Transition Metal Catalyzed Aerobic Asymmetric Coupling of 2-Naphthols

Optically pure 1,1'-bi-2-naphthol (BINOL) and its derivatives are among the most widely used chiral ligands and auxiliaries for asymmetric synthesis. These molecules also occur as scaffolds for various biologically active compounds. Direct oxidative coupling of 2-naphthols in the presence of chiral catalysts provides a powerful strategy for the synthesis of optically pure 1,1'-bi-2-naphthols (BINOLS). In 1978, Wynberg with co-workers discovered that a copper salt with chiral auxiliary mediates the oxidative coupling of 2-naphthols, which can be taken as the starting point for further progress in this area. Over the last decades, a number of efficient and stereoselective catalyst systems have been developed. This mini-review surveys the aerobic asymmetric oxidative coupling of 2-naphthols catalyzed by transition metal complexes reported since 1995.