Preparation of Functionalized Branched Lithiosilanes and their Application in Sila-olefination

Alexander Kaushansky, Chemistry, Technion, Haifa, Israel
Shimon Maximenko, Chemistry, Technion, Haifa, Israel
Mark Botoshansky, Chemistry, Technion, Haifa, Israel
Dmitry Bravo-Zhivotovskii, Chemistry, Technion, Haifa, Israel
Yitzhak Apeloig, Chemistry, Technion, Haifa, Israel

We report the preparation of new disilyl-substituted lithiosilanes, (R₃Si)₂SiXLi (2) carrying several functional groups X = F, H, Me₂N, OLi, using a lithium-bromine exchange reaction.

A silicon modification of the Peterson-olefination reaction (sila-olefination) was previously successfully applied to the synthesis of silenes (R₂C=SiR₂) by using a tris(silyl) lithiosilane, i.e., 2, X = R₃Si. Attempts to prepare silenes with substituents X other than R₃Si were not successful. We now report the first successful generation of a substituted silene 3a, X=H, by this reaction using (t-Bu₂MeSi)₂HSiLi (X = H). 3a dimerizes to 4a which was isolated. Preparation of other functionalized silenes 2b-d and the corresponding silenes and disilacyclobutanes using functionalized lithiosilanes will be attempted in the near future.