Chemistry of ammonium betaines: Application to ionpair catalysis for selective organic transformations

Abstract

The ammonium betaine was developed as an intramolecular ionpair catalyst for realizing cooperative catalysis of a cation and anion; i.e. ionpair catalysis. Combination of the stereocontrolling ability of the chiral ammonium ion and functions of the pairing aryloxylate ion enabled bifunctional organic base catalysis and ionic nucleophilic catalysis, which facilitate a variety of organic transformations with rigorous stereochemical control. In addition, employing a singleelectronaccepting cation as a partner of the basic aryloxylate led to the development of a chemical redox catalyst with the capability of protoncoupled electron transfer (PCET). This research demonstrates a power of the ionpair catalysis in selective organic synthesis and is therefore likely to stimulate further study in this field.