Silanes phenylsilane

Silanes. Phenylsilanes of the type Ph(R)SiH2 are arylated to provide Ph(R)ArSiH on mediation by Yb. ... 

The titanium(IV) chloride catalyzed addition of allylic silanes to (E)-(2-nitroethenyl)benzene affords y,<5-unsaturated nitronates which, on treatment with low valent titanium species [generated in situ from titanium(IV) and zinc], give y,<5-unsaturated nitriles. For example, [(Zs)-2-butenyl]-(dimethyl)phenylsilane underwent reaction with ( )-(2-nitroethenyl)benzene to give 3-methyl-2-phenyl-4-pentenenitrile in 65 % yield as a 3 1 mixture of diastereomers of unassigned configuration22. 

Bis(imino)pyridine iron complex 5 acts as a catalyst not only for hydrogenation (see 2.1) but also for hydrosilylation of multiple bonds [27]. The results are summarized in Table 10. The reaction rate for hydrosilylations is slower than that for the corresponding hydrogenation however, the trend of reaction rates is similar in each reaction. In case of tra s-2-hexene, the terminal addition product hexyl (phenyl)silane was obtained predominantly. This result clearly shows that an isomerization reaction takes place and the subsequent hydrosilylation reaction dehvers the corresponding product. Reaction of 1-hexene with H2SiPh2 also produced the hydrosilylated product in this system (eq. 1 in Scheme 18). However, the reaction rate for H2SiPh2 was slower than that for H3SiPh. In addition, reaction of diphenylacetylene as an atkyne with phenylsilane afforded the monoaddition product due to steric repulsion (eq. 2 in Scheme 18). 

Stoichiometric reaction of 5 with phenylsilane produced the iron(O) bis(silane) c-complex 18, which was confirmed by the single-crystal X-ray analysis as well as SQUID (Superconducting QUantum Interference Device) magnetometry (Scheme 19). Complex 18 as a precatalyst showed high activity for the hydrosilylation of 1-hexene. 

Silane redistribution 6 mg of (3-(methylsilyl)propyl) triphenylphosphonium hexafluorophosphate(V) (0.0121 mmol, 1 equivalent), 93 mg of Karstedt s catalyst (Pt 3.91% 0.000954 mmol, 0.8 equivalent), 6 mg of triphenylphosphine (0.0229 mmol, 1.9 equivalent) were dissolved in 20 mL of freshly distilled fluoroben-zene in a 50 mL Schlenk flask in an inert atmosphere glovebox. The flask was equipped with a septum, removed from the glovebox and installed with PEEK tubing leading to the mass spectrometer. The flask was pressurized with N2 and monitored by ESI-MS. Once a steady signal was obtained, 0.15 g of freshly distilled phenylsilane (1.39 mmol, 115 equivalents) was injected into the reaction flask. The reaction was initiated at room temperature and then was heated to reflux after 20 min to drive it to completion. 

Dienes are less reactive toward transition metals than enynes and diynes, and perhaps for this reason, the development of effective catalyst systems for the cyclization/hydrosilylation of dienes lagged behind development of the corresponding procedures for enynes and diynes. The transition metal-catalyzed cyclization/hydrosilylation of dienes was first demonstrated by Tanaka and co-workers in 1994. Reaction of 1,5-hexadiene with phenyl-silane catalyzed by the highly electrophilic neodymium metallocene complex Cp 2NdCH(SiMe2)3 (1 mol%) in benzene at room temperature for 3 h led to 5- ///76 -cyclization and isolation of (cyclopentylmethyl)phenylsilane in 84% yield (Equation (15)). In comparison, neodymium-catalyzed reaction of 1,6-heptadiene with phenylsilane led to 5- X(9-cyclization to form (2-methylcyclopentylmethyl)phenylsilane in 54% yield as an 85 15 mixture of trans. cis isomers (Equation (16)). 

Diphenylsilane is a convenient alternative [33]. Triphenylsilane and phenylsilane are also quite suitable [34,35]. Even Iriethylsilane can be used if it serves as solvent [36], but it is not as efficient as other silanes because the Si-H bond strength is too great. 

Blends of 10% aminosilane F and 90% hydrophobic silanes, i.e. vinylsilane A, chloropropylsilane B, methylsilane G, and phenylsilane I, gave superior adhesion of three types of polyurethane (RIM, thermoplastic, and one-component rigid) to glass compared with aminosilane F alone. Table 3 shows that the blend with phenylsilane I gave the best adhesion overall to all three polyurethanes after 5 h in boiling water. This improved performance is attributed to the enhanced hydrophobicity of the interphase region which is conferred by the replacement of most of the hydrophilic aminosilane with hydrophobic silane. 

The readily available yttrocene derivative (C5Me5)2YMe(THF) has been shown to be an effective catalyst for the hydrosilylation of internal alkynes [85]. A single stereoisomer, i.e. the product of cis addition of phenylsilane to the alkyne, is formed in the reaction with symmetrically substituted alkynes. Comparable reactions with a variety of unsymmetrically substituted internal alkynes resulted in a regioselective hydrosilylation reaction in which the silane moiety is placed at the sterically less hindered carbon atom of the alkyne. Various functional groups such as halides, amines, protected alcohols, and trisubstituted... 

In addition to ruthenium, Tilley and coworkers also reported that cationic iridium silylenoid complexes were efficient olefin hydrosilation catalysts [reaction (7.6)].56 This silylene complex catalyzes the hydrosilation of unhindered mono- or disubsti-tuted olefins with primary silanes to produce secondary silanes with anti Markovni-kov selectivity. Iridium catalyst 32 exhibited reactivity patterns similar to those of ruthenium 30 only primary silanes were allowed as substrates. In contrast to 30, cationic iridium 32 catalyzed the redistribution of silanes. Exposing phenylsilane to 5 mol% of 32 in the absence of olefin produced diphenylsilane, phenylsilane, and silane. 

E.g., by joint acetylation of methyl- and phenyltrichlorosilanes with phenyltrichlorosilane one can obtain a mixture of triacetoxymethyl- and phenylsilanes, which after methacrylation forms a mixture of silanes with methacrylethyl groups at the silicon atom, apart from the acetate ones. 

Moran et al. 41 attached the Cr(CO)3 moiety to tetrakis(phenylsilane) 32 (prepared by the hydrosilylation of tetraallylsilane with four equivalents of dimethylphenylsilane) by treatment with excess Cr(CO)6 in dibutyl ether—THF at 140 °C affording the air-stable, crystalline tetrakis(chromium carbonyl) dendrimer 33, which was also prepared by reaction of tetraallylsilane with [r76-C6H5Si(Me)2H]Cr(CO)3) (Scheme 8.9). 42a Reaction of the corresponding eight phenyl-terminated analogues afforded the partially metalated silane dendrimer 34 as the major product, even with an excess of Cr(CO)6. 

Bis(hydrazino)silanes are better stabilized with silyl groups bound to the nitrogen atoms. Although Zn-, Cd-, and Hg- connected silylhydrazines were described in 1970,52 silyl-substituted bis(hydrazino)silanes were not known until later. The first bis(hydrazino)silane that was silyl substituted at the terminal nitrogen atom and that showed no tendency to condensation was the terf-butyl-bis[iV,iV -bis(trimethylsilyl)hydrazino]phenylsilane 106, described in 1981.53 A decade later the synthesis of other stable bis(hydrazino)silanes was reported via different preparative methods using (a) mono-, (b) bis-, (c) tris-, and (d) tetrakis(silyl)hydrazines as precursors. 

As discussed in Section III, however, the formation of 11 is not particularly strong evidence for silylenoid species 10. Phenylsilane and diethyl-silane also gave di- and trisilanes upon treatment with L3RhCI (24). 

The Si-H bond is particularly labile under Lewis acid conditions, and when stoichiometric quantities of hydrosilanes are used, the reaction can be hazardous. For example, the redistribution of the very stable phenylsilane generates silane, which reacts explosively with air. 

The stereochemistry of the oxidative addition has been studied using optically active 1-naph-thyl(methyl)phenylsilane (11) and its deuterium derivative (10). The H/D exchange reaction of the hydrosilane proceeds with 100% retention of configuration (equation 5). Addition of the hydrosilane (11) to 1-octene gives l-naphthyl(methyl)octyl(phenyl)silane (12) with retention of the configuration of the silicon (equation 6). ... 

The silyl halides can now" be prepared in high purity and high yield by the facile hydrogen halide cleavage of the carbon-silicon bond in arylsilanes. " No catalyst is required, and the use of the hazardous intermediate reagent, silane, is avoided. Bromosilane is prepared by the reaction of hydrogen bromide and phenylsilane. The latter is obtained by lithium hydro-aluminate reduction of the commercially available phenyltri-chlorosilane. lodosilane can be prepared in a similar fashion however, mixtures of iodosilane and benzene are difficult to separate. The preferred alternative procedure described below utilizes an isomeric mixture of 2-, 3-, and 4-chlorophenylsilanes as the intermediate. This intermediate is obtained by the chlorination of phenyltrichlorosilane, and is then reduced to the hydride. 

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