Self-assembled proline-amino thioureas as efficient organocatalysts for the asymmetric Michael addition of aldehydes to nitroolefins

A small co-catalyst library of amino thioureas has been established from chiral 1,3-diamines. These bifunctional thioureas can form assemblies with proline to cooperatively catalyze the asymmetric Michael addition of aldehydes to nitroolefins. Both the reaction rate (up to 98% yield for 18 h) and the enantioselectivity (up to 94% ee) were significantly improved upon in less polar solvents.