1-(Trimethylsilyl)alk-2-enylpotassium species are readily generated by deprotonation of (alk-2-enyl)trimethylsilanes with the superbasic mixt. of BuLi and KOCMe3. Like the parent compd., [1-(trimethylsilyl)allyl]potassium, they react with a variety of electrophiles preferentially, if not exclusively, at the silyl-distant terminus of the allyl moiety, thus producing branched ene silanes. The opposite regioselectivity previously obsd. with MeI hence appears to be an exception. [on SciFinder (R)]