ABSTRACTSTEREOSELECTIVE GLYCOSYLATIONS AND SYNTHESIS OF HYALURONAN SYNTHESIS INHIBITORSByGilbert Ochieng WasongaStereochemical control is an important issue in carbohydrate synthesis. Glycosyl donors with participating acyl protective groups on 2-O have been shown to give 1,2-trans glycosides reliably under the pre-activation based reaction condition. In this work, the effects of additives and reaction solvent on stereoselectivity was examined using donors without participating protective groups on 2-O. We have established that the stereoselectivity could be directed by reaction solvent. The trend of stereochemical dependence on reaction solvent was applicable to a variety of reactions including the selective formation of -mannosides. In the second part, 3-MeO-GlcNAc is efficiently prepared using a furanose oxazoline intermediate which is well suited for large scale synthesis without the need for extensive column chromatography. In addition, we have developed a robust and rapid procedure for the synthesis of 3-F-GlcNAc derivative required for inhibition studies of hyaluronan biosynthesis. In the course of our synthesis, we have shown the expanded utility of Lattrell-Dax method for carbohydrate epimerization reactions.
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