Stereoselective glycosylations using chiral auxiliaries at C-2 of glycopyranosyl donors

CARB 39

Hai Yang, hyang@chem.uga.edu, Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602-4712, Jin Hwan Kim, Department of Chemistry, University of Georgia, Complex Carbohydrate Research Center, 315 riverbend road, athens, GA 30602, Vishal Knot, vkhot@chem.uga.edu, department of chemistry, university of georgia, athens, 30602, and Geert Jan Boons, gjboons@ccrc.uga.edu, Complex Carbohydrate Research Center, University of Georgia, Athens, 220 Riverbend Road, Athens, GA 30602.
The stereoselective introduction of glycosidic bonds presents one of the main challenges to the synthesis of complex oligosaccharide. We have developed a novel approach for controlling anomeric configurations of glycosylation using a chiral auxiliary at C-2 of a glycosyl donor. The first auxiliary that we developed was a (S)-ethoxycarbonylbenzyl ether, which is proposed to react through a trans-fused dioxolenium ion intermediate leading to the formation of mainly alfa-glycosides. Furthermore, a (1S)-(6S)-phenylsulfanyl-2-cyclohexenyl ether has been employed as an improved chiral auxiliary. NMR studies have shown that glycosyl donors substituted with this auxiliary form an intermediate beta-sulfonium ion, which reacts with alcohols to give exclusively alfa-glycosides.
 

General Posters
6:00 PM-8:00 PM, Tuesday, 28 March 2006 Georgia World Congress Center -- Ex. Hall B4, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 27 March 2006 Georgia World Congress Center -- Ex. Hall B4, Sci-Mix

Division of Carbohydrate Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006