Silylated methanes

Similarly, dimethylamino-bis[tris(trimethylsilyl)silyl]methane has been obtained.198... 

Cadmium was a good promoter for this reaction, while zinc was found to be an inhibitor. Thus, the reaction of elemental silicon with a 1 4 gaseous mixture of methylene chloride and hydrogen chloride at 280 °C using copper catalyst and cadmium promoter afforded bis(silyl)methanes consisting of bis(dichlorosilyl)methane (36%), bis(dichlorosilyl)(trichloro-silyl)methane (31%), and bis(trichlorosilyl)methane (7%).22... 

In the reaction using cadmium promoter, the selectivity for tris(chloro-silyl)methane 8b was the highest among the four tris(chlorosilyl)methanes 7b-10b and about 73% in the distribution of their four compounds. These are consistent with the results observed for the direct reactions of silicon with (chloromethyl)silanes,20,21 allyl chloride,27 methylene chloride,22 and chloroform.23... 

The direct reaction of (trichloromethyl)chlorosilanes was applied under the same reaction condition described in the direct reaction of elemental silicon with (dichloromethyl)chlorosilanes above. In this reaction, an admixed gases of hydrogen chloride and 40 wt% (trichloromethyl)chlorosilanes in toluene injected using a syringe pump in pre-heater zone was fed into a reactor charged with elemental silicon (90%) and copper catalyst (10%) (Fig. 1). This reaction afforded no tetrakis (chlorosilyl)methane instead, tris(silyl)methanes and bis(silyl)methanes were obtained, which were the same products derived from the reactions of (dichloromethyl)chlorosilanes or chloroform, and (chloromethyl)chlor-osilanes or methylene chloride, respectively. This result may be rationalized by decomposition of (trichloromethyl)chlorosilanes to (dichloromethyl)-chlorosilanes and (chloromethyl)chlorosilanes on silicon-copper contact mass during the reaction, followed by reaction with elemental silicon to afford the products or the decomposition tetrakis(silyl)methane products.16... 

Abstract New polymeric supports, that can be used for preparation of novel catalytic systems, were obtained by grafting poly(vinylmethyl-co-dimethyl)siloxane arms onto multifunctional carbosilane moieties which belong to the class of exceptionally sterically hindered tris(silyl)methanes (Tj,.). Three types of Tj, molecules were applied 3-functional HCCSiMe Br) (type A), 9-functional HC[SiMe2(CHj)j-C (SiMejBr) ] (type B) and 4-functional Tg -derivative [SiMe2C(SiMe2Br)j]j (type C). The periphery-functionalized carbosilane-siloxane materials offer uniformly distributed and accessible sites for coordination of active catalytic species. New catalytic systems were thus prepared by coordination of platinum to vinyl moieties of the reported polymers, and used in hydrosilylation of vinyltrimethylsilane with 1,1,3,3-tetramethyldisiloxane. 

Both compounds 5 and 8 readily react with primary amines giving the corresponding tris(amino-silyl)methanes and -silanes (Scheme 2). 

Methoxy-bis[tris(trimethylsilyl)silyl] methane The First Geminal Di(hypersilyl) Compound... 

Summary Methoxy-bis[tris(trimethylsilyl)silyl]methane (4), the first geminal di(hyper-silyl) compound with a central carbon atom, was prepared by the reaction of tris(tri-methylsilyl)silyl lithium with dichloromethyl methyl ether. The structure of 4, which is characterized by considerable distortions due to the spatial demand of the two (MesS aSi groups, is discussed on the basis of an X-ray crystal structure analysis. 

Methoxy-bis[tris(trimethylsilyl)silyl]methane (4) - the first compound bearing two hypersilyl groups at a carbon atom - was synthesized by the reaction of tris(trimethylsilyl)silyllithium (1) with dichloromethyl methyl ether in a yield of 35 % In view of the extreme bulkiness of the two hypersilyl substituents, the ease of the formation of 4 is really surprising. But the reaction pathway is easily understood as a consecutive replacement of the two chlorine atoms of the dichloromethyl methyl ether by the silanide 1 (Eq. 1). 

Eq. 1. Synthesis of methoxy-bis[tris(triniethylsilyl)silyl]methane (4). 

Recently Yoshida et al. have employed silyl-stabilized a-alkoxy organolithium reagents for the synthesis of a variety of carbonyl compounds. Methoxy(trimethylsilyl)methane and methoxybis(trimethyl-silyl)methane, when deprotonated with Bu Li and Bu"Li respectively, give anions which can be alkylated with a variety of electrophiles. Electrolysis of a solution of the alkylated product in methanol yields, by virtue of the reduced oxidation potential of ethers a-substituted with silicon, either the dimethyl acetal or in the latter case the orthoester. The mildness of the electrolytic process recommends the method for the preparation of a variety of carbonyl compounds. 

Table 3. Silylcyclopropanes 7 by Catalytic Cyclopropanation of Alkenes with Diazo(trimethyl-silyl)methane (1)...

Bis(diisopropylamino)phosphanyl(trimethylsilyl)diazomethane 6, easily available by treatment of chlorobis(diisopropylamino)phosphane with lithiated diazo(trimethy silyl)methane, provides upon flash thermolysis at 250°C the so-called stable carbene 7.38-39-40 it behaves partly as a nucleophilic carbene and reacts only with electron-deficient alkenes such as methyl propenoate or diethyl fumarate under cyclopropanation.41 In the former case only the Z-isomer 8 is formed. Cyclopropane 9 is thermally unstable and is, therefore, oxidized in situ at the phosphorus atom with elemental sulfur to provide cyclopropane 10. Cyclopropanes 8 and 9 are also generated from the diazo compound 6 and the appropriate alkene by photolysis.41... 

Chlor-athan- -chlorid 167 (Chlor-dimethyl-silyl)-methan- -chlorid 169... 

Several groups have studied the feasibility of metalating the weakly acidic methylsilanes to form the corresponding silylmethyllithium compounds, a process of considerable theoretical and synthetic interest. Peterson (25) studied a three-day reaction between BuLi-TMEDA and tetramethylsilane at room temperature. Derivatization of the reaction mixture with trimethylchlorosilane gives a 36% yield of bis (trimethyl-silyl) methane and an 18% yield of a product resulting from partial... 

Following the outlined concept we succeeded in synthesizing methoxy-bis[tris(trimethylsilyl)silyl]-methane (2) by the reaction of 1 with dichloromethyl methyl ether (molar ratio 2 1) [1]. The reaction of 1 with ter -butyl formate (2 1) afforded di(hypersilyl)methanol (3). Despite the extreme steric shielding, the alcohol 3 is reactive and was converted with acetyl chloride into the acetate 4 and underwent transesterification with methyl formate to give 5 [2]. Recently we obtained... 

Preparative Methods deprotonation of bis(2-pyridyldimethyl-silyl)methane by n-butyllithium in dry Et20 at —78 °C under argon. 

The organolithium reagent (1) also reacts with a wide variety of other electrophiles, including silyl chlorides to provide bis(silyl)methane derivatives, and nitriles to provide -sUyl amines after in situ reduction of the intermediate imine derivative. a-Silyl epoxides are opened to provide the substituted vinylsilane. Reaction of (1) with arenesulfonyl fluorides provides a-silyl sulfones, key intermediates for the preparation of vinyl sulfones. Reaction of the lithium reagent (1) with alu-... 

Preparative Methods the reaction of chlorotrimethylsilane, lithium metal, and chloroform in THE gives tris(trimethyl-silyl)methane. ... 

TETRA(SILYL)METHANE, (H3Si)4C, A VOLATILE CARBOSILANE FOR THE CHEMICAL VAPOR DEPOSITION OF AMORPHOUS SILICON CARBIDE THIN FILMS... 

Therefore, attempts have been made to replace methane in the feedstock mixture of gases by carbosilanes with a smaller number of C—H bonds. Relevant candidates are methylsilane, di(silyl) methane, tri(silyl)methane, and tetra(silyl)methane C(S1H3) H4 with n = 1 — 4. The latter, n = 4 for C(SiH3)4, is the most attractive species since it is devoid of C—H bonds and the carbon atom is already surrounded only by silicon atoms (4—9). 

In the reaction flask, lithium aluminum hydride (14.4 g, 38 mmol) and benzyltriethylammonium chloride (2.9 g, 13 mmol) are dispersed in tetralin (450 mL) with stirring imder nitrogen. The product of Step 4 (63 mmol of (BrSiH2)4C and toluene) is added dropwise with stirring. The mixture is stirred for 70 h at room temperature, followed by 5 h at 60°C. Toluene and tetra(silyl)methane are then condensed out of the reaction mixture kept at 60°C in a vacuum and collected in a trap held at 10°C. (Small amounts of silane are trapped in a small final trap at -196°C. From there it is allowed to escape through a safety valve to burn upon careful warming of the trap.) The liquid is subjected to fractional distillation and the product collected at 89.5°C, 4.3 g yield (50%). It solidifies in the receiver as colorless cubic crystals, mp 38°C. NMR (benzene-de) 3.84 (s, SiHs) -39.0 (t dez), J(SiC) 31.3, J(CSiH) 5.5) Si -47.8 (q dez), J(SiH) 205.7, J(SiCSiH) 4.6). MS 137-124 (CSi4HJ. 

The molecular structure of tetra(silyl)methane has been determined in the gas phase by electron diffraction. The molecule has the standard point group T symmetry (neopentane type) with a Si—C—Si—H torsion angle of 20.04° [Si—C 1.8751(7), Si—H 1.486(4) A, C—Si—H 108.5(6)°]. Crystals are cubic with space group F43m and Z = 4. Owing to the extremely small number of observed reflections, a detailed refinement of the crystal structure was not possible. 

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