stable allenyl, propargyl, or allyl-propargyl hybrid cations have been developed. These carbocations could be generated from silyl 1-(pi-donor)-substituted propargylethers by the action of trimethylsilyl trifluoromethanesulfonate in dichloromethane at -78 degrees C to room temperature and could be attacked nucleophilically by electron rich arenes, allylsilanes, or enol silyl ethers, giving rise to