Highly Diastereo- and Enantioselective Michael Addition of Nitroalkanes to 2-Enoyl-Pyridine N-Oxides Catalyzed by Scandium(III)/Copper(II) Complexes.

Abstract

A C2 -symmetric Schiff-base ligand, derived from tridentate-Schiff-base, was developed and successfully applied to the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides. With this newly catalytic system, an unprecedented diastereoselectivity was obtained in the asymmetric Michael addition of nitroalkanes to 2-enoyl-pyridine N-oxides. In addition, a switch in enantioselectivity was achieved by using this newly catalytic system and our previous catalyst. After a facile reduction, the optically active adduct was converted to a biologically active dihydro-2H-pyrrol 4 a. Furthermore, a connection of two tridentate-Schiff-base subunits proved to be an effective strategy in ligand design.