CARB 15 |
| Septanoses are representatives of a broad class of unnatural, expanded carbohydrates characterized by having seven (rather than five or six) atoms in their ring. We became interested in what, if any, biological activity would be associated with carbohydrates that were either partially or completely made up of septanose residues. In posing questions about the potential activity of septanose carbohydrates, it was apparent that there were only limited reports on the preparation and conformation analysis of seven membered ring sugars. Here we present a comprehensive approach to the investigation of septanose carbohydrates. We have developed routes for the synthesis of a variety of septanoside structures, including a disaccharide that contains a septanose residue at both the reducing and non-reducing end of the structure. Nearly all of our synthetic efforts rely on efficient access to carbohydrate based oxepines which are essentially ring expanded glycals. We have approached the onformational analysis of some representative septanoside structures via comparison of calculated and experimental 3JH,H coupling constants. These efforts have allowed insight into the factors that govern the preference for specific low energy conformations. With access to some simple septanose structures and a knowledge of their conformational preferences, we have begun to investigate the interactions of these structures with natural proteins. For example, the jack bean lectin Concanavalin A (ConA) can bind methyl beta-septanosides. The selectivity for beta-septanosides is in contrast to the natural ligands of ConA which are alpha-pyranosides. An analysis of this interaction will be presented based in terms of the complete set of ligands that have been investigated to date. |
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Melville L. Wolfrom/Horace S. Isbell New Investigator Awards Symposium
1:00 PM-4:45 PM, Sunday, 10 September 2006 Hilton San Francisco -- Yosemite C, Oral
Division of Carbohydrate Chemistry |