Aluminum Chloride-Catalyzed Intramolecular Allyl-Migration Reaction of Allyl(chloromethyl)silanes and Trapping of the Intermediate with Allyltrimethylsilane

Allyl(chloromethyl)diorganosilanes [CH2CHCH2SiR1R2(CH2Cl), R1 = Me, Ph; R2 = Me, Ph, p-ClC6H4] in the presence of aluminum chloride undergo an allyl rearrangement reaction with allylic inversion to afford (3-butenyl)diorganochlorosilanes at room temperature. When allyltrimethylsilane was added to the reactions, the intermediate was trapped to give 1,1-dimethyl-3-(2-trimethylsilylmethyl-4-pentenyl)silacyclopentane (4) along with 3-(butenyl)dimethylchlorosilane in 40% and 18% yields, respectively. The formation of 4 can be explained by the addition reaction of allyltrimethylsilane to 1-silacyclopent-3-yl cation produced by the intramolecular cyclization of (allyl)silylmethyl cation intermediate derived from the interaction of the chloromethyl group with aluminum chloride catalyst, followed by desilylation reaction.