Synthesis of branched polysaccharides by polymerization of 6-O-t-butyldimethylsilyl-D-glucal through stereoregular haloglycosylation |
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Authors: | Kadokawa J I Yamamoto M Tagaya H Chiba K |
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Affiliation: | Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Japan. |
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Abstract: | In this letter, we report synthesis of branched polysaccharide 2 by glycosylation of glucal-type monomer 1 with two free hydroxy groups at position 3 and 4. Monomer 1 polymerized with N-halosuccinimide promoter in acetonitrile solvent at room temperature--50 degrees C. The product was isolated as a petroleum ether insoluble fraction. The structure was determined by 1H and 13C NMR spectra as well as elemental analysis to be a polysaccharide consisting of 2-halo-2-deoxy-alpha-D-mannoside units, indicating that the polymerization proceeded via stereoregular glycosylation manner. The molecular weights determined by GPC with DMF were 3,300-4,000. The degree of branching was estimated by the NMR data of the product from the reaction of 2 with 3,5-dinitrobenzoyl chloride. |
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