ORGN 683 |
| Enantiomeric discrimination is observed in the H-1 and C-13 NMR spectra of chiral secondary amines in the presence of optically pure (18-crown-6)-2,3,11,12-tetracarboxylic acid. Secondary amines are protonated by one of the carboxylic acid groups of the crown ether to produce the corresponding ammonium and carboxylate ions. The secondary ammonium ion likely forms two hydrogen bonds to crown ether oxygen atoms and an ion pair with the carboxylate anion. Enantiomeric discrimination is observed in the spectra of a wide variety of secondary piperidines, piperazines, pyrrolidines, and alkyl aryl amines. Preliminary studies also indicate that the H-1 and C-13 NMR spectra of chiral tertiary amines show enantiomeric discrimination in the presence of optically pure (18-crown-6)-2,3,11,12-tetracarboxylic acid, although it is usually less significant than that observed in the spectra of secondary amines. |
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Asymmetric Reactions, Combinatorial Chemistry, Molecular Recognition and Self-Assembly, Proteins, Peptides, Amino Acids and Enzyme Inhibitors
8:00 PM-10:00 PM, Wednesday, March 28, 2007 Hyatt Regency Chicago -- Riverside Center, Poster
Division of Organic Chemistry |