Asymmetric electrophilic fluorination using an anionic chiral phase-transfer catalyst

Abstract

The discovery of distinct modes of asymmetric catalysis has the potential to rapidly advance chemists' ability to build enantioenriched molecules. As an example, the use of chiral cation salts as phase-transfer catalysts for anionic reagents has enabled a vast set of enantioselective transformations. A largely overlooked analogous mechanism wherein a chiral anionic catalyst brings a cationic species into solution is itself a powerful method. The concept is broadly applicable to a number of different reaction pathways, including to the enantioselective fluorocyclization of olefins, and dearomatization of aromatic systems with a cationic electrophile-transferring (e.g., fluorinating) agent and a chiral phosphate catalyst. The reactions proceed in high yield and stereoselectivity. The compounds and methods of the invention are of particular value, especially considering the scarcity of alternative approaches.