CARB 75 |
| Protecting groups in organic synthesis are considered as invaluable tools allowing for more regio- and chemo-selective synthesis. However, the use of protecting groups also increases considerably the number of steps in any multi-step synthesis. In carbohydrate chemistry, protection and deprotection of the many hydroxyl groups can be very difficult, tedious and wasteful both economically and atomically. We are currently developing directing-protecting groups that would allow for regio- and chemo-selective synthesis through one single protection step. In other words, one protecting group installed on the hydroxyl at position 6 of a pyranose (as shown in the scheme) would also modulate the reactivities of the other positions, thus replacing the use of multiple protecting groups. These directing-protecting groups take advantage of intramolecular hydrogen bonds which modulate the conformation and reactivity of the hydroxyl groups. Both hydrogen bond donor and acceptor groups were investigated. Among them, novel hydrogen bond acceptor protecting groups were used to induce steric hindrance around the free hydroxyl groups at positions 3 and 4, while also increasing the relative nucleophilicity at position 2. The results of these and others will be discussed.
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General Posters
6:00 PM-8:00 PM, Tuesday, August 21, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Carbohydrate Chemistry |
