Insertion, Isomerization, and Cycloaddition Reactions of Lithiated Aminofluorosilanes
The lithium derivative 2 of (di-tert-butylfluorosilyl)(fluorodiisopropylsilyl)amine (1) reacts with benzoyl chloride to form the imines 3I and 3II in an insertion reaction.LiF elimination from 2 leads to the cyclodisilazane2 (4).The fluorine atom of the SiF(CHMe2) group in 1 can be substituted by means of LiOSiMe3 to yield 5.The lithium derivative of 5 (6) is a dimer with very short Li-F distances.The lithium derivative 6 reacts with benzaldehyde in a cycloaddition to give an SiNCO) four-membered ring compound (7), which thermally decomposes to yield the imine 8 and a cyclosiloxane.A fluorine/chlorine exchange is observed when Me3SiCl is added to the lithium derivative 6.The resulting unstable lithium derivative of an aminochlorosilane eliminates LiCl to form the cyclodisilazane 9.According to a crystal structure determination the formation of 9 involves isomerization of the intermediate iminosilane followed by dimerization. Key Words: Silanes, aminofluoro- / Insertion /Isomerization / Cycloaddition
Additionen an die Si=N-Doppelbindung - Kristallstruktur eines (SiNCO)-Vierringes
In the reaction with benzophenone and phenylaldehyde lithiated aminofluorosilanes behave like iminosilanes.Four membered rings are formed in (2+2) cycloadditions.The oxaazasilacyclobutane ((CMe3)2Si-NCMe3-C6H5CH-O-) was purified by destillation.Single cry