Silanes preparation

Efficient asymmetric transfer is also observed for 1,2-benzenediol induced reactions of a-sub-stituted (Z)- and ( ,)-allyl(trialkoxy)silanes prepared by hydrosilation of conjugated dienes, although in this case the electrophile attacks the C-C double bond of the allylsilane syn with... 

The silane, prepared by reduction of tris(2-propylthio)silylenium perchlorate with diisobutylaluminium hydride at —78°C, is subsequently isolated by high-vacuum distillation from the mixture. Heating must be very mild to prevent explosion. 

Dining preparation of tris(ketoximino)silanes, two violent explosions attributed to acid-catalysed exothermic rearrangement/decomposition reactions occurred. Although these silane derivatives can be distilled under reduced pressure, the presence of acidic impurities (e.g. 2-butanone oxime hydrochloride, produced during silane preparation) drastically reduces thermal stability. Iron(III) chloride at 500 ppm caused degradation to occur at 150°, and at 2% concentration violent decomposition set in at 50°C. 

Nitrogen-containing compounds Organotris(alkylhydroperoxy)silanes, preparation, 782... 

TABLE 1. Physical Properties of Poly(isobornyl methacrylate-co-isobornyl acrylate)-co-methacryloxypropyl-tris(trimethylsiloxy)silane Prepared According to Current Application... 

One of the simplest methods for preparation of an a,/J-unsaturated acyl silane is by hydrolysis of a 1-alkoxy-l-trimethylsilylbutadiene, the conjugated dienol ether of a,fi-unsaturated acyl silane, prepared by deprotonation and alkylation of the 1-alkoxydiene (Scheme 42)11. This method is generally limited in application to simple substrates, presumably due to the complexity of preparation of more highly functionalized 1-alkoxy dienes. 

Heating 4- and 5-bromoacyl silanes at 100 °C in a polar aprotic solvent induces cyclization through the enol forms to give 2-silyldihydrofurans and 2-silyldihydropyrans, respectively195. Similar transformation of 4- to 7-halothioacyl silanes, prepared from the corresponding haloacyl silanes by reaction with hydrogen sulphide, but induced by sodium hydroxide, gave the 2-silylated sulphur heterocycles in excellent yields (Scheme 84)196. Intermolecular enolate reactions of acyl silanes are also known (vide infra, Section IV.A.6). 

Oligoacetylenic silanes, preparation, 3, 433 Oligocenes, via zinc reagents, 9, 121 Oligoferrocenes, preparation, 12, 322... 

Aldol Addition. A catalyst generated upon treatment of Cu(OTf)2 with the (5,5)-r-Bu-box ligand has been shown to be an effective Lewis acid for the enantioselective Mukaiyama aldol reaction. The addition of substituted and unsubstituted enolsilanes at -78 °C in the presence of 5 mol % catalyst was reported to be very general for various nucleophiles, including silyl dienolates and enol silanes prepared from butyrolactone as well as acetate and propionate esters. 

Finally, reaction of -butyl lithium with tris(tert-butylamino)silane prepared in high yield from trichlorosilane and excess tert-butylamine, gives the completely lithiated silazane 4. An X-ray structure determination shows the compound to be dimeric in the solid (Fig. 4). While six lithium and two silicon atoms build up the inner cube of a rhombic dodecahedron, six nitrogen atoms occupy the remaining vertices. Compounds with an analogous structure have been reported by several research groups [2, 7, 15]. 

Trisilane. Trisilicopropane trisilicon octahydride silicopropane trisilicane. HtSi9 mol wt 92.33. H 8.73%, Si 91.27%. SijHj. Obtained by separation of mixed silanes prepared from magnesium silicide and hydrochloric acid Stock. Somlesky. Ber. 49, 111 (1916) 54B, 524 (1921) S6B, 247 (1923) Culbertson. UA pat. 2,551,571 (1951 to Union Carbide) prepared by conversion of silane to higher silanes in an ozonizer type of electric discharge Spanier, MacDiar-mid, In org. Chem. 1, 432 (1962). 

Monomer synthesis. Dichloro[p-(S)-2-methylbutylphenyl](p- -butylphenyl)si-lane (1) is prepared by lithiation of p-(S)-2-methylbutylphenylbromide in dry diethylether at 0 °C. The resulting aryl lithium ether solution is added to an equimolar amount of trichloro(p-n-butylphenyl)silane (prepared by addition of p-M-butylphenyl lithium to silicon tetrachloride) in dry -hexane (Chart 13.24). 

Substituted allenes are obtained from the reaction of propargyl silanes (prepared from lithium alkynes and trimethylsilylmethyl chloride ) and electrophiles. An exocyclic allene is produced when this reaction involves ring closure, a method which has been applied in a biomimetic steroid synthesis (Scheme 16). ° If the corresponding trimethylsilylalkyne is used a D-homosteroid system is obtained. ... 

Napthyl dimethyl (dimethylamino) silane (preparation). A10% solution of 1 equiv monochlorosilane (naphthyl dimethyl chlorosilane) in hexane (in benzene if necessary for solubility reasons) is stirred in a flask equipped with a reflux condenser cooled at -20 °C. From a communicating flask 2.2 equiv of dimethylamine vapour is slowly introduced over the solution and the mixture kept at room temperature overnight. After filtration and evaporation of the solvent, the residue is distilled. 

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