Metal complexes of chiral binaphthyl Schiff-base ligands and their application in stereoselective organic transformations

Abstract

Condensations of aromatic aldehydes with 2,2′-diamino-1,1′-binaphthyl or 2-amino-2′-hydroxy-1,1′-binaphthyl afford various chiral binaphthyl Schiff-base ligands, the most common of which are potentially tetradentate with a N 2O 2 donor set. The chiral binaphthyl Schiff-base ligands have been shown to form stable complexes with metal ions of Al(III), Ti(IV), Cr(III), Mn(II)/Mn(III), Fe(II)/Fe(III), Co(II)/Co(III), Ni(II), Cu(II), Zn(II), Y(III), Zr(IV), Ru(II), and Pd(II); some of such complexes have been characterized by X-ray crystallography. Catalytic studies reveal that these types of chiral metal complexes are active catalysts for stereoselective organic transformations including hydroxylation of styrene, aldol reactions, alkene epoxidation, trimethylsilylcyanation of aldehydes, desymmetrization of meso- N-sulfonylaziridine, Baeyer-Villiger oxidation of aryl cyclobutanone, Diels-Alder reactions of 1,2-dihydropyridine, and ring-opening polymerization of lactide.