CARBANIONEN-UMLAGERUNGEN DURCH INTRAMOLEKULARE 1,ω-PROTONVERSCHIEBUNG. II. ZUR REAKTIONSWEISE VON 3-, 4- UND 5-LITHIOALKYL-TRIMETHYLSILANEN

Article abstract of DOI:10.1016/S0022-328X(00)89867-8

ω-Lithioalkyltrimethylsilanes, prepared from ω-bromoalkyltrimethylsilanes and lithium metal, are fairly stable in diethyl ether as solvent.Upon addition of tetrahydrofuran, however, rearrangements take place, the modes of which are strongly dependent on the number of methylene groups between the lithium and the silicon atoms.With 3-lithiopropyltrimethylsilane an intramolecular 1,5-proton shift with the formation of lithiomethyldimethylpropylsilane is observed.With 4-lithiobutyl-trimethylsilane on the other hand, ring closure to 1,1-dimethylsilacyclopentane takesplace, whereby methyllithium is formed by intramolecular nucleophilic attack on silicon. 5-Lithiopentyltrimethylsilane finally shows ring closure as well as 1,7-proton shift, the ratio depending on the polarity of the solvent.