Enantioselective Oxidation of Alkenes with Potassium Permanganate Catalyzed by Chiral Dicationic Bisguanidinium

Chiral
anion-controlled ion-pairing catalysis was demonstrated
to be a wide-ranging strategy that can utilize a variety of cationic
metal species. In a similar manner, we envision a complementary strategy
using chiral cation in partnership with inorganic anionic metal salts.
Herein, we report a chiral dicationic bisguanidinium-catalyzed asymmetric
oxidation reaction of alkenes with potassium permanganate. Chiral
induction is attributed to ion-pairing interaction between chiral
cation and enolate anion. The success of the current permanganate
oxidation reaction together with mechanistic insights should provide
inspiration for expansion to other anionic metal salts and would open
up new paradigms for asymmetric transition metal catalysis, phase-transfer
catalysis, and ion-pairing catalysis.