Silane vinyl

Stabilizing the resulting enolate of the Michael Addition product can shift the equilibrium as in the case of the vinyl silane shown below... 

Organofunctional silanes are used to promote polymer-to-filler bonding with clay or siHca fillers. Vinyl silanes are used in peroxide-cured wire insulation to promote stronger bonding with calcined clay fillers. Mercapto silanes are used to treat kaolin clay in sulfur-cured compounds. 

Dianion formation from 2-methyl-2-propen-l-ol seems to be highly dependent on reaction conditions. Silylation of the dianion generated using a previously reported method was unsuccessful in our hands. The procedure described here for the metalation of the allylic alcohol is a modification of the one reported for formation of the dianion of 3-methyl-3-buten-l-ol The critical variant appears to be the polarity of the reaction medium. In solvents such as ether and hexane, substantial amounts (15-50%) of the vinyl-silane 3 are observed. Very poor yields of the desired product were obtained in dirnethoxyethane and hexamethylphosphoric triamide, presumably because of the decomposition of these solvents under these conditions. Empirically, the optimal solvent seems to be a mixture of ether and tetrahydrofuran in a ratio (v/v) varying from 1.4 to 2.2 in this case 3 becomes a very minor component. 

Methyl vinyl dichlorosilane (dichloro methyl vinyl silane) [124-70-9] M 141.1, b 43-45.5 /ll-11.5mm, 91 /742mm, 92.5 /743.2mm, 92.5-93 /atm, d 1.0917, n 1.444. Likely impurities are dichloromethylsilane, butadienyl-dichloromethylsilane. Fractionate through a column packed... 

Trimetbyl vinyl silane [754-05-2] M 100.2, b 54.4 /744mm, 55.5 /767mm, d S(25,4) 0.6865, n D 1.3880. If the H NMR spectrum shows impurities then dissolve in Et20, wash with aq NH4CI soln, dry over CaCl2, filter, evaporate and distil at atmospheric pressure in an inert atmosphere. It is used as a copolymer and may polymerise in the presence of free radicals. It is soluble in CH2CI2. [J Org Chem 17 1379 7952.]... 

Vulcanised (cross-linked) polyethylene is being used for cable application where service temperatures up to 90°C are encountered. Typical cross-linking agents for this purpose are peroxides such as dicumyl peroxide. The use of such agents is significantly cheaper than irradiation processes for the cross-linking of the polymer. An alternative process involves the use of vinyl silanes (see Section 10.9). 

Dimethylberyllium Chromium Molybdenum (IV) Trichloro(vinyl)silane... 

With the use of trimethylsilyl-substituted starting materials after Denmark et al., the disadvantageous formation of a mixture of isomers can be avoided. The vinyl silane derivatives react by loss of the TMS group in the last step ... 

Sinnlarly, f-i- -casuralme, a pentahydroxy pyrrolizidine alkaloid, is prepared by a tandem [4-i-3 /[3-i-3 cycloadchdon involving nitroalkene, chiral vinyl ether, and vinyl silane This process creates five of the six stereocenters present in this potent glycosidase inhibitor fScheme 8 35 ... 

In an effort to identify a more stereoselective route to dihydroagarofuran (15), trimethylsilylated alkyne 17 was utilized as a substrate for radical cyclization (Scheme 2). Treatment of 17 with a catalytic amount of AIBN and tri-n-butyltin hydride (1.25 equiv) furnishes a mixture of stereoisomeric vinyl silanes 18 (72% combined yield) along with an uncyclized reduction product (13% yield). The production of stereoisomeric vinyl silanes in this cyclization is inconsequential because both are converted to the same alkene 19 upon protodesiiyiation. Finally, a diastereoselective di-imide reduction of the double bond in 19 furnishes dihydroagaro-... 

The synthesis of PDMS macromonomers with vinyl silane end-groups and their free-radical copolymerization with vinyl acetate, leading to poly(vinyl acetate)-PDMS graft copolymers, was described 346). The copolymers produced were later hydrolyzed to obtain poly(vinyl alcohol)-PDMS graft copolymers. 

Polystyrene-polydimethylsiloxane (PDMS) triblock (or multiblock) copolymers 123) can be made by hydrosilylation involving a vinyl silane terminated polystyrene and a PDMS fitted at both chain ends with Si—H groups. The former species is ob-... 

Radical-mediated silyldesulfonylation of various vinyl and (a-fluoro)vinyl sulfones 21 with (TMSlsSiH (Reaction 25) provide access to vinyl and (a-fluoro)vinyl silanes 22. These reactions presumably occur via a radical addition of (TMSlsSi radical followed by /)-scission with the ejection of PhS02 radical. Hydrogen abstraction from (TMSlsSiH by PhS02 radical completes the cycle of these chain reactions. Such silyldesulfonylation provides a flexible alternative to the hydrosilylation of alkynes with (TMSlsSiH (see below). On oxidative treatment with hydrogen peroxide in basic aqueous solution, compound 22 undergoes Pd-catalyzed cross-couplings with aryl halides. 

Bowen, R. L. (1962). Dental filling material comprising vinyl silane treated fused silica and a binder consisting of a reaction product of bisphenol and glyddyl acrylate. US Patent 3,066,112. 

Rh colloids were isolated during the hydrosilylation of trimethy(vinyl)silane with triethoxysilane using RhCl3 in EtOH as pre-catalyst. The colour changes observed during the catalytic reaction (from yellow, to red and black) are due to the formation of colloids as demonstrated by TEM this fact was in agreement with the catalytic activity behaviour observed [14]. 

This test was successfully applied for the hydrosilylat-ion of trimethyl(vinyl)silane by triethoxysilane catalysed by Rh or Pt colloids. The addition of mercury to catalytic mixture led to catalytic activity loss, consistent with a heterogeneous catalyst [12,14]. 

Other ruthenium-based catalysts are also active. Ruthenium dichloride-cymene complex is stereoselective for formation of the Z-vinyl silanes from terminal alkynes. 

The differential in chelation capacity between BF3 and SnCl4 was used to control the stereochemistry of the cyclization of the vinyl silane 10." With BF3, the reaction proceeds through a nonchelated TS and the stereochemistry at the new bond is trans. With SnCl4, a chelated TS leads to the cis diastereomer. 

A-Acyliminium ions, which are even more reactive toward allylic and alkenyl-silanes, are usually obtained from imides by partial reduction (see Section 2.2.2). The partially reduced A-acylcarbinolamines can then generate acyliminium ions. Such reactions have been employed in intramolecular situations with both allylic and vinyl silanes. 

In Entry 5, the carbanion-stabilizing ability of the sulfonyl group enables lithiation and is then reductively removed after alkylation. The reagent in Entry 6 is prepared by dilithiation of allyl hydrosulfide using n-bulyl lithium. After nucleophilic addition and S-alkylation, a masked aldehyde is present in the form of a vinyl thioether. Entry 7 uses the epoxidation of a vinyl silane to form a 7-hydroxy aldehyde masked as a cyclic acetal. Entries 8 and 9 use nucleophilic cuprate reagents to introduce alkyl groups containing aldehydes masked as acetals. 

The coupled fragments were then converted to a vinyl iodide. The key steps were a Z-selective Lindlar reduction and iodinolysis of the vinyl silane, which was done using NIS in acetonitrile (sequence F-l to F-ll). 

Chemical surface modifications The first surface modification for the purpose of eliminating EOF and protein adsorption was recommended by Hjerten.28 The attachment of vinyl silanes allowed the polymerization of a variety of molecules to the surface. Most of the chemical modifications used for preparing capillaries for electrophoresis originated from the experience acquired over the years preparing GC and LC stationary phases. Chemical modification should conform to certain requirements, including the prevention of adsorption, the provision of stable and constant EOF over a wide pH range, chemical stability, ease of preparation, and reproduciblity of preparation. The effects of silanization of the inner surface of capillaries on electrophoretic separations have been extensively studied.26-29... 

Clive and coworkers have developed a new domino radical cyclization, by making use of a silicon radical as an intermediate to prepare silicon-containing bicyclic or polycyclic compounds such as 3-271 and 3-272 (Scheme 3.69) [109], After formation of the first radical 3-267 from 3-266, a 5-exo-dig cyclization takes place followed by an intramolecular 1,5-transfer of hydrogen from silicon to carbon, providing a silicon-centered radical 3-269 via 3-268. Once formed, this has the option to undergo another cyclization to afford the radical 3-270, which can yield a stable product either by a reductive interception with the present organotin hydride species to obtain compounds of type 3-271. On the other hand, when the terminal alkyne carries a trimethylstannyl group, expulsion of a trimethylstannyl radical takes place to afford vinyl silanes such as 3-272. 

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