Two New Efficent Preparations of Enantiopure 2,2'-Dihydroxy-6,6'-dimethoxy-1,1'-biphenyl

Two new useful methods for the preparation of diol 1 starting from available compounds are described. Separation of the two enantiomers entails resolution of racemic diol 1 via the corresponding diastereomeric N-methylated phosphorothioamidates. Their separation by recrystallization followed by reduction afforded diol (aS)-I and (aR)-I in 100% and 72% ee, respectively