Tris silane products

In an effort to identify a more stereoselective route to dihydroagarofuran (15), trimethylsilylated alkyne 17 was utilized as a substrate for radical cyclization (Scheme 2). Treatment of 17 with a catalytic amount of AIBN and tri-n-butyltin hydride (1.25 equiv) furnishes a mixture of stereoisomeric vinyl silanes 18 (72% combined yield) along with an uncyclized reduction product (13% yield). The production of stereoisomeric vinyl silanes in this cyclization is inconsequential because both are converted to the same alkene 19 upon protodesiiyiation. Finally, a diastereoselective di-imide reduction of the double bond in 19 furnishes dihydroagaro-... 

To prepare multifunctionalized symmetric organosilicon compounds by the polyalkylation of benzene. (2-chloroethyi)trichlorosilane and (3-chloropropyl)tri-chlorosilane were reacted with benzene. Polyalkylations of benzene with (2-chloroethyl)silane and (3-chloropropyl)silane were carried out in the presence of aluminum chloride catalyst at a reaction temperature of 80 C. The reaction of benzene with excess (2-chloroethyI )trichlorosilanes afforded pcralkylated product, hexakis(2-(trichlorosilyl)ethyl)benzene in good yield (70%). ... 

As shown in Table XIV, the reactivity of (trichloromethyl)silanes varied depending upon the substituent on silicon. The reactivity and yields of (trichloromethyl)-methyldichlorosilanes were slightly higher than those of (trichloroinethyl)tri-chlorosilanes in the aluminum chloride-catalyzed alkylation as similarly observed in the alkylations with (ai-chloroalkyl)silanes and (dichloroalkyl)silanes. The electron-donating methyl group on the silicon facilitates the alkylation more than the electron-withdrawing chlorine. The minor products, (diphenylmethyl)chloro-silanes, were presumably derived from the decomposition of (triphenylmethyl)-chlorosilanes. 

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],... 

These reactions result in iodine atom transfer and introduce a potential functional group into the product. The trialkylborane method of radical generation can also be used in conjunction with either tri-n-butyl stannane or fnT-(trimethylsilyl)silane, in which case the product is formed by hydrogen atom transfer. 

Natural products containing a spiropyrrolidinyloxindole nucleus have recently found to exhibit interesting biological activity such as cell-cycle inhibition [23]. This observation encouraged Murphy and coworkers to design a novel domino route to ( )-horsfiline (3-43), a natural spiropyrrolidinyloxindole (Scheme 3.13) [24]. Treatment of azide 3-39 with tris(trimethylsilyl)silane (TTMSS) and AIBN as radical starter led to the radical intermediate 3-40 after a first ring closure, which under-... 

Tricyclic derivative 186 was obtained by treating solution of 184 with tris(trimethylsilyl)silane (TTMSS) and azobisisobutyronitrile (AIBN). The pyridyl radical 185 is the suggested intermediate product (Scheme 4)... 

When 349 is generated thermally at 140 °C from mesitoyl-tris(trimethylsilyl)silane, the silyl enol ether 472 was isolated as the sole product". 472 results from isomerization of the siloxetane 470 (equation 156)". 

The same product was obtained in 52% yield along with considerable amounts of l,2,2-triphenyl-l-(trimethylsilyl)ethene (22%) when the benzoyl-tris(trirnethylsilyl)silane was thermolysed in the presence of benzophenone". 

A third photochemical access to silylenes, beside the isomerization of silenes and the photolysis of tri- or cyclopolysilanes, is the irradiation of geminal diazidosilanes, which under nitrogen loss often gives the corresponding divalent silicon species. However, silan-imines are frequent by-products164 or in some cases even the only products (Section IV). 

Tris(trimethylsilyl)silyl radical is relatively stable and can therefore serve as a radical leaving group. This reaction has been extended to the radical-initiated allylation of organic halides202 203. Thus, thermolyses of bromides a to a carbonyl substituent 144 or of simple iodides with allyltris(silyl)silane in the presence of a radical initiator gives the corresponding allylation products (equation 112). 

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