Catalytic asymmetric Henry reaction using copper(II) chiral tridentate Schiff-base complexes and their polymer-supported complexes

A series of chiral tridentate Schiff-base ligands and their polymer-supported ligands were conveniently prepared and introduced as copper(II) chiral complexes for the asymmetric Henry reaction. The structures of these ligands have been characterized by IR, ¹H NMR, ¹³C NMR and MS. The experimental results showed that the corresponding β-nitro alcohols were obtained in moderate to high yields (up to 98%) with up to 98% ee under mild conditions. The complex catalyst forming from copper(II) polymer-supported ligands could be recycled by a simple filtration and reused 6 times at least with similar good catalytic effect (about 94% yield and 90% ee).