Koenigs-Knorr Glycosylation with Neuraminic Acid Derivatives

Abstract

Earlier we reported a convenient and efficient method of preparing α2-6 sialooligosaccharides in conditions of Koenigs-Knorr reaction. The use of Ag 2 CO 3 allowed carrying out α2-6 sialylation of galacto-4,6-diol of mono- and disaccharides with chloride of acetylated N -acetylneuraminic acid methyl ester as glycosyl donor. In this study we applied this approach to other derivatives of neuraminic acid, namely, Neu5Gc, 9-deoxy-9-NAc-Neu5Ac, Neu5Acα2-8Neu5Ac, and Neu5Acα2-8Neu5Acα2-8Neu5Ac as glycosyl donors; eight compounds were synthesized: Neu5Gcα-O(CH 2 ) 3 NH 2 ( 8 ), Neu5Gcα2-6Galβ1-4GlcNAcβ-O(CH 2 ) 3 NH 2 ( 10 ), 9-deoxy-9-NAc-Neu5Ac-O(CH 2 ) 3 NH 2 ( 15 ), 9-deoxy-9-NAc-Neu5Acα2-6Galβ1-4GlcNAcβ-O(CH 2 ) 3 NH 2 ( 17 ), Neu5Acα2-8Neu5Acα-O(CH 2 ) 3 NH 2 ( 23 ) Neu5Acα2-8Neu5Acα-OCH 3 ( 24 ), Neu5Acα2-8Neu5Acα-OCH 2 ( p -C 6 H 4 )NHCOCH 2 NH 2 ( 25 ), and Neu5Acα2-8Neu5Acα2-8Neu5Acα-O(CH 2 ) 3 NH 2 ( 32 ). These sialosides were used for characterization of siglecs and other carbohydrate-binding proteins.