title: [Synthesis of disaccharide Neu5Gcalpha(2-6)GalNAcalpha as a spacer glycoside].
abstract: The first synthesis of the Neu5Gc analogue of SiaTn disaccharide, which can be detected in breast tumors by immunochemical methods, is reported. The regioselective sialylation of (3-trifluoroacetamidopropyl)-2-azido-2-deoxy-alpha-D-galactopyranoside with peracetate of the methyl ester of N-acetoxyacetylneuraminic acid beta-ethylthioglycoside in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid (or its trimethylsilyl ester) resulted in the derivatives of alpha- and beta-sialyl(2-->6)galactosaminide in 39 and 32% yields, respectively. The catalytic hydrogenolysis of the azido group and subsquent N- and O-acetylation of the alpha-anomer gave the trifluoroacetamidopropyl glycoside peracetate. Removal of the protective groups led to glycoside Neu5Gc alpha(2-->6)GalNAc alpha-O(CH2)3NH2. Using the Neu5Gc derivative with acetoxyacetyl groups at positions O9 and O4 as a donor increases the alpha-selectivity of sialylation to afford the alpha- and beta-anomers in 69 and 8% yields, respectively.
authors.affiliation: Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia.
authors.forename: L A
authors.initials: LA
authors.lastname: Simeoni
authors.forename: N E
authors.initials: NE
authors.lastname: Baĭramova
authors.forename: N V
authors.initials: NV
authors.lastname: Bovin
mesh_terms: D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000378:metabolism; D004187:Disaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D005260:Female; D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry*; D006801:Humans; D019158:N-Acetylneuraminic Acid; D009438:Neuraminic Acids
chemical_list: D014408:Biomarkers, Tumor; D004187:Disaccharides; D006027:Glycosides; D009438:Neuraminic Acids; C032592:N-glycolylneuraminic acid; D019158:N-Acetylneuraminic Acid