Conjugate Addition of 1,3-Dicarbonyl Compounds to Maleimides Using a Chiral C2-Symmetric Bis(2-aminobenzimidazole) as Recyclable Organocatalyst

The recyclable chiral 2-aminobenzimidazole-derived organocatalyst 1f efficiently promotes the room temperature asymmetric conjugate addition of 1,3-diketones, β-ketoesters, and malonates to maleimide and N-substituted maleimides, affording the corresponding Michael adducts in excellent yields and enantioselectivities even at gram scale.