- Synthesis and properties of functionalized alkylalkoxysilanes
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A method of chloroalkylalkoxysilanes synthesis scalable to pilot production has been proposed. Morpholinotrialkoxysilanes have been prepared and studied as vulcanizing agents for low-molecular silicone rubbers. The reaction of N-morpholinomethyltrialkoxysilanes with triethanolamine has afforded N-[(silatranyl)-methyl]morpholine; it has been studied by X-ray analysis.
- Lebedev,Minas’yan,Abramkin,Sheludyakov,Kuzmina,Lebedeva,Surikov,Rybakov
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p. 1859 - 1863
(2016/10/04)
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- Tridentate Lewis Acids Based on 1,3,5-Trisilacyclohexane Backbones and an Example of Their Host-Guest Chemistry
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Directed tridentate Lewis acids based on the 1,3,5-trisilacyclohexane skeleton with three ethynyl groups [CH2Si(Me)(C2H)]3 were synthesised and functionalised by hydroboration with HB(C6F5)2, yielding the ethenylborane {CH2Si(Me)[C2H2B(C6F5)2]}3, and by metalation with gallium and indium organyls affording {CH2Si(Me)[C2M(R)2]}3 (M=Ga, In, R=Me, Et). In the synthesis of the backbone the influence of substituents (MeO, EtO and iPrO groups at Si) on the orientation of the methyl group was studied with the aim to increase the abundance of the all-cis isomer. New compounds were identified by elemental analyses, multi-nuclear NMR spectroscopy and in some cases by IR spectroscopy. Crystal structures were obtained for cis-trans-[CH2Si(Me)(Cl)]3, all-cis-[CH2Si(Me)(H)]3, all-cis-[CH2Si(Me)(C2H)]3, cis-trans-[CH2Si(Me)(C2H)]3 and all-cis-[CH2Si(Me)(C2SiMe3)]3. A gas-phase electron diffraction experiment for all-cis-[CH2Si(Me)(C2H)]3 provides information on the relative stabilities of the all-equatorial and all-axial form; the first is preferred in both solid and gas phase. The gallium-based Lewis acid {CH2Si(Me)[C2Ga(Et)2]}3 was reacted with a tridentate Lewis base (1,3,5-trimethyl-1,3,5-triazacyclohexane) in an NMR titration experiment. The generated host-guest complexes involved in the equilibria during this reaction were identified by DOSY NMR spectroscopy by comparing measured diffusion coefficients with those of the suitable reference compounds of same size and shape.
- Weisheim, Eugen,Reuter, Christian G.,Heinrichs, Peter,Vishnevskiy, Yury V.,Mix, Andreas,Neumann, Beate,Stammler, Hans-Georg,Mitzel, Norbert W.
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p. 12436 - 12448
(2015/08/25)
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- PREPARATION ET ESSAIS DE DEDOUBLEMENT ENZYMATIQUE D'ACETOXYMETHYL-ET HYDROXYMETHYLSILANES CHIRAUX
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Various chirals acetoxymethyl- and hydroxymethylsilanes were synthesized from commercially available chlorosilanes.Several enzymatic-catalyzed hydrolyses or transesterifications have been attempted on these products.Key words: Esterases; lipases; silicium
- Aouf, N. E.,Djerourou, A. H.,Blanco, L.
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p. 207 - 216
(2007/10/02)
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- Chiral Acylsilanes in Organic Synthesis. Diastereoselective 1,2 Additions to Racemic Alkoxymethyl-Substituted Acylsilanes
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The synthesis of the three alkoxymethyl-sustituted acylsilanes 1-3 is described (Schemes 1 and 2).Their reactions with NaBH4 as well as PhLi gave the corresponding alcohols with moderate to good diastereoisomeric induction (up to 78percent de; see Table), depending upon the solvent used (Scheme 3).The results indicate that in Et2O, the reactions with PhLi proceed via 6-membered chelates (see C in Scheme 4) leading to the products with high de's (74 - 78percent).In THF, these chelates are not formed, and as a consequence, the additions take place with reversed and lower stereoselectivities (34 - 50percent de).
- Bienz, Stefan,Chapeaurouge, Alexander
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p. 1477 - 1488
(2007/10/02)
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- Bis(pyrrolidiniomethyl)silicate Acetonitrile Solvate: Synthesis and Crystal and Molecular Structure of a Zwitterionic λ5-Spirosilicate
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The zwitterionic spirocyclic bis-(pyrrolidiniomethyl)silicate (3) was synthesized and the crystal and molecular structure of its acetonitrile solvate 3*CH3CN investigated. 3 was prepared by reaction of trimethoxy(pyrrolidinomethyl)silane (8) or dimethoxy(methyl)(pyrrolidinomethyl)silane (9) with 2,3-dihydroxynaphthalene in acetonitrile.Reaction 9 -> 3 involves a remarkable Si-C cleavage with formation of CH4.The pentacoordinate silicon atom of 3*CH3CN is surrounded by 4 oxygen atoms and 1 carbon atom, the latter being in an equatorial position.The coordination polyhedron can be described as a distorted trigonal bipyramid (the structure is displaced by 20.5percent from the trigonal bipyramid towards the square pyramid).The crystal lattice of 3*CH3CN contains centrosymmetric dimers of 3, built up by intermolecular N-HO hydrogen bonds. Key Words: Spirosilicates, zwitterionic / Bond cleavage, Si-C
- Tacke, Reinhold,Sperlich, Joerg,Strohmann, Carsten,Mattern, Guenter
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p. 1491 - 1496
(2007/10/02)
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