- Highly conductive trimethylsilyl oligo(ethylene oxide) electrolytes for energy storage applications
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Monomethyl ethers of oligoethylene glycols with different chain lengths were converted to trimethylsilyl derivatives by reacting with trimethylchlorosilane in the presence of triethylamine, or by directly refluxing with excess trimethylchlorosilane or hex
- Zhang, Lingzhi,Zhang, Zhengcheng,Harring, Scott,Straughan, Megan,Butorac, Rachel,Chen, Zonghai,Lyons, Leslie,Amine, Khalil,West, Robert
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- Co2(CO)8-catalyzed reactions of acetals or lactones with hydrosilanes and carbon monoxide. A new access to the preparation of 1,2-diol derivatives through siloxymethylation
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The Co2(CO)8-catalyzed reaction of acetals with hydrosilanes and CO under mild reaction conditions (an ambient temperature under an ambient CO pressure), leading to the production of vicinal diols is reported. A siloxymethyl group can be introduced via the cleavage of one of two alkoxy groups in the acetal. The effects of the types of hydrosilanes, acetals, solvents, and reaction temperatures on the yield of siloxymethylation products were examined in detail. The reactivity for hydrosilanes is as follows; HSiMe3 > HSiEtMe2 > HSiEt2Me > HSiEt3. Hemiacetal esters are more reactive than dimethyl acetals. The polarity of the solvent used also has a significant effect on both the course of the reaction as well as the reaction rate. The site-selective siloxymethylation can be achieved in the case of cyclic acetals such as tetrahydrofuran (THF) and tetrahydropyrane (THP) derivatives, depending on the nature of the oxygen substituent attached adjacent to the oxygen atom in the ring. When 2-alkoxy THF or THP derivatives are used as substrates, the siloxymethylation takes place with cleavage of the ring C-O bond. In contrast, the reaction of 2-acetoxy THF or THP derivatives results in siloxymethylation with the cleavage of C-OAc bond. The ring-opening siloxymethylation of lactones was also examined.
- Chatani, Naoto,Fujii, Satoru,Kido, Yoichi,Nakayama, Yasuhide,Kajikawa, Yasuteru,Tokuhisa, Hideo,Fukumoto, Yoshiya,Murai, Shinji
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- Glycosyl Fluorides as Intermediates in BF3·OEt2-Promoted Glycosylation with Trichloroacetimidates
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Glycosyl fluorides have been found to be important intermediates in glycosylations with trichloroacetimidate donors and BF3·OEt2 activation (0.2–1 equiv.). Low-temperature NMR spectroscopy experiments revealed that the α-trichloroacetimidate was transformed into the glycosyl fluoride with inversion of stereochemistry, whereas the β anomer was not. A concerted mechanism was suggested for the stereospecific formation of glycosyl fluorides, which is not accounted for in the classic mechanism.
- Nielsen, Michael M.,Stougaard, Bolette A.,Bols, Mikael,Glibstrup, Emil,Pedersen, Christian M.
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supporting information
p. 1281 - 1284
(2017/03/17)
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- 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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- 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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- Reactions of Trialkylsilyl Trifluoromethanesulfonates, IX. - Electrophilic Silylation of Electron-Rich Alkenes
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Ketene O,O-, O,S-, and O,N-acetals 1, 7, and 9 are converted into the C-silylated derivatives 4, 8, and 11, respectively, by reaction with trimethylsilyl triflate (2a)/tertiary amine or sodium hydride.The ambident character of the ketene O,O-acetals 1 in
- Schulz, Dieter,Simchen, Gerhard
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p. 745 - 750
(2007/10/02)
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- Application of the Conformational Transmission Effect for the Assignment of Diastereotopic Proton Resonances
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A new method is presented for the assignment of the NMR resonances of the diastereotopic protons in tetrahydrofurfuryl and pyrrolidinylmethyl groups, based on the conformational transmission effect.This effect describes the conformational changes produced
- Genderen, Marcel H. P. van,Buck, Henk M.
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p. 872 - 878
(2007/10/02)
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