Tertiary Amine-Derived Ionic Liquid-Supported Squaramide as a Recyclable Organocatalyst for Noncovalent On Water Catalysis

Chiral tertiary amine-derived ionic liquid supported squaramide was synthesized from available precursors and applied as an efficient organocatalyst for asymmetric Michael additions of beta-dicarbonyl compounds to alpha-nitroolefins in the presence of water. Corresponding Michael adducts were generated under proposed conditions in nearly quantitative yield with high enantioselectivity (up to 99% ee). Useful precursors to pharmaceutically important chiral beta-amino acids and anticonvulsant Pregabalin were conveniently prepared using the developed on water protocol. The catalyst is readily recoverable and reusable over 30 times without a significant decrease of catalytic reaction activity and selectivity.