- Salt-free preparation of trimethylsilyl ethers by B(C6F 5)3-catalyzed transfer silylation by using a Me 3SiH surrogate
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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
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supporting information
p. 2077 - 2083
(2014/04/17)
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- Process for the preparation of Drospirenone
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A process for the preparation of Drospirenone (I) according to the following scheme wherein the substituent R is defined in the description. The process improves the product yield and purity by reducing the formation of undesired side-products and is particularly convenient for industrial-scale manufacturing.
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Page/Page column 11-12
(2009/02/10)
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- Facile method for trimethylsilylation of alcohols using hexamethyldisilazane and ammonium thiocyanate under neutral conditions
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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.
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p. 1363 - 1370
(2008/02/01)
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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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- Process of preparing trimethylsilyloxy functionalized alkyllithium compounds
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A process for producing compounds of the formula (CH3)3 SiORLi where in R is selected from alkyl groups containing 2 to 10 carbon atoms and aryl groups containing 6 to 10 carbon atoms by reacting, in an inert atmosphere, in a hydrocarbon solvent, a haloalcohol of the formula HORX wherein R is selected from alkyl groups containing 2 to 10 carbon atoms and aryl groups containing 6 to 10 carbon atoms and X is selected from chlorine or bromine, is reacted with hexamethyldisilazane at a temperature between 20° C. and the reflux temmperature of the solvent after which the resulting product, a trimethylsilyloxyalkylhalide compound, is reacted at a temperature between 50° and 160° C., with powdered lithium metal to produce the (CH3)3 SiORLi compound.
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- MECHANISTIC STUDIES OF THE REACTION OF OXETANES WITH METHYLTHIOTRIMETHYLSILANE
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The zinc chloride-catalyzed reaction of oxetane with methylthiotrimethylsilane yields (3-chloropropoxy)trimethylsilane (minor) and (3-methylthiopropoxy)trimethylsilane (major).Similar results have been obtained with 2-methyloxetane, 3,3-dimethyloxetane and 2,2-dimethyloxetane.These results have been interpreted in terms of competing SN1 and SN2 processes.
- Firgo, Heinrich A.,Weber, William P.
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p. 201 - 210
(2007/10/02)
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- CARBANIONEN-UMLAGERUNGEN DURCH INTRAMOLEKULARE 1,ω-PROTONVERSCHIEBUNG. II. ZUR REAKTIONSWEISE VON 3-, 4- UND 5-LITHIOALKYL-TRIMETHYLSILANEN
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ω-Lithioalkyltrimethylsilanes, prepared from ω-bromoalkyltrimethylsilanes and lithium metal, are fairly stable in diethyl ether as solvent.Upon addition of tetrahydrofuran, however, rearrangements take place, the modes of which are strongly dependent on the number of methylene groups between the lithium and the silicon atoms.With 3-lithiopropyltrimethylsilane an intramolecular 1,5-proton shift with the formation of lithiomethyldimethylpropylsilane is observed.With 4-lithiobutyl-trimethylsilane on the other hand, ring closure to 1,1-dimethylsilacyclopentane takesplace, whereby methyllithium is formed by intramolecular nucleophilic attack on silicon. 5-Lithiopentyltrimethylsilane finally shows ring closure as well as 1,7-proton shift, the ratio depending on the polarity of the solvent.
- Maercker, Adalbert,Eckers, Mechthild,Passlack, Michael
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p. 193 - 205
(2007/10/02)
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