Additions tris silane

Common synthetic pathways to obtain mono-, di-, tri- and tetraalkylsilanes are reactions of the respective halogenosilanes with lithiated alkyl compounds, with alkyl-magnesium halides (Grignard reactions) and with alkyl halides in a Wurtz-Fittig-type reaction, as well as the addition of silanes to alkenes, i.e. hydrosilylation. 

Nickel complexes formed in situ by the reaction of NiCl.S-COD) with the iini-dazolium salts IMesHCl or IPrHCl in the presence KO Bu catalyse the hydrosilylation of internal or terminal alkynes with EtjSiH. Interestingly, Ni tri-butylphosphine complexes are inactive in this hydrosilylation reaction. The monosilylated addition products were obtained with slow addition rates of the alkyne in the reaction mixture and were formed with variable degree of stereoselectivity, depending on the type of the alkyne, the silane and the ligand on Ni [50],... 

Dicyclohexyl Ether [Brpnsted Acid Promoted Reduction of a Ketone to a Symmetrical Ether].313 Cyclohexanone (3.92 g, 40 mmol) and tri(n-butyl) silane (1.78 g, 20 mmol) were placed in a round-bottomed flask. TFA (75 mmol) was added slowly over a one-hour period to the reaction mixture, which was held at —35°. After complete addition, the reaction flask was placed in a freezer at —15° for 70 hours. Direct distillation gave dicyclohexyl ether 2.91 g (16 mmol, 80%) bp 119-121718 Torr. 

In addition, commercially available phenyltrimethoxysilane has been successfully cross-coupled with heteroaryl bromides including both bromopyridines and bromothiophenes [105], Both 2-bromopyridine and 3-bromopyridine were coupled with phenyltrimethoxysilane to give the corresponding phenylpyridines in 76% and 62% yield, respectively. Employing phenyl tris(trifluoroethoxy)silane, a siloxane with electron-withdrawing groups, did not improve the yields. 

The radical source must have some functional group X that can be abstracted by trialkylstannyl radicals. In addition to halides, both thiono esters and selenides are reactive. Allyl tris(trimethylsilyl)silane can also react similarly.232 Scheme 10.11 illustrates allylation by reaction of radical intermediates with allylstannanes. 

Like monodisperse carbosiloxane dendrimers, hyperbranched carbosiloxanes can be produced by hydrosilylation [100]. The first compounds of this kind were synthesised in 1991 by Mathias and Carothers [101] by polymerisation of an al-lyl-tris(dimethylsiloxy)silane monomer with addition of chloroplatinic acid hydrate (Fig. 4.52). The reaction proceeds relatively fast however, addition of more catalyst does not increase the molecular masses (19000 g/mol). The NMR spec-... 

In addition to the seven deoxygenation and dehalogenation reactions demonstrated, the authors adapted the methodology to the hydrosilyla-tion of a series of alkynes and alkenes. To conduct such reactions, a premixed solution of the alkyne or alkene (1.00 M), tris(trimethylsilyl) silane 61 (1.2M) and AIBN 62 (10mol%) in toluene was passed through the heated microreactor (130 °C) at a flow rate of 200 jilmin-1, affording a residence time of 5 min. 

Generation of 3-indolylacyl radicals from the selenoesters 149, using either /j-Bu3SnH or tris(trimethylsilyl)silane (TTMSS) followed by reaction with various alkenes, offers a route to 3-acylindoles 150. On the other hand, the use of n-Bu Sn2 under irradiation gave cyclopent[6]indole derivatives such as 151 via a cascade involving initial addition of the acyl radical to the alkene, and a subsequent oxidative cyclization at the indole C-2 <02JOC6268>. 

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