Allylsilylation of alkenes catalyzed by H+-exchanged montmorillonite with water

•Proton-exchanged montmorillonite showed catalytic activity for allylsilylation of alkenes.•A wide variety of alkenes were converted to the corresponding allylsilylated products.•The increasing of the amount of water drastically accelerated the allylsilylation of alkenes.

Proton-exchanged montmorillonite (H+-montmorillonite) was found to be a heterogeneous catalyst for allylsilylation of alkenes with allylsilanes. A wide variety of aromatic and aliphatic alkenes were effectively converted to the corresponding allylsilylated products in 15–120 min at 60–100 °C using H+-montmorillonite with ca. 1-2 wt% of water. The increasing of the amount of water drastically accelerated the allylsilylation of alkenes. For example, the reaction of p-chlorostyrene with allyltrimethysilane afforded 90% yield of the product for 15 min at 40 °C using H+-montmorillonite with 8.8 wt% of water, whereas only 2% yield of the product was obtained with 1.3 wt% of water. However, the final product yields with H+-montmorillonite with 1–2 wt% of water were higher than that with the 8.8 wt% of water. A reaction mechanism including the formation of a disilylpropyl cation was proposed. One possible explanation for the role of water is stabilization of the active disilylcation on the montmorillonite surface and/or edges via electron donation from water molecules.

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