Performance-Enhancing Asymmetric Catalysis Driven by Achiral Counterion Design.

The development of highly enantioselective reactions often requires the adventitious discovery of a promising chiral catalyst and its resource-intensive optimization to high selectivity and generality. We report an approach less dependent on happenstance, whereby the performance of a single chiral ligand is enhanced not by modification of the architecturally complex chiral features but instead by an achiral counteranion. Critical to this strategy and its general application is the tactical development of -aryl trifluoromethyl sulfonamide Brønsted acid donors and their ability to unlock the full enantioselectivity potential of a single chiral Brønsted basic ligand for the enantioselective addition of azide to nitroalkene.