title: Synthesis of a trisaccharide repeat of the zwitterionic Sp1 capsular polysaccharide utilizing 2-Azido-4-benzylamino-4N,3-O-carbonyl-2,4,6-trideoxy-d-galactopyranosyl trichloroacetimidate.
abstract: 2-Azido-4-benzylamino-4N,3-O-carbonyl-2,4,6-trideoxy-d-galactopyranosyl trichloroacetimidate 2 conveniently prepared in six steps from 6-deoxy-d-glucal glycosylated a selectively protected α1,3 linked methyl galabioside to afford the trisaccharide skeleton of a repeating unit of the Sp1 zwitterionic capsular polysaccharide. Lithium hydroxide hydrolysis of the 3,4-cyclic carbamate permitted the creation of a 2-acetamido-4-amino-2,4,6-trideoxygalactose residue. Selective cleavage of p-methoxybenzyl ethers by trifluoroacetic acid gave a selectively deprotected trisaccharide with two hydroxymethyl groups that were oxidized by the TEMPO reagent to afford access to trisaccharide glycoside 1 containing 2-acetamido-4-amino-2,4,6-trideoxygalactose and two galacturonic acid residues.
authors.affiliation: Alberta Ingenuity Centre for Carbohydrate Science and Department of Chemistry, The University of Alberta, Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada T6G 2G2.
authors.forename: Ithayavani
authors.initials: I
authors.lastname: Iynkkaran
authors.forename: David R
authors.initials: DR
authors.lastname: Bundle
mesh_terms: D001386:Azides / Q000737:chemistry*; D060326:Chemistry Techniques, Synthetic; D006031:Glycosylation; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000378:metabolism; D009844:Oligosaccharides / Q000138:chemical synthesis*; D011135:Polysaccharides, Bacterial / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D013296:Streptococcus pneumoniae / Q000737:chemistry*; D014312:Trisaccharides / Q000737:chemistry*
chemical_list: D001386:Azides; D009844:Oligosaccharides; D011135:Polysaccharides, Bacterial; D014312:Trisaccharides; D016753:Interleukin-10; D007371:Interferon-gamma
keywords: 2-Azido-4-benzylamino-4N,3-O-carbonyl 2,4,6-trideoxy-galactosyl donor; Cyclic carbamate hydrolysis by lithium hydroxide; Type I pneumococcal polysaccharide repeat; Uronic acid via post assembly oxidation; Zwitterionic trisaccharide; α-Glycosylation