensive and eco-friendly periodic acid as an oxidant for the conversion of Br-to Br3-. The method does not use any mineral acid and metal oxidants. The protocol is utilized to synthesize a new bis(tribromide) viz., 1,1′-(ethane-1,2-diyl)dipiperidinium bis(tribromide) (EDPBT). EDPBT is investigated as a catalyst in the silylation of alcohols and thiols by HMDS (hexamethyldisilazane) under solvent-free conditions.
- Dey, Rupa R.,Paul, Bappi,Dhar, Siddhartha S.,Bhattacharjee, Sushmita
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- Copper-Catalyzed Cross-Nucleophile Coupling of β-Allenyl Silanes with Tertiary C-H Bonds: A Radical Approach to Branched 1,3-Dienes
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Described herein is a distinctive approach to branched 1,3-dienes through oxidative coupling of two nucleophilic substrates, β-allenyl silanes, and hydrocarbons appending latent functionality by copper catalysis. Notably, C(sp3)-H dienylation proceeded in a regiospecific manner, even in the presence of competitive C-H bonds that are capable of occurring hydrogen atom transfer process, such as those located at benzylic and other tertiary sites, or adjacent to an oxygen atom. Control experiments support the intermediacy of functionalized alkyl radicals.
- Shan, Qi-Chao,Hu, Lu-Min,Qin, Wei,Hu, Xu-Hong
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supporting information
p. 6041 - 6045
(2021/08/03)
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- Hydrogenolysis of Polysilanes Catalyzed by Low-Valent Nickel Complexes
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The dehydrogenation of organosilanes (RxSiH4?x) under the formation of Si?Si bonds is an intensively investigated process leading to oligo- or polysilanes. The reverse reaction is little studied. To date, the hydrogenolysis of Si?Si bonds requires very harsh conditions and is very unselective, leading to multiple side products. Herein, we describe a new catalytic hydrogenation of oligo- and polysilanes that is highly selective and proceeds under mild conditions. New low-valent nickel hydride complexes are used as catalysts and secondary silanes, RR′SiH2, are obtained as products in high purity.
- Comas-Vives, Aleix,Eiler, Frederik,Grützmacher, Hansj?rg,Pribanic, Bruno,Trincado, Monica,Vogt, Matthias
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supporting information
p. 15603 - 15609
(2020/04/29)
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- The reaction of (tert-Butoxysilyl)methylmagnesium chlorides with some organotin and organosilicon monochlorides
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Interaction between (tert-butoxysilyl)methylmagnesium chlorides of the general formula Me3-n(t-BuO)nSiCH2MgCl, n = 1–3, with some organotin and organosilicon monochlorides has been studied. It has been found that the reaction of the Grignard reagents with trialkyltin chlorides readily proceeds via the methylene carbon with the formation of C-substituted products Me3-n(t-BuO)nSiCH2SnR3, R = Me, n-Bu in high yields. The path of this reaction with Me3SiCl and MePh2SiCl depends on the structure of Grignard compound and chlorosilane electrophilicity. Increasing the number of the tert-butoxy groups in the Grignard reagent has unexpectedly been found to result in the formation of Me3-n(t-BuO)nSiCH2OSiMeR2, R = Me, Ph and decrease of the organosilylmethyl silicon compounds content in the reaction products. The structure of the compounds synthesized has been confirmed by 1H, 13C, 29Si, 117,119Sn NMR spectroscopy and mass spectrometry.
- Bykova, Irina A.,Kisin, Alexander V.,Monin, Evgeny A.,Nosova, Valentina M.,Philippov, Alexander M.,Storozhenko, Pavel A.
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- Fast and efficient method for Silylation of alcohols and phenols with HMDS in the presence of bis-thiourea complexes of cobalt, nickel, copper and zinc chlorides
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Bis-thiourea complexes of cobalt, nickel, copper and zinc chlorides were used efficiently for rapid and efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) in CH3CN. All reactions were carried out at room temperature within immediate-120?min timeframe to afford trimethylsilyl ether derivatives in high to excellent yields. Investigation of the results exhibited that the prepared bis-thiourea metal complexes show the activity as Co(tu)2Cl2> Ni(tu)2Cl2> Cu(tu)2Cl2> Zn(tu)2Cl2 in their silylation reactions.
- Zeynizadeh, Behzad,Sorkhabi, Serve
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p. 127 - 135
(2018/02/06)
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- Reactivity of Cyclic Silenolates Revisited
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The stable exocyclic silenolates 2a-c (2a, R = Mes; 2b, R = o-Tol; 2c, R = 1-Ad) were fully characterized by NMR and UV-vis spectroscopy. According to spectroscopic and structural features, 2a-c are best described as acyl silyl anions (tautomeric structure I) in solution. This behavior is also reflected by the reaction of 2a,c with MeI. Both alkylation reactions take place at the corresponding silicon atom and lead to the formation of the methylated structures 4a,b in nearly quantitative yields. Furthermore, the thermal stability of exocyclic silenolates 2a,c was investigated. In the case of 2a, a thermally induced intramolecular sila-Peterson alkenation was observed at 60 °C. This transformation allowed straightforward access to 2-oxahexasilabicyclo[3.2.1]octan-8-ide 5 as a structurally complex, bicyclic silicon framework. In contrast to that, heating of 2c, as an example of an alkyl-substituted silenolate, led to an unexpected degradation to uncharacterized polymers. However, we were able to isolate the 1-adamantyl-substituted, bicyclic compound 8, which is structurally closely related to 5, by the treatment of 1,4-dipotassium-1,4-bis(trimethylsilyl)cyclohexasilane with 1 equiv of 1-adamantoyl chloride. Again an intramolecular sila-Peterson alkenation is responsible for the formation of 8. The mechanism for this highly selective reaction sequence is outlined and supported by density functional theory (DFT) calculations, which highlight the thermodynamic driving force and the low activation barriers of this multistep transformation.
- Haas, Michael,Leypold, Mario,Schuh, Lukas,Fischer, Roland,Torvisco, Ana,Stueger, Harald
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p. 3765 - 3773
(2017/10/13)
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- Highly efficient protection of alcohols and phenols catalysed by tin porphyrin supported on MIL-101
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The catalytic activity of 5,10,15,20-tetrakis(4-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [SnIV(TNH2PP)(OTf)2], supported on chloromethylated MIL-101, was investigated in the trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) and also their tetrahydropyranylation with 3,4-dihydro-2H-pyran. Excellent yields, mild reaction conditions, short reaction times and reusability of the catalyst without significant decrease in its initial activity are noteworthy advantages of this supported catalyst.
- Zadehahmadi, Farnaz,Tangestaninejad, Shahram,Moghadam, Majid,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Kardanpour, Reihaneh
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p. 209 - 215
(2015/03/30)
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- Selective silylation of alcohols, phenols and oximes using N-chlorosaccharin as an efficient catalyst under mild and solvent-free conditions
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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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- Preparation of nano silica supported sodium hydrogen sulfate: As an efficient catalyst for the trimethyl, triethyl and t-butyldimethyl silylations of aliphatic and aromatic alcohols in solution and under solvent-free conditions
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Nano silica supported sodium hydrogen sulfate has been prepared by mixing NaHSO4 with activated Nano silicagel. We wish to report a new method for the synthesis of trimethyl (TMS), triethyl (TES) and t-butyldimethyl silyl (TBS) ethers from benzylic, allylic, propargylic alcohols, phenols, naphtholes and some of phenolic drugs in the solution and under solvent-free conditions.
- Abri, Abdolreza,Ranjdar, Somayeh
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p. 929 - 934
(2014/10/16)
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- Preparation, characterization and use of 1,3-disulfonic acid imidazolium hydrogen sulfate as an efficient, halogen-free and reusable ionic liquid catalyst for the trimethylsilyl protection of hydroxyl groups and deprotection of the obtained trimethylsilanes
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Novel 1,3-disulfonic acid imidazolium hydrogen sulfate, a halogen-free ionic liquid, is a recyclable and eco-benign catalyst for the trimethylsilyl protection of hydroxyl groups at room temperature under solvent free conditions to afford trimethylsilanes in excellent yields (92-100%) and in very short reaction times (1-5 min). Deprotection of the resulting trimethylsilanes can also be achieved using the same catalyst in methanol. The catalyst was characterized by IR, 1H NMR, 13C NMR and MS studies. All the products were extensively characterized by IR, 1H NMR, MS, and elemental and melting point analyses. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be recovered and reused for several times without loss of activity. The work-up of the reaction consists of a simple separation, followed by concentration of the crude product and purification.
- Shirini, Farhad,Khaligh, Nader Ghaffari,Akbari-Dadamahaleh, Somayeh
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- Highly efficient and selective trimethylsilylation of alcohols and phenols with hexamethyldisilazane catalyzed by polystyrene-bound tin(IV) porphyrin
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In the present work, investigation of the catalytic activity of tetrakis(p-aminophenyl)porphyrinatotin(IV) trifluoromethanesulfonate, [Sn IV(TNH2PP)(OTf)2], supported on chloromethylated polystyrene in the trimethylsilylation of alcohols and phenols with hexamethyldisilazane is reported. The prepared catalyst was characterized by elemental analysis, FT-IR and diffuses reflectance UV-Vis spectroscopic methods. This catalyst was used for selective trimethylsilylation of different alcohols and phenols with HMDS, with short reaction times and high yields. Also the catalyst is of high reusability and stability, in that it was recovered several times without loss of its initial activity.
- Gharaati, Shadab,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj
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experimental part
p. 87 - 95
(2012/05/05)
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- Trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel
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An eco-friendly and mild protocol for trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel using hexamethyldisilazane has been described. Solvent-free and ambient reaction conditions, easy workup, short reaction times, e
- Shaterian, Hamid Reza,Fahimi, Nafiseh,Azizi, Kobra
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experimental part
p. 1604 - 1611
(2011/10/05)
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- Electron-deficient vanadium(IV) tetraphenylporphyrin: A new, highly efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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In the present work, the application of electron-deficient tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V IV(TPP)(OTf)2], in the trimethylsilylation of alcohols and phenols with hexamethydisilazane (HMDS) is reported. This new V(IV) catalyst was used as an efficient catalyst for silylation of not only primary alcohols but also sterically hindered secondary and tertiary alcohols with HMDS. Trimethylsilylation of phenols with HMDS was also performed to afford the desired Trimethylsilyl ethers (TMS) ethers. The chemoselectivity of this method was also investigated. This catalyst can be reused several times without loss of its activity. Copyright
- Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Taghavi, S. Abdolmanaf
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experimental part
p. 687 - 694
(2012/01/06)
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- Capture of NO by a frustrated lewis pair: A new type of persistent N-oxyl radical
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NO your pairs: The intramolecular frustrated Lewis pair (FLP) Mes 2PCH2CH2B(C6F5) 2 captures NO to give the novel N-oxyl radical P/B-FLP-NO. (see scheme). Coordination of NO to the FLP incites H-atom abstraction reactivity with cyclohexene and ethylbenzene to give P/B-FLP-NOH and the O-functionalized P/B-FLP-NOR species. Copyright
- Cardenas, Allan Jay P.,Culotta, Brooks J.,Warren, Timothy H.,Grimme, Stefan,Stute, Annika,Froehlich, Roland,Kehr, Gerald,Erker, Gerhard
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supporting information; scheme or table
p. 7567 - 7571
(2011/10/05)
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- Magnesium hydrogensulfate [Mg(HSO4)2] as an efficient catalyst for the preparation of silyl ethers, dibenzo[a,j]xanthenes, and octahydroxanthene derivatives
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Magnesium hydrogensulfate [Mg(HSO4)2], as a heterogeneous solid acid catalyst, has been used for the mild formation of trimethylsilyl (TMS) ethers from various primary, secondary, and tertiary aliphatic alcohols; aromatic alcohols; a
- Shaterian, Hamid Reza,Doostmohammadi, Razieh,Khorami, Fahimeh,Ghashang, Majid
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experimental part
p. 171 - 180
(2010/04/05)
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- [SnIV(TPP)(BF4)2]: An efficient and reusable catalyst for chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane
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Tin(IV)tetraphenylporphyrinato tetrafluoroborate, [SnIV(TPP)(BF4)2], was used as an efficient catalyst for trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). High-valent [SnIV(TPP)(BF4)2] catalyzes trimethylsilylation of primary, secondary and tertiary alcohols as well as phenols, and the corresponding TMS-ethers were obtained in high yields and short reaction times at room temperature. While, under the same reaction conditions [SnIV(TPP)Cl2] is less efficient to catalyze these reactions. One important feature of this catalyst is its ability in the chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols. The catalyst was reused several times without loss of its catalytic activity.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Gharaati, Shadab
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experimental part
p. 212 - 219
(2010/04/04)
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- Unsuccessful attempts to add alcohols to transient 2-amino-2-siloxy- silenes-leading to a new benign route for base-free alcohol protection
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Thermolytic formation of transient 1,1-bis(trimethylsilyl)-2-dimethylamino- 2-trimethylsiloxysilene (2) from N,N-dimethyl(tris(trimethylsilyl)silyl) methaneamide (1) in presence of a series of alcohols was investigated. The products are, however, not the expected alcohol-silene addition adducts but silylethers formed in nearly quantitative yields. Thermolysis of 1 in the presence of both alcohols (MeOH or iPrOH) and 1,3-dienes (1,3-butadiene or 2,3-dimethyl-1,3-butadiene) gives alkyl-tris(trimethylsilyl)silylethers and the [4+2] cycloadducts between the silene and diene, which confirms the presence of 2 and that it is unreactive towards alcohols. The observed silylethers are substitution adducts where the amide group of the silylamide is replaced by an alkoxy group, and the reaction time is reflected in the steric bulk of the alcohol. Indeed, the formation of silylethers from the reaction of alcohols with silylamide represents a new base-free method for protection of alcohols. The protection reactions using 1 progresses at elevated temperatures, or alternatively, under acid catalysis at ambient temperature, and similar protections can be carried out with N-cyclohexyl(triphenylsilyl)methaneamide and N,N-dimethyl(trimethylsilyl)methaneamide. The latter silylamide can be used under neutral conditions at room temperature. The only by-products are formamides (N,N-dimethylformamide (DMF) or N-cyclohexylformamide), and the reactions can be performed without solvent. In addition to alcohols we also examined the method for protection of diols, thiols and carboxylic acids, and also these reactions proceeded in high yields and with good selectivities. The Royal Society of Chemistry.
- Guliashvili, Tamaz,Tibbelin, Julius,Ryu, Jiyeon,Ottosson, Henrik
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supporting information; experimental part
p. 9379 - 9385
(2011/01/07)
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- Trimethylsilylation of alcohols and phenols, and direct acetylation of silyl ethers catalyzed by Fe(ClO4)3.6H2O
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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.
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experimental part
p. 1729 - 1737
(2010/01/17)
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- A Facile and efficient trimethylsilylation of hydroxyl groups using silica-supported zinc chloride and alumina-supported sodium hydrogensulfate as recyclable heterogeneous catalysts
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Silica-supported zinc chloride (SiO2-ZnCl2) and novel alumina-supported sodium hydrogensulfate (NaHSO4-Al 2O3) as recyclable heterogeneous catalysts have been used for the mild trimethylsilylation of hydroxyl groups under ambient conditions. This procedure also allows for the selective protection of primary and secondary alcohols in the presence of tertiary alcohols.
- Shaterian, Hamid Reza,Khorami, Fahimeh,Doostmohammadi, Razieh,Amirzadeh, Azita,Ghashang, Majid
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experimental part
p. 2227 - 2237
(2010/04/25)
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- Novel and highly efficient protection of aliphatic alcohols and phenols with hexamethyldisilazane in the presence of La(NO3) 3·6H2O
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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
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experimental part
p. 2530 - 2535
(2010/03/31)
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- An efficient method for the silylation of hydroxyl groups with hexamethyldisilazane (HMDS) catalyzed by aluminum tris(dihydrogen phosphate) under solvent-free and ambient conditions
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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 Al(H2PO4)3 as a recyclable heterogeneous catalyst at room temperature in a few minutes with excellent yields under solvent-free conditions is described.
- Shaterian, Hamid Reza,Ghashang, Majid,Riki, Nassrin Tajbakhsh,Asadi, Manijeh
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p. 841 - 845
(2008/12/20)
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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
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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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- Silica-supported ferric chloride (silica-FeCl3): A reusable, easily controllable catalyst for the protection of hydroxyl groups under mild and ambient conditions
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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 mild, simple, efficient, and selective protection of hydroxyl groups using silica-supported sodium hydrogen sulfate as a heterogeneous catalyst
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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
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experimental part
p. 3127 - 3135
(2009/09/25)
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- Alumina perchloric acid (Al2O3-HClO4) as an efficient heterogeneous catalyst for modified preparation of trimethylsilyl ethers
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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
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experimental part
p. 2865 - 2874
(2009/09/25)
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- Alumina sulfuric acid as an efficient and recyclable heterogeneous catalyst for the O-silylation of alcohols, phenols, and oximes
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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
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scheme or table
p. 2584 - 2595
(2009/08/15)
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- Rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by reusable zirconyl triflate, [ZrO(OTf)2]
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In this paper, rapid and efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane in the presence of catalytic amounts of ZrO(OTf)2 is reported. Primary, secondary and tertiary alcohols as well as phenols were efficiently converted to their corresponding TMS ethers in short reaction times at room temperature. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Chahardahcheric, Shahin,Tavakoli, Ziba
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p. 2041 - 2046
(2008/09/19)
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- 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
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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
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p. 687 - 694
(2008/02/04)
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- Efficient and practical protocol for silylation of hydroxyl groups using reusable lithium perchlorate dispread in silica gel under neutral condition
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A very efficient and mild procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols with hexamethyldisilazane on the surface of silica gel dispersed with LiClO4 in room temperature at few minutes in excellent yields under neutral conditions is reported. This procedure also allows the excellent selectivity under LP-SiO2 system for silylation of alcohols in the presence of amine and phenolic hydroxy groups.
- Azizi, Najmedin,Yousefi, Rozbeh,Saidi, Mohammad R.
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p. 817 - 820
(2007/10/03)
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- Silica sulfate, an efficient catalyst for the trimethylsilylation of alcohols
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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
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p. 1823 - 1828
(2007/10/03)
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- Zinc mediated reactions in organic synthesis: Efficient synthesis of silyl ethers under mild conditions
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General and practical method for the syn the sis of silyl ethers in the presence of zinc powder under mild conditions has been described.
- Bandgar, Babasaheb Pandurang,Chavare, Satish Navnath,Pandit, Shivaji Sandu
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p. 125 - 128
(2007/10/03)
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- An efficient method for the protection of alcohols and phenols by using hexamethyldisilazane in the presence of cupric sulfate pentahydrate under neutral reaction conditions
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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
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p. 1775 - 1778
(2007/10/03)
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- Aluminium triflate [Al(OTf)3] as a recyclable catalyst for the conversion of α-hydroxyphosphonates, alcohols and phenols to their corresponding O-silylated products with hexamethyldisilazane (HMDS)
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Al(OTf)3 as a recyclable catalyst conducts the efficient conversion of various types of α-hydroxyphosphonates to their corresponding α-trimethysilyloxyphosphonates with HMDS in the absence of solvent at room temperature. The general applicabili
- Firouzabadi, Habib,Iranpoor, Nasser,Sobhani, Sara,Ghassamipour, Soheila
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p. 595 - 599
(2007/10/03)
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- Silyl methallylsulfinates: Efficient and powerful agents for the chemoselective silylation of alcohols, polyols, phenols and carboxylic acids
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Alcohols, phenols and carboxylic acids are silylated with very good yields in the presence of silyl methallylsulfinates under non-basic conditions and with the formation of volatile co-products. The Royal Society of Chemistry 2005.
- Huang, Xiaogen,Craita, Cotinica,Awad, Loay,Vogel, Pierre
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p. 1297 - 1299
(2008/03/28)
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- A Convenient Method for Protection and Deprotection of Alcohols and Phenols as Alkylsilyl Ethers Catalyzed by Iodine under Microwave Irradiation
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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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- Tungstophosphoric acid (H3PW12O40) as a heterogeneous inorganic catalyst. Activation of hexamethyldisilazane (HMDS) by tungstophosphoric acid for efficient and selective solvent-free O-silylation reactions
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The role of tungstophosphoric acid (H3PW12O40) as heterogeneous organic catalysts was discussed. Activation of hexamethyldisilazane by tungstophosphoric acid for efficient and selective solvent-free O-silylation reactions
- Firouzabadi, Habib,Iranpoor, Nasser,Amani, Kamal,Nowrouzi, Farhad
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p. 2601 - 2604
(2007/10/03)
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- Phosphomolybdic acid, an efficient catalyst for the trimethylsilylation of alcohols
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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)
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- Chemoselective protection of hydroxyl groups and deprotection of silyl ethers
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Trimethylsilylation of alcohols and phenols is carried out using hexamethyldisilazane and LiClO4 under microwave irradiation and neutral conditions. The deprotection of silyl ethers is carried out similarly using natural kaolinitic clay and a few drops of water.
- Bandgar,Kasture
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p. 1101 - 1104
(2007/10/03)
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- A new and easy route to polysilanylpotassium compounds
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A method is presented for the synthesis of tertiary, secondary, and primary polysilylpotassium compounds. Reaction of potassium tert-butoxide, in either DME or THF, with a suitable precursor molecule, proceeds by cleavage of a trimethylsilyl - polysilanyl bond, and formation of trimethylsilyl tert-butyl ether and a polysilanylpotassium compound. This route allows easy and flexible access to a number of novel polysilanylpotassium compounds, avoiding the hitherto common use of poisonous mercury compounds.
- Marschner, Christoph
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p. 221 - 226
(2007/10/03)
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- Silicon-29 NMR spectra of trimethylsilylated alcohols
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29Si NMR spectra of trimethylsilyl (TMS) derivatives of 26 simple alcohols were measured under standardized conditions (i.e., in sufficiently diluted deuteriochloroform solutions). Due to association with the solvent the chemical shifts are in almost all cases larger than those reported earlier for different solutions. This observation is in agreement with the proposed mechanism of steric effects as being due to sterically controlled association with the solvent. The use of chloroform as a solvent enhances steric effects hut at the same time it can reduce small differences due to polar effects in closely related compounds. In the studied class of compounds the gross dependence of the chemical shift on polar effects is not substantially affected by the change of the solvent.
- Kvicalova, Magdalena,Cermak, Jan,Blechta, Vratislav,Schraml, Jan
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p. 816 - 820
(2007/10/03)
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- Yttrium-based Strong Lewis Acid Catalyst for Silylation of Alcohols with 1,1,1,3,3,3-Hexamethyldisilazane
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A variety of hydroxy compounds react with hexamethyldisilazane in the presence of a yttrium-based Lewis acid catalyst to afford the corresponding trimethylsilyl ethers in good to excellent yields.
- Kumar, Pradeep,Pais, Godwin C. G.,Keshavaraja
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p. 376 - 377
(2007/10/03)
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- Natural kaolinitic clay : A mild and efficient catalyst for the tetrahydropyranylation and trimethylsilylation of alcohols
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Natural kaolinitic clay possessing transition metals such as Fe, Ti in its lattice has been found to catalyze efficiently the protection of a variety of alcohols with 2,3-dihydro-4H-pyran (DHP) and hexamethyldisilazane (HMDS) at ambient conditions.
- Upadhya,Daniel,Sudalai,Ravindranathan,Sabu
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p. 4539 - 4544
(2007/10/03)
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- Photochemical protodesilylation of 2-R3Si-1,3-dimethoxybenzenes. Direct observation of β-silyl-substituted cyclohexadienyl cations
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Irradiation (254 nm) of the title compounds 5 (R3Si = Me3Si, Ph2MeSi, and 4-XC6H4Me2Si with X = 4-MeO, 4-Me, H, 4-F, and 4-Cl) in 1,1,1,3,3,3-hexafluoroisopropyl alcohol (HFIP) results in q
- Lew, Calvin S. Q.,McClelland, Robert A.
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p. 11516 - 11520
(2007/10/02)
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- Carbanion mechanisms XVIII. Generation of silyl anions by nucleophilic cleavage of disilanes
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Organosilyl potassium compounds are conveniently generated by cleavage of hexaorganodisilanes with potassium t-butoxide in common solvents other than HMPA (i.e. in THF or DME).Nucleophilic attack on unsymmetrical disilanes results in formation of the more
- Buncel, Erwin,Venkatachalam, T. Krishnan,Edlund, U.
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