title: Synthesis of branched polysaccharides by polymerization of 6-O-t-butyldimethylsilyl-D-glucal through stereoregular haloglycosylation.
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.
authors.affiliation: Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Japan.
authors.forename: J I
authors.initials: JI
authors.lastname: Kadokawa
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Tagaya
authors.forename: K
authors.initials: K
authors.lastname: Chiba