作者:Julia A. Gavin、Maurie E. Garcia、Alan J. Benesi、Thomas E. Mallouk
DOI:10.1021/jo980352c
日期:1998.10.1
A cationic chiral cyclophane was synthesized and studied as a host for chiral and racemic pi-donor molecules. The cyclophane host has a rigid binding cavity flanked by (S)-(valine-leucine-alanine) and N,N'-dibenzyl-4,4'-bipyridinium subunits, which allow for hydrogen-bonding and pi-stacking interactions with included aromatic guest molecules. H-1 NMR binding titrations were performed with several different pharmaceutically interesting guest molecules including beta-blockers, NSAIDs, and amino acids and amino acid derivatives. The host-guest complexation constants were generally small for neutral and cationic guests (0-39 M-1 at 20 degrees C in water/acetone mixtures). However, a (R)/(S) enantioselectivity ratio of 13 +/- 5 was found for DOPA, a strongly, pi-donating cationic guest. Two-dimensional NOESY H-1 NMR spectra confirm that (R)-DOPA binds inside the cavity of the host and that there is no measurable interaction of the cavity with (S)-DOPA under the same conditions.