A Nickel-Bisdiamine Porous Organic Polymer as Heterogeneous Chiral Catalyst for Asymmetric Michael Addition to Aliphatic Nitroalkenes

We report a polystyrene-incorporated chiral nickel(II)-bisdiamine complex, which is accessible on gram-scale. This metal complex functions as a heterogeneous catalyst for the enantioselective Michael addition between malonates and aliphatic nitroalkenes, and it provides yields and enantioselectivities on par with homogeneous catalysts. Good functional group tolerance is reported for this reaction. Upon recycling, the catalyst achieves significantly higher TONs than previously reported. We demonstrate scalability to multigram-scale, compatibility with continuous flow production (4.43 gram), and application to the synthesis of the blockbuster drug Pregabalin. Finally, a new tandem reaction is disclosed.