Fluorosilyl(Pyrrolyl)Silylamines As Precursors for Intra- and Intermolecularly Stabilized Iminosilanes

Three indolyl- and pyrrolylsilylamines1–3 were prepared from lithiated heterocyclics and fluorosilylamines. Further reaction with di-tert-butyldifluorosilane led to the fluorosilylpyrrolylsilylamines4 and5. The fluorosilylpyrrolylsilylamine6 was prepared by reaction of bis(fluorodiisopropylsilyl)amine and lithium pyrrolide. Lithiiation with n-butyllithium of4–6 solved in THF gave the iminosilane-LiF adducts7–9; in contrast, lithiation of5 in n-hexane led to the lithium fluorosilylamid10. Heating of the iminosilane-LiF adduct7 gave the bicyclic system11, an intramolecularly stabilized iminosilane. Addition of chlorotrimethylsilane to9 led to fluorine-chlorine exchange and elimination of lithium chloride. The product is the intermolecular stabilization of the intermediate iminosilane as a four-membered ring12. The X-ray structures of1, 11 and12 have been determined.