In 1948, it was discovered that allyltrimethylsilane reacts with hydrobromic acid to give (2-bromopropyl)trimethylsilane. Six years later, the generation of (2-iodoethyl)trimethylsilane from vinylsilane and HI was observed. Since then, a number of studies have firmly established the mechanism of electrophilic attack on vinyl- and allylsilanes The electron-releasing strength of the carbon-silicon bond is large, and as a result, the position of silicon in the unsaturated silane controls the site of reaction and stereoselectivity. Formation of the new carbon-carbon bond is at the γ position of allyl silanes and the β position of vinylsilanes. The robustness of silanes makes them amenable to use in synthesis; however, because silicon is less electropositive than other metals employed in electrophilic additions, stronger electrophiles are required.