Macrocycle binaphthyl-derived

Naruta et al. [225, 226] designed the twin-coronet porphyrin ligands (62) and (63) with binaphthyl derivatives as chiral substituents (Figure 13). Each face of the macrocycle is occupied by two binaphthyl units and the ligand has C2 symmetry. Iron complexes of these compounds can be very effective catalysts in the epoxidation of electron-deficient alkenes. Thus, nitro-substituted styrenes are readily epoxidized in 76-96% ee [226]. The degree of enantioselectivity can be explained on the basis of electronic interactions between the substrate aromatic ring and the chiral substituents rather than on the basis of steric interactions. 

Pu and coworkers have synthesized and studied numerous binaphthyl-derived macrocycles and polymers. In 1998, they reported the synthesis of multipolar macrocycles 161-163 [58]. The macrocycles were produced as a separable mixture via a one-pot synthesis utilizing a Sonogashira cross-coupling reaction. 

For the lanthanide Ce(III), Eu(III), La(III) complexes being derivatives of R-2,2 -diamino-l,l -binaphthyl and 2,6-diformylpyridine, the formation of the macrocycle of D2 symmetry was suggested.113 The full assignment... 

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. 

For enhancement of fluorescence, molecules with intramolecular fluorescence quenching of photoinduced electron transfer (PET) of lone pairs are used. When interacting with the target molecule, this quenching will be inhibited and therefore the fluorescence can be turned on. The l,T-binaphthyl macrocycles are most extensively applied for this method they provide multiple chiral functional groups as binding sites for analytes such as a-hydroxycarboxylic acids, amines and even amino acid derivatives [5] (Fig. 3, left). 

Li ZB, Lin J, Pu L (2005) A cyclohexyl-1,2-diamine-derived bis(binaphthyl) macrocycle enhanced sensitivity and enantioselectivity in the fiuorescent recognition of mandelic acid. Angew Chem Int Ed 44 1690-1693... 

In efforts to generate receptors for the enantioselective complexation of naproxen derivatives, e.g. 12a/b, in aqueous solution, we prepared a series of optically active, water-soluble cyclophanes (13 -17) with tqx>lar cavities shtqied by the major giwves of the 2,2 ,6,6 - and 2,2 ,7,7 -tetraoxa-l,r-binaphthyl units [30,31]. The synthesis of macrocycle 15 is shown in Scheme 6. 

Chiral crown ethers are synthetic macrocyclic polyethers and were first introduced as CSPs for LC by Cram and co-workers in the late 1970s. In their pioneer works, bis-(l,r-binaphthyl)-22-crown-6 was immobilized on silica gel [126] or polystyrene [127] to resolve a-amino acids and their derivatives. Since then, different chiral crown ether CSPs have been developed and successfully applied in the HPLC separation of enantiomers containing primary amine and secondary amine groups [20, 128-139]. Both dynamically coated [128, 129] and covalently bonded [130-132] chiral crown ether CSPs are commercially available. 

---