title: Iodonium ion-assisted synthesis of a haptenic tetrasaccharide fragment corresponding to the inner cell-wall glycopeptidolipid of Mycobacterium avium serotype 4.
abstract: Condensation of ethyl 2,4-di-O-benzoyl-1-thio-alpha-L-rhamnopyranoside with ethyl 3-O-benzyl-4-O-chloroacetyl-2-O-methyl-1-thio-beta-L-fucopyranoside in the presence of iodonium di-sym-collidine perchlorate afforded exclusively ethyl 2,4-di-O-benzoyl-3-O-(3-O-benzyl-4-O- chloroacetyl-2-O-methyl-alpha-L-fucopyranosyl)-1-thio-alpha-L-rhamnop yra noside. This disaccharide derivative was extended at C-1 with 3-benzyloxycarbonylaminopropyl 6-deoxy-3,4-O-isopropylidene-alpha-L- talopyranoside, using N-iodosuccinimide and triflic acid as the catalyst, to furnish 3-benzyloxycarbonylaminopropyl 6-deoxy-2-O-[2,4-di-O-benzoyl-3-O-(3-O-benzyl-4-O-chloroacetyl-2-O-me thy l- alpha-L-fucopyranosyl)-alpha-L-rhamnopyranosyl]-3,4-O-isopropylidene-alp ha-L- talopyranoside (20). Selective removal of the chloroacetyl group from 20, followed by condensation with ethyl 2,3-di-O-benzoyl-4-O-methyl-1-thio-alpha-L- rhamnopyranoside in the presence of the same thiophilic promoter, yielded a fully protected tetrasaccharide derivative. Deprotection of the latter gave the target compound 3-aminopropyl 6-deoxy-2-O-[3-O-[2-O- methyl-(4-O-methyl-alpha-L-rhamnopyranosyl)-alpha-L-fucopyranosyl]-alpha -L- rhamnopyranosyl]-alpha-L-talopyranoside (1).
authors: Gorlaeus Laboratories, Department of Chemistry, Leiden University, Netherlands.
authors: H M
authors: HM
authors: Zuurmond
authors: G H
authors: GH
authors: Veeneman
authors: G A
authors: GA
authors: van der Marel
authors: J H
authors: JH
authors: van Boom
mesh_terms: D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000737:chemistry*; D004187:Disaccharides / Q000138:chemical synthesis; D006017:Glycolipids; D006020:Glycopeptides; D006241:Haptens / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015269:Mycobacterium avium Complex / Q000737:chemistry*; D009844:Oligosaccharides / Q000138:chemical synthesis*; D009861:Onium Compounds / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D013237:Stereoisomerism; D014312:Trisaccharides / Q000138:chemical synthesis
chemical_list: D004187:Disaccharides; D006017:Glycolipids; D006020:Glycopeptides; D006241:Haptens; D009844:Oligosaccharides; D009861:Onium Compounds; D011725:Pyridines; D014312:Trisaccharides; C010762:peptidoglycolipids; C080715:3-aminopropyl 6-deoxy-2-O-(3-O-(2-O-methyl-(4-O-methylrhamnopyranosyl)fucopyranosyl)rhamnopyranosyl)talopyranoside; C080714:iodonium dicollidine