Methyl silyl

Besides protonation, the dianion can be trapped by methylation. silylation and acylation, always leading to the corresponding 1,4-dihydro derivative very cleanly at low temperature. 

The predictions of the reactivities by the geminal bond participation have been confirmed by the bond model analysis [103-105] of the transition states and the calculations of the enthalpies of activation AH of the Diels-Alder reaction [94], the Cope rearrangement [95], the sigmatropic rearrangement [96], the Alder ene reaction [100], and the aldol reaction [101] as are illustrated by the reactions of the methyl silyl derivatives in Scheme 38 [102], The bond is more electron donating than the bond. A silyl group at the Z-position enhances the reactivity. 

Studies of Equilibria and Shift Reagents.—N.m.r. studies of the exchange of halogen in boron trihalide adducts of trimethylphosphine, its oxide, and sulphide,49 and exchange of chloro- and methoxy-groups between methylphosphino and methyl-silyl or -germyl moieties,80 have been reported. The rates of ionization of phosphoranes... 

In the same way 2-47 and 3-47a dialkylamino alcohols were methylated, silylated and stannylatcd via chiral x-lithiated carbamate sparteine complexes (>95- >98% ee), as well as 1,3-propanediol and 1,4-butanediol (95 >99.5% ee)45. 

Si(C6H5)3-CH3 2-[Dimethylamino-( diphenyl-methyl-silyl)-methyi -... 30 0. .(diphenyl-me-thyl-silyl)-meth-y/J--. 3 64 40 0 0 0. ..-( diphenyl-methyl-silyl)-phenyl-... 0 9... 

This method has successfully been applied for the addition of chloro(l-chloro-2,2-dimethylvinyl)carbene — formed from 1,1,2-trichlo o-3,3-dimethylcyclopro-pane by dehydrochlorination and subsequent ring-opening — onto ketene methyl silyl acetals, the products of which are transformed to interesting allenic esters when treated with tetrabutylammonium fluoride [149]. 

Unconjugated LCA, iso-LCA, DCA, iso-DCA, CDCA, CA, 12-oxo-DCA, and internal standard (HDCA) are weighed into a vessel and dissolved in ethyl acetate as stock solutions. A stock solution with standard specific concentrations (0.05-2 mg/ ml) is prepared. Each of the six calibration standards is obtained by diluting the stock solution, whereas the concentrations of the analytes are one-half, one-quarter, one-eighth, etc. Aliquots of each solution are methylated, silylated, and resolved in decane, as described in sample preparation. The concentration of the internal standard HDCA (m/z= 81.2) is 0.5 mg/ml in each of the calibration standards. 

Dimethoxy-methyl-silyl)-meth-oxy]-1-fluoro- ElOa, 602 (Educt)... 

More recently, 3,3-dimethyl-1 -trimethylsilylcyclopropene was metallated using lithium diisopropylamide (LDA) in THF261. Methylation, silylation and thiomethylation of the lithiocyclopropene intermediate afforded the corresponding 2-substituted cyclopropenes (equation 191). 

FIGURE 8. ORTEP drawing of l,2-dicHoro-l,2,3,3-tetrakis[di-tert-butyl(methyl)silyl]-l,2-disila-germirane 27... 

Jolly, W. L. The Symmetrical Deformation Frequencies of Methyl, Silyl, and Germyl Groups. J. Amer. chem. Soc. 85, 3083—3085 (1963). 

Cl-CH2-Si(OC2Hs)2-CH3 110-155 15 (Diethoxy-methyl-silyl)-methyl]- phenyl-phosphinsdure-ethylester 90 126-129 1,5 (0,2) 540... 

Dimethylamino-phenyl)-phcnyl- XII/1, 238 Dimethyl- -Anhydrid E2, 175, 176 Dimethyl- -anilid XII/1, 263 Dimethyl- -azid E2, 244 Dimethyl- -benzimidazolid E2, 232 Dimethyl- -2-benzimidazolylamid E2, 231 Dimethyl- -benzylamid E2, 164 Dimethyl- -(2-chlor-ethylester) XII/1, 249 Dimethyl- -chlorid XII/1,162, 242, 245, 249 E2, 139, 160, 163, 176, 231, 232, 234 aus Dimethylphosphinigsaure und Chlor E2, 160 aus Dimethylphosphinsaurc und Phosgen E2, 162, 164 Phosphor(V)-chlorid XII/1, 241 aus Dimethyl-thiophosphinsiiure-chlorid und Sulfurylchlorid XII/1, 244 Dimethyl- -[(diethoxy-methyl-silyl]-methvlester] aus Chlormethyl-diethoxy-methyl-silan und Natrium-dimethylphosphinat E2, 213 Dimethyl- -(dimethylaluminylester)-methylimid E2, 293... 

Diethoxymethan- -diethylester E2, 347, 364 2-(Dicthoxy-methyl-silyl)-ethan- -dimethylester XII/1, 467... 

Lithium tetrakis[methyltelluro]aluminate, prepared from methanetellurol and lithium aluminum hydride, reacted with silyl, germyl, and stannyl halides at low temperatures to produce, for instance, methyl silyl tellurium derivatives1. 

Silyl iodide and bromide reacted with methyl and phenyl trimethylsilyl tellurium only upon heating at 60° for at least five hours. Phenyl silyl tellurium and methyl silyl tellurium were obtained in 78% and 90% yield, respectively. 

However, methyl silyl tellurium decomposed forming silane and silylene bis[methyltellur-ium]1. 

Sharp, J. H., Symons, M. C. R. Unstable intermediates. Part LXXXI. Electron spin resonance spectra of 7-irradiated methyl silanes Methyl silyl radicals. J. Chem. Soc. 

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