Binaphthols, , macrocyclic derivatives

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. 

An established area of application of macrocyclic polyethers is the stereoselective complexation of chiral guest primary alkylammonium salts by optically active host macrocycles. Full details of the resolution, optical stability, and inclusion into chiral hosts of the binaphthol (84), and also of the chiral recognition properties of crowns [e.g. (85)] based on simple carbohydrate precursors, have been reported this year. An extension of the latter work" utilizes derivatives of the more complex carbohydrates D-glucose and D-galactose. The macrobicyclic polyethers (86) derived from D-glycerol or pentaerythritol have been suggested as potential chiral (at the bridgeheads) cryptands. 

The chiral macrocyclic polyether (U)-d-(521) and its (5)-D-diastereoisomer have been derived from D-mannitol and (R)- or (S )-binaphthol, respectively. Significant changes were observed in the n.m.r. spectra of (/ )-d-(521) and its diastereoisomer in the presence of primary alkylammonium salts [e.g. (+)-(2 )-, (-)-(5 )- and ( )-(i 5 )-a-phenylethylammonium hexafluorophos-phate], indicating that both diastereoisomers act as hosts to suitable guest molecules. The chiral hosts dd-(523) and dd-(524) have been obtained from l,2 5,6-di-0-isopropylidene-D-mannitol by the routes outlined in Scheme 100. The temperature dependence of the H n.m.r. spectrum of the 1 1 complex of dd-(524) and benzylammonium thiocyanate in [ Ha]dichloromethane was interpreted... 

---