Catalytic asymmetric coupling of 2-naphthols by chiral tridentate oxovanadium (IV) complexes.
A series of chiral oxovanadium(IV) complexes derived from tridentate N-3,5-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 CCl(4), leading to BINOLs in good yields (75-100%) and with enantioselectivities of up to 68%.
Hon
S W
SW
Department of Chemistry, National Taiwan Normal University, and Instrumentation Center, College of Science, National Taiwan University, Taipei, Taiwan, R.O.C.
Li
C H
CH
Kuo
J H
JH
Barhate
N B
NB
Liu
Y H
YH
Wang
Y
Y
Chen
C T
CT