Silanes trialkyl

Silicones Dimethyl sihcone, trialkyl and tetraalkyl silanes Lubricating oils distillation fermentation jam and wine making food processing... 

Lithium silylamides react smoothly with tiifluoronitrosomethane to give diazenes Traces ot water initiate the decomposition of the latter with liberation of a trifluoromethyl carbanion, which is trapped by carbonyl compounds [775] (equation 116) Desilylation of trialkyl(trifluoromethyl)silanes by fluoride ion produces also a trifluoromethyl carbanion, which adds to carbonyl carbon atoms [136, 137] (equations 117 and 118)... 

Preparation of [l-(diethoxyphosphinyl)ethoxy]dimethyl-silane — Reaction of an aldehyde with a trialkyl phosphite in the presence of a silyl halide... 

Cyclization of a 1,6-enyne to a methylenecyclopentane can be effected with a Pd(0) catalyst complexed with a phosphine ligand in combination with a trialkyl-silane as a hydride donor (equation I).4 Under these conditions a 1,7-enyne can be cyclized to a methylenecyclohexane. 

Table I includes the relative bond dissociation enthalpies obtained for some group 14 hydrides by photoacoustic calorimetry,7 10 The data demonstrate that, for the trialkyl-substituted series, the bond strengths decrease by 6.5 and 16.5 kcal/mol on going from silane to germane and to stannane, respectively. The silicon-hydrogen bonds can be dramatically weakened by successive substitution of the Me3Si group at the Si-H functionality. A substantial decrease in the bond strength is also observed by replacing alkyl with methylthio groups.

Die der N-Alkylierung entsprechende N-Silylierung von primaren und sekundaren Aminen mittels Chlor-trimethyl-silan oder auch anderen Halogen-trialkyl-silanen ist in Bd. XIII/5, S.228ff., und in Bd. E4, S. 721 f., abgehandelt. 

Alcoholysis of R3SiH.1 Rhodium(II) perfluorobutyrate is more effective than Rh2(OAc)4 as a catalyst for reaction of primary or secondary alcohols with trialkyl-silanes at 25° to form silyl ethers. Tertiary alcohols are inert under these conditions. Selective reactions with only primary alcohols can be realized with r-butyldimethyl-silane but not with dimethylphenylsilane. 

In related chemistry, the borane/silane catalytic system can cleanly dealkylate phosphonic and phosphinic esters RPO(OR,)2 or R2PO(OR/) to give silyl esters with trialkyl silanes.259 If more active silane reagents like Ph2SiH2 or PhSiH3 are employed, catalytic reduction to primary or secondary phosphines is observed. Mechanistic experiments strongly support a silane activation pathway for this chemistry. 

As we have already mentioned, ruthenium complexes predominantly catalyze the dehydrogenative silylation of alkenes but competitively with the hydrosilylation so the reaction usually gives a mixture of the dehydrogenative silylation and hydrosilylation products. Ru3(CO)12 appears to be a very active catalyst for the dehydrogenative silylation of styrene, para-substituted styrenes [ 19, 20],trifluoropropene and pentafluorostyrene [21] by trialkyl-, phenyldialkyl-silanes (but also triethoxysilane) (Eq. 10). 

Die Reaktion laBt sich so modifizieren, daB man den Phosphinigsaure-methylester in Ge-genwart eincs Chlor-trialkyl-silans mit der Carbonyl-Verbindung umsetzt167 l68 ... 

Austausch von Methyl-Gruppen in Phosphorsaure-dimethylester-halogeniden gegen Trialkylsilyl-Gruppen mittels Brom-trialkyl-silan in Dichlormethan318 ... 

Aus Phosphorsaure-amid-dialkylestern erhiilt man unter milden Bedingungen mit einem Mol Brom- bzw. Jod-trialkyl-silan in guten Ausbeuten Phosphorsaure-alkylester-amid-trialkylsilylester, mit 2 Mol Silan -amid-bis-[trialkylsilylester]668 z.B. ... 

Indium-mediated allylation of trialkyl(difluoroacetyl)silane 70 in aqueous media gives homoallylic alcohol 71 exclusively (Scheme 60). Both water and THF are essential for the allylation reaction. It is worth noting that homoallylic alcohol 71 is formed exclusively under these reaction conditions. On the contrary, enol silyl ether 72 is a major product of the fluorinated acylsilanes reaction with other organometallic compounds than indium via a Brook rearrangement and defluorination. Indium-mediated allylsilylation of carbonyl compounds provides a facile route to 2-(hydroxyethyl)allylsilanes. The allene homologs are similarly prepared (Scheme 61).244,244a... 

The measured 29Si NMR chemical shift of 59 in benzene solution is 111 ppm, which was considered to indicate strong silylium ion character of 59 in solution. [7,9] This was based on the fact that the parent silane, (Me3Si)3SiH, possesses a shift value (-119.6 ppm, Table 8) which is 230 ppm more upfield than that of 59, which is large in comparison to the corresponding difference in shift values for silylium cations and parent silanes observed in the case of trialkyl substituted systems. 

Trialkyl(pcrfluoroalkyl)silanes react with carbonyl-containing compounds in the presence of the fluoride of an alkali metal or ammonia in an aprotic bipolar solvent at — 45 up to 120 C... 

Trifluoromethylated phenols and anilines have been made by reaction of ortho- and pani-quinoncs with trialkyl(trifluoromethyl)silanes, under base catalysis with subsequent reduction or reductive amination of the reaction products. 

Vinylsilanes 227 in various ElZ ratios are formed in high yields in the reactions of acyl(trialkyl)silanes 225 with anions generated from tetrazolyl sulfones 226 <03OL2789>. The synthesis and chemistry of tetrazolylacroleins has been reported <03T7485>. Fused tetrazole derivatives were obtained from intramolecular iodocyclization of tetrazolyl olefins <03T6759>. 

---