Tris trimethylsilyl silane

Trisyl bromide is very reactive toward lithium, magnesium, and phenyllithium to give the corresponding organometallic reagents. These reagents are useful in the Peterson alkenation reaction. 

Hideki Sakurai Tohoku University, Sendai, Japan 

Metalation. Tris(trimethylsilyl)methyllithium can be prepared by metalation of tris(trimethylsilyl)methane by methyl-lithium in a mixture of diethyl ether and THF (eq 2). An improved procedure is described as follows. To a solution of tris(trimethylsilyl)methane in THF is added a solution of MeLi (10% excess) in diethyl ether with stirring under nitrogen. The diethyl ether is distilled off and the residual solution is boiled under reflux under nitrogen. After 2 h, about 95% of tris(trimethylsilyl)methane is converted to tris(trimethylsilyl)methyllithium. Tris(trimethylsilyl)-methyllithium is important for the introduction of (Mes Si)3C (trisyl) groups, and for use in Peterson alkenations (eq 3). 

Formation of Bis(trimethylsilyl)methyllithium. The carbon-silicon bond of tris(trimethylsilyl)methane can be cleaved by lithium methoxide in HMPA to formbis(trimethylsilyl)methyl-lithium, which subsequently reacts with carbonyl compounds to form alkenes (eq 4).  

Similar cleavage of the Si-C bond occurs with fluoride ion. The in situ reaction with carbonyl compounds gives the corresponding alkenes. Thus the reaction of tris(trimethylsilyl)methane with nonenolizable carbonyl compounds in the presence of tris(dimethylamino)sulfonium difluorotrimethylsilicate (TASF) gives the corresponding alkenes in excellent yield (eq 5).  

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Heteropolycyclic compounds were obtained [29] by treating bromo furylethers with tris-(trimethylsilyl)silane (TTMSS) in hot toluene containing a catalytic amount of AIBN (Equation 1.12). 

Chatgilialoglu, C. Ferreri, C. Gimisis, T. Tris(trimethylsilyl)silane in organic synthesis. In Rappoport, Z. Apeloig, Y. (Eds.), The Chemistry of Organic Silicon Compounds, Wiley, Chichester, 1998 Vol. 2, Chapter 25, pp. 1539-1579. 

For the use of tris(trimethylsilyl)silane instead, see Giese, B. Kopping, B. Chatgilialoglu,... 

Reduction by hydrogen atom donors involves free radical intermediates and usually proceeds by chain mechanisms. Tri-n-butylstannane is the most prominent example of this type of reducing agent. Other synthetically useful hydrogen atom donors include hypophosphorous acid, dialkyl phosphites, and tris-(trimethylsilyl)silane. The processes that have found most synthetic application are reductive replacement of halogen and various types of thiono esters. 

Tris(trimethylsilyl)silane (1,1,1,3,3,3-Hexamethyl-2-(trimethylsilyl)trisilane) [1873-77-4] C9H28Si4... 

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-... 

Another anti-cancer agent in clinical use is podophyllotoxin (3-59) this has an aryl tetrahydronaphthalene lignan lactone skeleton, and demonstrates potent tubulin-binding, anti-mitotic properties (Scheme 3.16) [30]. The Sherburn group [31] prepared this molecule by a tris(trimethylsilyl)silane promoted conversion of thionocarbonate 3-55 into the lactone 3-58, which proceeded with a yield of 38 %. As intermediates, the radicals 3-56 and 3-57 can be assumed. 

In this way, various pentacycles 3-210 could be obtained in yields of 51 to 63 % (Scheme 3.54). It should be noted that toxic tin organyls could be replaced by silanes such as tris(trimethylsilyl) silane, but under these conditions the reaction rate was significantly reduced. 

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)... 

The action of a catalytic amount of triethylborane on tris(trimethylsilyl)silane induces the formation of tris(trimethylsilyl)silyl radicals, which promote the ring-closure of 1,6-heptadiene to a mixture of the cis- and rirms-cyclopcntanc derivatives 115, together with a small amount of the silicon heterocycle 116 (equation 61)68. 

Diastereoselective syntheses of dihydrobenzo[f>]furans have been accomplished by a rhodium-catalyzed regioselective and enantiospecific intermolecular allylic etherification of o-iodophenols as a key step, providing the corresponding aryl ally ether 122, which leads to a dihydrobenzo[b]furan by treatment of the intermediate aryl iodide with tris(trimethylsilyl)silane and triethylborane at room temperature in the presence of air <00JA5012>. 

A new effective metal-ffee radical approach by Murphy et al generates the free radical by treatment with tetrathiafulvalene (TTF).1491 As depicted in scheme 16 the aromatic amine 79 is transformed into the diazonium salt 81 which on treatment with TTF leads to the radical 82. The following stereoselective cyclization gives the hexahydrocarba-zole scaffold 80, a substructure of alkaloids like aspi-dospermidin, strychnin and vinblastin. Also the non-toxic tris(trimethylsilyl)silane was employed for domino reactions, eg. for the preparation of the alkaloid aspidospermidin. 

Tris(trimethylsilyl)silane [20,21], thiols [22], germanes [23-25] and gallium hydride [26] can be added easily to terminal alkynes in the presence of Et3B/02. This process was extended to internal alkenes (Scheme 8, Eq. 8a) as well as silyl enol ethers (Eq. 8b) by using tri-2-furylgermane. In this last case, basic or acidic treatment of the main syn /J-siloxygcrmanc furnishes the corresponding E- or Z-alkene, respectively [24],... 

Tris(trimethylsilyl)phosphine, 3229 Tris(trimethylsilyl)silane, 3231... 

Tris(trimethylsilyl)silane reacts with phosphine sulfides and phosphine selen-ides under free radical conditions to give the corresponding phosphines or, after treatment with BH3-THF, the corresponding phosphine-borane complex in good to excellent yields (Reaction 4.45) [82]. Stereochemical studies on P-chiral phosphine sulphides showed that these reductions proceed with retention of configuration. An example is given in Reaction (4.46). 

Allyl tris(trimethylsilyl)silanes are obtained in high yields from the reactions of unsubstituted and 2-substituted allyl phenyl sulfides with (TMS)3SiH... 

The combination of allylic amination, ring-closing metathesis, and a free radical cyclization provides a convenient approach to the dihydrobenzo[b]indoline skeleton, as illustrated in Scheme 10.10. The rhodium-catalyzed aUylic amination of 43 with the lithium anion of 2-iodo-(N-4-methoxybenzenesulfonyl)arrihne furnished the corresponding N-(arylsulfonyl)aniline 44. The diene 44 was then subjected to ring-closing metathesis and subsequently treated with tris(trimethylsilyl)silane and triethylborane to afford the dihydrobenzojhjindole derivative 46a in 85% yield [14, 43]. 

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