ORGN 679 |
| Development of bis-tri-phenylporphyrin tweezer and its application as a host molecule has provided a way to determine the absolute stereochemistry of small molecules by means of exciton-coupled circular dichroism (ECCD). Recent work in this area has included stereochemical determination of 2-chiral carboxylic acids. We have synthesized bulky porphyrin tweezers in order to study the influence of additional steric interactions on the sign and amplitude of the ECCD couplet. As a result of these studies we are able to achieve significant increase in the amplitude of the observed bisignates as compared to the previously used ZnTPP-porphyrin tweezer for all tested diamines and a-chiral alkyl, aryl and alkoxy carboxylic acids. Additionally some interesting changes in ECCD active conformation of tested 2-chiral halo carboxylic acids were observed and studied. The results indicate that increasing the steric demand of the porphyrin significantly improved sensitivity of the modified porphyrin tweezers towards the size of the substituents at the asymmetric center. Results for stereochemical determination of 3- and 4-chiral alkyl, aryl, hydroxy and halo-carboxylic acids will be discussed.
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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 |
