We are interested in finding a method that provides high yields of chiral, non-racemic, silicon compounds that can be used in organic synthesis. Recently, we have been investigating the reactions of nucleophiles with prochiral at silicon dimenthoxy-substituted silanes.We will present our results with the reactions of nucleophiles with dimenthoxyphenylvinylsilane. The starting material, dimenthoxyphenylvinylsilane was prepared from dichlorophenylvinylsilane. Dicholorophenylvinylsilane was reacted with 2 equivalents of menthoxyllithium in THF solvent to produce dimenthoxyphenylvinylsilane, which was then purified by column chromatography and isolated in a 72.6 % yield. The dimenthoxyphenylvinylsilane was used for the reactions with napthyllithium, butyllithium, methyllithium, and tert-butyllithium. These compounds were purified by column chromatography, then they were analyzed with the use of NMR, GC- Mass Spectrum, and HPLC. The yields of these reactions varied from 18.4% to 72.05%. Diastereoselectivities have been determined from 13C-NMR data, and in the case of the methyllithium substitution initial results are consistent with a high selectivity for one diasteriomer.To explain the observed selectivity we have calculated structures for the dimenthoxy substituted silanes using Gaussian 03. These calculations show that one of the menthoxy groups should be more open for nucleophilic substitution, Figure 1.                              Figure 1. View of the dimenthoxymethylphenylsilane emphasizing open space for back side attack of one menthoxy group by the nucleophile.

Synthesis of chiral vinyl-substituted silanes

247th National Meeting (2014)

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