Abstract
This Account summarizes the fascinating chemistry of cyclopropyl-stabilized silylium
ions, which are readily available from vinylcyclopropanes (VCPs). Depending on the
nucleophilic partner, these reactive intermediates undergo direct ring opening or
ring expansion to nonclassical alkene-stabilized silylium ions. The latter can also
be accessed by gold as well as proton electrophiles from silicon compounds containing
unsaturated C–C bonds. All these reaction cascades can be terminated by C–H or C–C
as well as Si–O bond formation. From this, a clearer picture of the versatility of
these rather complex chemistries emerges.
1 Introduction
2 Skeletal Rearrangements of Vinylcyclopropanes Involving Cyclopropyl-Stabilized
Silylium Ions
2.1 Termination by C–H Bond Formation
2.2 Termination by C–C Bond Formation
3 Related Bond Reorganizations Involving Alkene-Stabilized Silylium Ions
3.1 Initiation by Cationic Gold(I) Complexes
3.2 Initiation by Brønsted Acids
4 Conclusion
Keywords
β-silicon effect - bond reorganization - carbenium ions - ring expansion - silylium
ions - skeletal rearrangements - vinylcyclopropanes