Catalytic asymmetric coupling of 2-naphthols by chiral tridentate oxovanadium(IV) complexes

[GRAPHICS] A series of chiral oxovanadium(IV) complexes derived from tridentate N3,5-substituted and N-3,4-benzo- and N-5,6-benzo-salicylidene-alpha -amino acids can serve as efficient catalysts for the enantioselective oxidative couplings of various 3-, 6-, and 7-substituted 2-naphthols under O-2 The best scenario involves the use of a vanadyl complex arising from 2-hydroxy-1-naphthaldehyde and valine (or phenylalanine) in CCl4, leading to BINOLs in good yields (75-100%) and with enantioselectivities of up to 68%.