Binaphthol isomerization

The monobenzhydiyl derivative of (S)-binaphthol has played an important role, not only in the synthesis of chiral bisbinaphthyl crown ether derivatives, for example, (55)-124, containing two different bridges between the two binaphthyl units, but also in the provision of an entry into the constimtionally isomeric derivative (5S)-125. Rational stepwise syntheses of macrocyles containing three binaphthyl units have been devised and applied to the synthesis of (SSS)-126 and (RSS)-127. Cleariy, in all these procedures, the C2 symmetry of the chiral building block restricts the number of products (to one ) and defines the symmetries of the macrocycles formed. 

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