title: Synthesis of p-trifluoroacetamidophenyl 6-deoxy-2-O-(3-O-[2-O-methyl-3-O- (2-O-methyl-alpha-D-rhamnopyranosyl)-alpha-L-fucopyranosyl]-alpha-L- rhamnopyranosyl)-alpha-L-talopyranoside: a spacer armed tetrasaccharide glycopeptidolipid antigen of Mycobacterium avium serovar 20.
abstract: The synthesis of the title tetrasaccharide glycoside 38 is reported. p-Nitrophenyl endo-3,4-O-benzylidene-6-deoxy-alpha-L-talopyranoside (4), 3-O-acetyl-2,4-di-O-benzyl-alpha-L-rhamnopyranosyl trichloroacetimidate (7), methyl 3-O-acetyl-4-O-benzyl-2-O-methyl-1-thio-beta-L-fucopyranoside (15), 3-O-acetyl-4-O-benzyl-2-O-methyl-alpha-L-fucopyranosyl bromide (16), and ethyl 3-O-acetyl-4-O-benzyl-2-O-methyl-1-thio-alpha-D-rhamnopyranoside (33) were prepared as intermediates. Compound 4 was glycosylated with imidate 7 as well as with methyl 3-O-acetyl-2,4-di-O-benzyl-1-thio-alpha-L-rhamnopyranoside (9), affording the same disaccharide derivative 8. Deacetylation of 8 gave crystalline 17. Condensation of 17 with both fucosyl donors 15 and 16 yielded the same trisaccharide derivative 18 stereoselectively. Compound 18 was also prepared by the coupling of 4 with disaccharide glycosyl donor 20. After deacetylation of 18 (-->34), methyl triflate-promoted glycosylation with compound 33 resulted in tetrasaccharide 35. Conversion of the p-nitrophenyl group of 35 into the p-trifluoroacetamidophenyl group (-->36) and removal of the protecting groups gave the title tetrasaccharide glycoside 38.
authors.affiliation: Institute of Biochemistry, L. Kossuth University, Debrecen, Hungary.
authors.forename: J
authors.initials: J
authors.lastname: Kerékgyártó
authors.forename: Z
authors.initials: Z
authors.lastname: Szurmai
authors.forename: A
authors.initials: A
authors.lastname: Lipták
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009162:Mycobacterium avium / Q000737:chemistry*; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D009904:Optical Rotation
chemical_list: C082836:4-trifluoroacetamidophenyl 6-deoxy-2-O-(3-O-(2-O-methyl-3-O-(2-O-methyl-rhamnopyranosyl)-alpha-fucopyranosyl)-alpha-rhamnopyranosyl)-alpha-talopyranoside; D007202:Indicators and Reagents; D009844:Oligosaccharides