Trimethylsilyl methyllithium

Reaction of tris(trimethylsilyl)methyllithium 1631 with styrene oxide affords, via 1632 and 1633, the cyclopropane 1634 in 69% yield [25] (Scheme 10.11). The reactions of tris(trimethylsilyl)methyllithium 1631 have been reviewed [26]. 

The combination of equimolar amounts of tris(trimethylsilyl)methyllithium and zinc bromide in a THF/diethyl ether mixture, Scheme 27, furnished tris(trimethylsilyl)methylzinc bromide, as a lithium bromide/ether adduct.43 The compound, which may also be formulated as a lithium alkyldibromozincate, showed no ligand redistribution reactions. It is monomeric in solution and can be treated with 1 equiv. of an organolithium reagent to afford heteroleptic diorganozinc compounds. 

The (—)-sparteine-complex of l-(2-pyridyl)-l-(trimethylsilyl)methyllithium is monomeric and shows, according to an X-ray analysis, an almost planar methine group. The lithium cation is placed in a -fashion above the plane of the azaallyl anion moiety. 

Reaction of (phenylsulfanyl)bis(trimethylsilyl)methyllithium with a (chloromethyl)oxirane afforded cyclobutanes 20 in acceptable yield.14 The proposed mechanism is shown.19... 

Methoxy(phenylthio)trimethylsilyl-methyllithium, 182 l-Methoxy-3-phenylthio-3-trimethyl-silyl-l-propenyl-3-lithium, 182 1 -Methoxy-4-(trimethylsilyl)-1 -butene-3-ynyl-2-lithium, 180 Methyllithium, 142, 188, 203, 214, 315 Methyllithium-Methylaluminum bis-(2,6-di-t-butyl-4-methylphenoxide), 203... 

However, the reaction of benzaldehyde with bis(trimethylsilyl)methyllithium gave a mixture of trans and cis isomers in a ratio of 1.4 1 (equation 128). If this reaction involved the /J-oxidosilane intermediate 158, the same stereochemical outcome would be expected. This was taken to suggest that, in this particular Peterson olefination reaction at least, the /J-oxidosilane 158 is not a major intermediate, and that the oxasiletane anion is formed directly by simultaneous formation of C—C and Si—O bonds. 

Methoxy(trimethylsilyl)methyllithium, 331 (E)-l-Methoxy-3-trimethylsilyloxy-l,3-butadiene, 332-334 Methyl 2-acety[aerylate, 334-335 Methyl acrylate, 7-8, 22, 50 Methylal, 193... 

Methoxy(phenylsulfanyl)(trimethylsilyl)methyllithium 324 has been used as acyllithium and, depending on the electrophile and the deprotection conditions, it can transfer the acyltrimethylsilyl, the methoxycarbonyl or the (phenylsulfanyl)carbonyl group. By alkylation of intermediate 324 with primary alkyl iodides, bromides and chlorides in the presence of HMPA, followed by oxidation of compound 325 with NaI04, acylsilanes... 

Tris(trimethylsilyl)methyllithium (88), prepared from methyllithium and tris(trimethylsilyl)methane in THF, can be recrystallized from toluene to give colorless, transparent needles of the unique ate complex [Li(THF)4] [Li C(TMS)3 2] . The structure of one of the anions in this complex is shown as (89). This... 

The Peterson reaction can be used to synthesize a number of heterosubstituted alkenes. Methoxydi-methylsilyl(trimethylsilyl)methyllithium (316) can be added to aldehydes and ketones, including enoliz-able substrates, to form Ae vinylsilane (317 equation 71). Modest ( ) (Z)-selectivity was observed in unsymmetrical cases. This reagent may represent an improvement over the bis(trimethylsilyl)methyl anion, which is ineffective for enolizable substrates. 

The synthesis of terminal alkenes entails addition of either (trimethylsilyl)methyl-magnesium chloride (Me3SiCH2MgCl) or (trimethylsilyl)methyllithium (Me3SiCH2Li) to an aldehyde or a ketone to yield the corresponding P-hydroxysilane, which undergoes base- or acid-mediated elimination to furnish the alkene, as exemplified below. " ... 

Prepared by Peterson olefination from tris(trimethylsilyl)methyllithium and the corresponding aldehyde, see ref [39]. 

Fleming, I., Floyd, C. D. The reactions of tris(trimethylsilyl)methyllithium with some carbon electrophiles. J. Chem. Soc., Perkin Trans. 1 1981,969-976. 

Kang, K. T., Sung, T. M., Lee, K. R., Lee, J. G., Jyung, K. K. Reactions of acylsilanes with phenylthio(trimethylsilyl)methyllithium. Competitive Peterson and Brook rearrangement-elimination reactions in the 3-thiophenyl-a, 3-disilylalkoxides. Bull. Korean Chem. Soc. 1993, 14, 757-759. 

Alkynyltrimethylsilanes. Arylethynylsilanes are obtained from aromatic nitriles by reaction with tris(trimethylsilyl)methyllithium which is in turn derived from the silane (MeLi/THF, 65°). The initial adducts eliminate lithium hexamethyldisilazide on thermolysis in benzene. 

More powerful nucleophiles bring about nucleophilic displacement of a cyclopenta-dienyl group. Stannocene reacts with 2-lithiopyridine to give the triptych product shown in equation 21-31,122 and Cp 2Sn reacts with bis(trimethylsilyl)methyllithium to give [(Me3Si)2CH]2Sn .121... 

The products obtained from the reaction of (chloromethyl)trimethylsilane with organolithium reagents depend very much on the structure of the lithium compound. While lithium 2,2,6,6-tetramethylpiperidide initiates an a-elimination as described above, the treatment with sec-butyllithium leads to the formation of chloro(trimethylsilyl)methyllithium (11). This reagent cyclopropanates an electron-deficient alkene through sequential Michael addition and intramolecular ring closure (MIRC reaction), for example, the formation of cyclopropane 12. 

Reaction of tris(trimethylsilyl)methyllithium, generated from tris(trimethylsilyl)methane and butyllithium, with phenyloxirane gave 2-phenyl-l,l-bis(trimethylsilyl)cyclopropane (1) in good yield. 

A 1 1 mixture of trans- and c -isomers 2 was obtained by the reaction of phenyl-sulfanyl[bis(trimethylsilyl)]methyllithium with phenyloxirane. ... 

Bis(phenylsulfanyl)](trimethylsilyl)methyllithium and trimethylsilyloxirane do not afford a homo-Peterson reaction product, but a cyclopropane 4 a with a shifted phenylsulfanyl group. [Bis(phenylsulfanyl)](trimethylsilyl)methyllithium may be looked on as a carbenoid species which is in equilibrium with carbene and phenylsulfonate. This equilibrium may lie towards the carbanion. On addition of trimethylsilyloxirane, phenylsulfonate is trapped with formation of an alkoxide, which corresponds to the intermediate of a Peterson olefination of formaldehyde, and leads to phenyl vinyl sulfide. This provides a reaction partner for the liberated carbene giving cw-l,2-bis(phenylsulfanyl)-l-trimethylsilylcyclopropane (4a) in a stereospecific [2-1-1]... 

Reaction of phenylsulfanyl(trimethylsilyl)methyllithium with 1,2-epoxycyclohexane or 1,2-ep-oxycyclopentane gave a trani-alkoxide which, on treatment with benzenesulfonyl chloride (0 °C, 30 min) followed by ec-butyllithium and iV.A. A. iV -tetramethylethylenediamine at 0°C, yielded 7-phenylsulfanyl-7-trimethylsilylbicyclo[4.1.0]heptane (2b) or 6-phenylsulfanyl-6-trimeth-ylsilylbicyclo[3.1. OJhexane (2a). 

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