Unique asymmetric catalysis of cis-β metal complexes of salen and its related Schiff-base ligands

Abstract

Complexes of chiral salen and its related tetradentate Schiff-base ligands adopt three different configurations, trans, cis-α and cis-β. Of these complexes, trans-complexes have been widely used as catalysts for various asymmetric reactions. However, recent studies have disclosed that cis-β metallosalen and its related complexes show unique asymmetric catalyses that cannot be achieved by trans-metallosalen complexes. The present article summarizes generation of cis-β metallosalen and its related complexes, their structural features, and their application to asymmetric syntheses.