1,5-Hydride Shift in the Aluminum Chloride Promoted Allylsilylation of 5-Silyl-1-alkenes

Linear 4-alkyl-5-silyl-1-alkenes 1a − c react with allylsilanes 2a,b in the presence of aluminum chloride catalyst at 40 °C to give unusual allylsilylation products 3a − d derived from an intramolecular silyl group rearrangement in 23−57% yield. The reaction of cyclic 1-allyl-2-(trimethylsilyl)cycloalkanes 1d, e with 2 gave the silyl-rearranged isomers of 1 in addition to the allylsilylation products 3e, f . The results are consistent with silylenium ion formation and a 1,5-hydride shift in the allylsilylation and isomerization.