/npsi/ctrl?action=rtdoc&an=17364211&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=17364211&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions?Contact the NRC Publications Archive team at PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1021/jo1016579Journal Of Organic Chemistry, 76, 4, pp. 1045Chemistry, 76, 4, pp. -1053Chemistry, 76, 4, pp. , 2011 1,2-Cyclopropaneacetylated sugars as glycosyl donors reacted with a series of glycosyl acceptors (monosaccharides, amino acids, and other alcohols) in the presence of Lewis acid to produce oligosaccharides and glycoconjugates containing 2-C-acetylmethylsugars. Galactosyl donor gave good to excellent R-selectivities with TMSOTf as a catalyst, whereas galactosyl donor offered moderate to good β-selectivities when BF 3 3 Et 2 O was used as a catalyst. However, glucosyl donors produced β-exclusive selectivity under both conditions. The stereoselectivities of glycosylation depend on the reactivity of donor sugars and Lewis acid catalyst, which effectively dictated the glycosylation pathways. The evidence suggests that galactosyl donors (e.g., 7) can undergo S N 1 pathway with a strong Lewis acid (TMSOTf) and S N 2 pathway under BF 3 3 Et 2 O, whereas the glucosyl donors (e.g., 8 and 10) followed S N 2 pathway. The stereoselectivity was also consequential to the formation of a C2 0 -acetal intermediate formed via the 2-C-acetylmethyl group and the anomeric carbonium intermediate in glycosylation.

ABSTRACT1,2-Cyclopropaneacetylated sugar is an effective glycosyl donor, which reacted with various glycosyl acceptors including monosaccharides, amino acids and other alcohols in the presence of BF 3 •OEt 2 or TMSOTf. The glycosylation is stereoselective in favor of -anomeric products with BF 3 •OEt 2 as catalyst, whereas TMSOTf-catalyzed glycosylation prefers the r-anomeric products. 2-C-Acetonyl-2-deoxy-D-galactosides were obtained in good yields.2-Acetamido-2-deoxy-D-glycopyranosides are widely distributed in living organisms as oligosaccharides and glycoconjugates, and play essential roles in a wide range of biological processes. 1 Hence, there is a considerable interest in glycan and glycoconjugate mimics with modified 2-Nacetamidosugar residues for further understanding and modulating the targets of these glycosides. 2 Among the various analogs, 2-acetonyl-2-deoxy-D-galactose (2-keto-Gal) has gained much attention. 3 This substrate can serve as ketone isostere of GalNAc for cell surface engineering, 4 conjugation of nonglycoprotein with biomolecules, 5 and labeling of a single-chain antibody. 6 Moreover, 2-keto-Gal has been taken as a substrate for mutant GalT to detect O-GlcNAc-glycosylated proteins, 7 and the LacNAc moiety of glycoproteins and glycolipids. 8 Notably, it may function as a linker substrate to assemble glycoconjugates with therapeutic and diagnostic applications. 6,9 † Chengdu Institute of Biology. ‡ National Research Council of Canada.(1) (a) Dwek, R. A. Chem. ReV. 1996, 96, 683-720. (b)