Development of Synthetic Methods for the Silaallene Cationic Species and the Related Compounds and Their Application Reactions

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First, we have developed highly efficient synthetic methods for diarylmonoalkynylfluorosilanes and dialkynyldiarylsilanes as follows. Reaction of aryllithiums with tetrachlorosilane gave monoaryltrichlorosilanes, which were treated with other aryllithiums to afford diaryldichlorosilanes. After halogen exchange reaction (Cl→F), treatment of the resulting diaryldifluorosilanes with alkynyllithiums gave the desired diarylmonoalkynylfluorosilanes. Their similar reactions with other alkynyllithiums furnished the corresponding alkynyl-substituted dialkynyldiarylsilanes in excellent yields. Treatment of the monoalkynylmonoarylfluorosilane bearing t-Bu, Tip, phenylalkynyl, and fluorine atom with t-BuLi at 0℃ and then at room temperature or under reflux generated a 1-silaallene. The 1-silaallene was in situ allowed to react with ketones, aldehydes, and an imine to give the corresponding 1,2-oxasiletanes and 1,2-azasiletane, respectively. Treatment of the differrent kinds of alkynyl-substituted dialkynyldiarylsilanes with biscyclopentadienylzirconocene-ethylene complex followed by acidification with 3N HC1 gave regio-and stereoselectively the corresponding silacyclobutenes in good yields. Desilylation of the silacyclobutenes with tetrabutylammonium fluoride afforded stereoselectively unsymmetrical conjugated dienes and trienes in excellent yields, respectively.