Alkenes iodomethyl trimethylsilane

A major detraction to the p-silyl sulfone route to alkenes is its narrow scope, owing to the paucity of methods for preparing the requisite p-silyl sulfones. The method has so far been largely restricted to monosubstituted and 1,1-disubstituted ethylene derivatives because the P-silyl sulfones have usually been most conveniently and economically prepared by the alkylation of a sulfone anion with iodomethyl-trimethylsilane. Unfortunately higher haloalkylsilanes are difficult to prepare and their alkylation chemistry remains unexplored. 

Alternative Routes to Substituted (2-Phenylsulfonylethyl)-trimethylsilanes. Although the fluoride-induced elimination is a reliable and efficient method for synthesizing alkenes, the requisite silyl sulfone precursors are often better prepared by methods which avoid the use of (2). For example, eq 3 illustrates an alternative synthesis of 2,2-dialkyl-2-(phenylsulfonylethyl)trimethyl-silanes involving alkylation of a lithio sulfone with (iodomethyl)-trimethylsilane. ... 

A cold ( — 78°) soln. of LDA in THF added dropwise to a cold soln. of startg. imine in the same solvent, after stirring for 3-6 h (2-iodomethyl-2-propenyl)trimethylsilane added, the mixture allowed to warm to room temp, over ca. 3 h, stirred at room temp, for 12 h, treated with Lil, and stirring continued at 40° for 12 h - product. Y 75 /o. Ester groups and alkenes remained unaffected. F.e. and oxidation to pyridines with Hg(OAc)2 in AcOH s. T.W. Bell, L.-Y. Hu, Tetrahedron Letters 29, 4819-22 (1988). 

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