SYNTHESIS OF 3,3'-SUBSTITUTED, 6,6'-SUBSTITUTED AND 3,3',6,6'-SUBSTITUTED BINAPHTHOLS AND THEIR APPLICATION IN THE ASYMMETRIC HYDROPHOSPHONYLATION OF ALDEHYDES - AN OBVIOUS EFFECT OF SUBSTITUENTS OF BINOL ON THE ENANTIOSELECTIVITY

By using a direct ortho-lithiation strategy and/or Ni-catalysed coupli ng reaction, we have conveniently synthesized three new chiral polysub stituted BINOLs of vast synthetic potential from (S)-BINOL 1 in reason able yields, Moreover, we have examined closely their influence on the enantioselectivity of the asymmetric Pudovik reaction catalyzed by ch iral binaphthol-modified lanthanum alkoxides, The results show that th e steric bulk of 3,3'-substituents of BINOL is responsible for a lower ing of the enantioselectivity of the reaction, while coordination betw een the oxygens of the ortho-substituents and the lanthanum ion is ben eficial in improving the asymmetric induction. 6,6'-Diphenyl-BINOL has the advantage over simple BINOL in giving the best asymmetric results -Further studies on this aspect are in progress.