A simple method for chiral resolution of 1,1′-Bl-2-naphthol

An improved method for preparing enantiomerically pure 1,1′-bi-2-naphthols is described. 1,1′-bi-2-naphthol boric anhydride was generated from the reaction of racemic 1,1′-bi-2-naphthol and boric anhydride. Its two diastereoisomers, could be efficiently separated in THF using (L)-proline as the resolving agent. Treatment in three successive steps yielded 79% and 74% enantiomerically pure (S)-and (R)-1,1′-bi-2-naphthol respectively.