Use of carbocations in stereoselective synthesis

Carbocation-mediated substitution commonly loses stereochemical information and competes with elimination or rearrangement. This seminar describes a strategy using nonclassical carbocations to make SN1 transformations predictable, selecting either inversion or retention. It addresses acyclic products with adjacent stereocentres and controlled regio-, diastereo- and enantioselectivity, then shows how carbon–carbon bond rearrangements can install stereodefined bonds away from the initial cation while tolerating sensitive functional groups.