Enantioselective nitroaldol (Henry) reaction catalyzed by chiral Schiff-base ligands

Chiral Schiff-bases 2, 3, 4 and 5 were designed for the enantioselective nitroaldol (Henry) reaction. The highest enantioselectivity was observed for ligand 4 (82% ee) when CH2Cl2 was used as a solvent.