Catalytic Asymmetric Oxidative Couplings of 2-Naphthols by Tridentate <i>N</i>-Ketopinidene-Based Vanadyl Dicarboxylates

A series of oxovanadium(IV) complexes derived from tridentate N-ketopinidene-α-amino acids were synthesized. They serve as efficient catalysts for the enantioselective oxidative couplings of various 3-, 6-, or 7-substituted 2-naphthols. The best scenario involves the use of a vanadyl complex arising from l-tert-leucine in CCl4. The asymmetric couplings of 2-naphthols can be conducted smoothly at 40−45 °C under a stream of gaseous oxygen, leading to 2,2‘-dihydroxy-1,1‘-binaphthyls in good yields (61−99%) and with enantioselectivities of up to 87%.