- Nickel-mediated hydrogenolysis of C-O bonds of aryl ethers: What is the source of the hydrogen?
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Mechanistic studies of the hydrogenolysis of aryl ethers by nickel were undertaken with (diphosphine)aryl methyl ethers. A Ni(0) complex containing Ni-arene interactions adjacent to the aryl-O bond was isolated. Heating led to aryl-O bond activation and generation of a nickel aryl methoxide complex. Formal β-H elimination from this species produced a nickel aryl hydride which can undergo reductive elimination in the presence of formaldehyde to generate a carbon monoxide adduct of Ni(0). The reported complexes map out a plausible mechanism of aryl ether hydrogenolysis catalyzed by nickel. Investigations of a previously reported catalytic system using isotopically labeled substrates are consistent with the mechanism proposed in the stoichiometric system, involving β-H elimination from a nickel alkoxide rather than cleavage of the Ni-O bond by H2.
- Kelley, Paul,Lin, Sibo,Edouard, Guy,Day, Michael W.,Agapie, Theodor
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Read Online
- Use of Silylated Formiates as Hydrosilane Equivalents
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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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- Silylation of O-H bonds by catalytic dehydrogenative and decarboxylative coupling of alcohols with silyl formates
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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
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supporting information
p. 11697 - 11700
(2017/11/03)
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- P2O5/SiO2 as an efficient and mild catalyst for trimethylsilylation of alcohols using hexamethyldisilazane
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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
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p. 1435 - 1439
(2013/02/22)
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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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- 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
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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
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experimental part
p. 582 - 587
(2010/06/15)
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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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- 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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- A novel efficient method for the silylation of alcohols using hexamethyldisilazane in an ionic liquid
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Benzylic and primary alcohols were protected by hexamethyldisilazane in good to excellent yields at r.t. in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) ionic liquid. In addition, the ionic liquid was recovered quantitatively and reused efficiently in the next reactions. The protocol was successfully applied to the protection of phenols. Copyright Taylor & Francis Group, LLC.
- Mojtahedi, Mohammad M.,Abbasi, Hassan,Abaee, M. Saeed
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p. 1541 - 1544
(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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- 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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- Liquid-Crystalline D-Glucose Dialkyl Acetals and Dodecyl D-Glucofuranosides
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Two new systems of liquid crystalline glucose derivatives 5a-d, 6a, b are prepared, studied and compared with reference compounds.The α- and β-D-dodecyl glucofuranosides 6a, b show smectic A phases.The clearing points of the furanosides are of the same magnitude as those of the pyranosides.The alkyl glucose acetals 5a-d show columnar discotic phases.The clearing points are about 30 deg C lower than those of the corresponding thioacetals. - Key Words: Acetals / Amphiphiles / Carbohydrates / Glucosides / Liquid crystals
- Tietze, Lutz F.,Boege, Kai,Vill, Volkmar
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p. 1065 - 1068
(2007/10/02)
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- Protection of Hydroxy Groups by Silylation: Use in Peptide Synthesis and as Lipophilicity Modifiers for Peptides
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A survey of a series of organosilyl derivatives of serine and tyrosine has shown that they have a satisfactory stability profile for use in peptide synthesis.Only when alkaline conditions were used did side-reactions appear.A range of stability profiles have been determined from a study of organosilyl derivatised dipetides under different conditions, giving t1/2 values for hydrolysis ranging from 41 to 465 min in acid conditions, yet giving long-term stability at pH-values near to neutrality.
- Davies, John S.,Higginbotham, Clement L.,Tremeer, E. John,Brown, Charles,Treadgold, Richard C.
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p. 3043 - 3048
(2007/10/02)
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- Organometallic substrates of enzymes: lipase catalysed transesterifications in organic solvents via O-stannyl ethers
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Lipases from pig pancreas and from Chromobacterium viscosum (but not from Candida cylindracea) catalyze transesterification reactions between ethyl esters of carboxylic acids and tributylstannyl ethers of primary and secondary alcohols.At concentrations 1M or higher in anhydrous hydrocarbons, use of these nucleophilic derivatives of alcohols gives reaction rates ca. three times higher than those for the corresponding alcohols.
- Therisod, Michel
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- Silylation process
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Process for silylating an organic or an organosilicon compound having at least one hydroxyl group bonded to carbon or to silicon, wherein the compound is contacted with both (i) a bis-triorganosilyl(alkylenediamine) and (ii) a triorganohalosilane. The process can be employed for the silylation of intermediates in the production of pharmaceuticals.
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