Silyllithiums reactions with

Three different routes to the key compounds for the sila-Peterson elimination, the a-alkoxydisilanes 157, are described in the literature, namely A, reaction of silyllithium reagents with ketones or aldehydes B, addition of carbon nucleophiles to acylsilanes C, deprotonation of the polysilylcarbinols. In addition, method D, which already starts with the reaction of 2-siloxysilenes with organometallic reagents, leads to the same products. The silenes of the Apeloig-Ishikawa-Oehme type synthesized so far are summarized in Table 4. 

Methoxy-bis[tris(trimethylsilyl)silyl]methane (4) - the first compound bearing two hypersilyl groups at a carbon atom - was synthesized by the reaction of tris(trimethylsilyl)silyllithium (1) with dichloromethyl methyl ether in a yield of 35 % In view of the extreme bulkiness of the two hypersilyl substituents, the ease of the formation of 4 is really surprising. But the reaction pathway is easily understood as a consecutive replacement of the two chlorine atoms of the dichloromethyl methyl ether by the silanide 1 (Eq. 1). 

A controlled opening of a,(3-epoxy ketones involves reaction with Ph(Me)2SiLi and mild hydrolysis. Attack of the silyllithium reagent on the ketone groups is followed by a Brook rearrangement and p-elimination. " ... 

Reaction of a chlorosilane with elemental lithium, normally in an ether solvent, provides a solution of the silyllithium compound with lithium chloride as a by-product. ... 

Elimination of silanes from a-silyl alcohols. By this oxidation acylsilanes can be prepared in two steps from esters and amides reaction with silyllithiums and PCC oxidation. Secondary silyl alcohols are oxidized to aldehydes. 

An enlargement of the silicon skeleton is possible by coupling reactions with lithium metal or silyllithium reagents [4-6]. The homocoupling of tris(diethylamino)-l-chloro-l,2-dimethyldisilane results in the linear hexakis(diethylamino)-l,2,3,4-tetramethyltetrasilane [7]. After treatment with HCl the hexachloro compound could be obtained. By the reaction of aminochlorophenylsilanes with... 

Summary The synthesis of derivatives of the type [(Me3Si)3Si]2CHR (R = OH, OCH3, 0C(0)H, 0C(0)Me, NMe ) proved to be surprisingly facile and was achieved by the reaction of tris(trimethylsilyl)silyllithium (1) with suitable Ci building blocks. The results of the X-ray analyses and reactions of these di(hypersilyl) compounds are described in this paper. 

Our approach for starting material suitable as a silyl dianion synthon (D) was via the bis(diphenylmethyl)-substituted silane 15. It was selectively cleaved to give the silyllithium compound 16, which resulted, after a trapping reaction with chlorotrimethylsilane, in disilane 17 (Scheme 3 yield of 17 80 %). The isolated and purified disilane 17 then was cleaved at the Si-C bond with lithium metal, resulting in the lithiated silane 18. Another trapping reaction with chlorotrimethylsilane gave the trisilane 19 (yield of 19 78 %). 

Furthermore functionalized and chiral diphenylmethyl-substituted compounds, like rac-20, are potential precursors for enantiomerically enriched silyllithium compounds [7, 8]. They can be transformed selectively and in good yields to systems of type rac-21. A trapping reaction with chlorotrimethylsilane resulted in the products rac-22 (yield of rac-22 89 %) and 14 (Scheme 4). 

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