Stereoselective Synthesis of Optically Pure NOBINs by Oxidative Coupling between Aminonaphthalenes and 2-Naphthols

2-amino-2-hydroxy-1,1’-binaphthyl (NOBIN) compounds are important class of structural motif with axial chirality that are used as ligands and catalysts in asymmetric transformations. The preparation of optically pure NOBINs mainly relies on resolution or multistep synthesis starting from optically pure BINOLs. As part of our group’s on-going research, we have developed a novel method for efficient synthesis of chiral NOBIN frameworks by direct oxidative coupling between naphthylamines incorporated with a chiral auxiliary and 2-naphthols.

The resulted NOBIN diastereoisomers are separated over column chromatography and the chiral auxiliary can be easily removed to furnish each of the NOBIN enantiomers in gram scale.