The Electrophilic Substitution of Allylsilanes and Vinylsilanes

Allylsilanes and vinylsilanes usually react with electrophiles to give substitution. These reactions are conveniently understood as the reactions of alkenes that have been significantly but only slightly modified by the presence of the silyl group. In both reactions, substitution is favored over addition, and both the site of attack and the site of the double bond in the product are usually determined by the site of the silyl group in the starting material. In this chapter only the electrophilic substitution reactions of allylsilanes, vinylsilanes, and allenylsilanes is discussed. It is further restricted to the reactions of tetraorganosilanes because they are synthetically the most interesting in the laboratory. However, although they are not included in the tables, allylsilanes and vinylsilanes that react by addition rather than substitution or that are not tetraorganosilanes are referred to occasionally in the text wherever their reactions illuminate the discussion. Many of the features of the reactions discussed here are shared by the reactions of arylsilanes, ethynylsilanes, propargylsilanes, cyclopropylsilanes, and cyclopropylmethylsilanes. The methods by which allylsilanes and vinylsilanes are synthesized have been summarized in several places. Stereochemsitry of reactions of allenylsilanes and vinylsilanes is discussed. Scope and limitations include discussions of protodesilylation and deuterodesilyation and the use of carbon, nitrogen, and oxygen as electrophiles. Other electrophiles include phosphorus, sulfur, metals, halogens, and selenium. All of these are covered in the extensive tabular material Keywords: electrophilic substitution; allyl silanes; vinylsilanes; mechanism; stereochemistry; reactivity; regioselectivity; scope; limitation; protodesilylation; deuterodesilylation; allenyl silanes; carbon electrophiles; catalysts; nitrogen electrophiles; oxygen electrophiles; phosphorus electrophiles; sulfur electrophiles; aldehydes; alkyl halides; alcohols; ethers; nitro compounds; epoxides; carbonyls; alkanes; quinones; acid chlorides; acid anhydrides; acetals; experimental procedures