Enantiomers phosphate anions

Our template synthesis of knots implies that the target molecules are obtained as cationic dicopper(I) complexes. Therefore we considered the possibility of interconverting both enantiomers into a pair of diastereomeric salts [137, 138] by combining them with an optically active anion. Binaphthyl phosphate (BNP") [139] drew our attention because its chirality arises from the binaphthyl core, which is twisted. This helical structure is of the same type as that of die copper double helix, precursor of the knot. Besides, both compounds are aromatic and, thus, we could expect some potentially helpful stacking interactions [87],... 

Kano has studied extensively the recognition of anions and zwitterions by both native and derivatized cyclodextrins [ 16]. The native (3-cyclodextrin com-plexation properties were examined with respect to binaphthyl derivatives. For both l,T-binaphthalene-2,2,-dicarboxylic acid and l,T-binaphthalene-2,2 -diol phosphate almost no chiral recognition was observed. The enantiomers of binaphthyl-2,2 -dicarboxylic acid were better distinguished using a per-O-methylated (3-cyclodextrin derivative in place of the native (3-cyclodextrin. 

Figure 18.16 Comparison of experimental and calculated production rate. Preparation of 99% pure enantiomers of N-benzoyl-D,L-alanine from the racemic mixture. Experimental (symbols) and calculated (solid lines) band profiles for the optimum sample size for maximum production rate at v = 13.6 of (a) the L-isomer (sample size, 43 g), and (b) the D-isomer (sample size 30 fig). BSA immobilized on a quaternary ammonium anion-exchange resin, mobile phase, 50 mM phosphate buffer with 1% acetonitrile. Reproduced with permission from S. Jacobson, A. Felinger and G. Guiochon, Biotechnol. Progr., 8 (1992) 533 (Figs. 4 and 5). (c)1992, American Chemical Society.

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