The chemoselective allylation of acetals using allyltrimethylsilane in ionic liquids is catalyzed by TMS triflate (5.0-20.0 mol %). The reaction proceeds smoothly at room temperature to afford the corresponding homoallyl ether in good yield. Since the ionic liquids are easily recovered and recycled, they are a useful alternative to dichloromethane, which is the commonly used solvent for allylations. [reaction--see text]