Silyllithiums

Dimethyl-phenyl-silyllithium eignet sich zur trans-stereospezifischen Deoxygenierung von Oxiranen zu Alkenen (Carbonyl-Gruppen storen die Reaktion)5 ... 

The stable (f-Bu2MeSi)3Si radical reacts with lithium in hexane at room temperature affording the silyllithium 7, with the central anionic silicon atom almost planar, whereas the one-electron oxidation with tiiphenylmethyl ion produces the corresponding silylium ion 8 (Scheme... 

Reduction of the Si-Si bond of oligosilanes with organo- or silyllithium reagents (Scheme 2.44, A,... 

Silyl Anions with Functional Groups (Hydrido)silyllithiums ... 

Kawakami et al. have prepared optically active bifunctional l,3-dimethyl-l,3-diphenyldisiloxanes.158,159 Strohmann et al. have prepared enantiomerically enriched Si-centered silyllithium compounds, which react stereo-specifically with triorganochlorosilanes.160-162 In solution, slow racemization of the silyllithium compounds takes place, which, however, can be circumvented by transmetallation with MgBr2. Oestreich et al. prepared new Si-centered cyclic silanes adopting the strategies developed by Corriu and Sommer.163 Bienz et al. have developed enantioselective routes for the preparation of C-centered chiral allenylsilanes.156,164-166... 

More recently, Kira et al. have published a new route to the preparation of hydrido(trialkylsilyl)silyllithiums, such as (/-BuMe2Si)2SiHLi 160,298 which show promise as versatile starting materials in organometallic synthesis. 

Tetraalkyl- or tetrasilyltetragallium(I) compounds were also obtained by the reactions of the dioxane adducts of Ga2X4 (X = Cl, Br) with bulky alkyl- or silyllithium compounds [Eq. (5)], which were accompanied by disproportionation of Ga(+2) to Ga(+1) and Ga(+3) [44, 45], In particular the yield of the alkyl derivative 21 was very poor and several unknown byproducts were detected by NMR spectroscopy. Furthermore, the reaction requires the employment of a solvent-free lithium compound, which is not readily available. The reaction of tris(trimethylsilyl)silyl lithium yielded the expected product of the disproportionation [(Me3Si)3Si]2GaCl2Li-(THF)2 besides compound 11. 

Scheme 3.27. Regioselectivity in reactions of silyllithium and silyl cuprate reagents with allylic carbamates and epoxides...

The reaction of (t-Bu2MeSi)3Si radical with lithium in hexane at room temperature afforded the silyllithium 16 for which the crystal structure shows... 

This chapter will concentrate mainly on the chemistry of silyllithium compounds, i.e. neutral tetravalent silyl compounds bearing one or more lithium substituents at silicon. In addition, the chemistry of other organosilicon compounds containing alkaline and alkaline earth metals will be outlined in this chapter. 

The synthesis of silyllithiums containing two aromatic substituents and a hydrogen has been accomplished by the reaction of A SiHCl (Ar = Ph40, Mes44) with lithium metal or lithium l-(dimethylamino)naphthalenide (LDMAN)45 in THF. This reaction is assumed... 

Silenolates 26, i.e. silicon analogues of enolates, are formed, as shown by Ishikawa and coworkers, when sterically congested tris(trimethylsilyl)acylsilanes 25 are treated with silyllithium compounds (Scheme 10)87a b c The silyllithium reagent does not add to the C=0 bond but exclusively cleaves a Si—Si bond, yielding the corresponding silenolate 26. 

Amino-substituted silyllithium compounds have been prepared by Tamao and coworkers from the corresponding chlorosilanes by treatment with either a dispersion of lithium metal... 

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