Thiosugar nucleotide analogs: synthesis of 5'-(2,3,4-tri-O-acetyl-6-S-acetyl-6-thio-alpha-D-galactopyranosyl diphosphate)

Straightforward S-S Bond Formation via the Oxidation of S-Acetyl by Iodine in the Presence of N-Iodosuccinimide

Straightforward S-S bond formation via the oxidation of S-acetyl group by iodine was reported here. The reaction was further applied in the synthesis of per-O-acetylated glycosyl disulfides. These studies demonstrated great improvement in reaction rate, yield, and general convenience in the presence of N-iodosuccinimide. Furthermore, selectively deacetylated glycosyl thiols were obtained in high yields when these per-O-acetylated glycosyl disulfides were reduced with tris(2-carboxyethyl)-phosphine (TCEP). Our method supplied an efficient way to obtain both per-O-acetylated glycosyl disulfides and per-O-acetylated glycosyl thiols in which the sulfur group was located at any position.

Chemical synthesis of UDP-Glc-2,3-diNAcA, a key intermediate in cell surface polysaccharide biosynthesis in the human respiratory pathogens B. pertussis and P. aeruginosa

In connection with studies on lipopolysaccharide biosynthesis in respiratory pathogens we had a need to access potential biosynthetic intermediate sugar nucleotides. Herein we report the chemical synthesis of uridine 5'-diphospho 2,3-diacetamido-2,3-dideoxy-alpha-D-glucuronic acid (UDP-Glc-2,3-diNAcA) (1) from N-acetyl-D-glucosamine in 17 steps and approximately 9% overall yield. This compound has proved invaluable in the elucidation of biosynthetic pathways leading to the formation of 2,3-diacetamido-2,3-dideoxy-D-mannuronic acid-containing polysaccharides.

Synthesis of UDP-glucose derivatives modified at the 3-OH as potential chain terminators of beta-glucan biosynthesis

A series of UDP-D-glucose derivatives and precursors that have been modified at C-3 were synthesised from D-glucose as potential chain terminators of beta-glucan biosynthesis. None of the UDP-derivatives or the precursors tested displayed significant anti-fungal activity in a series of germination assays on the dermatophyte Trichophyton rubrum.

Syntheses of the 3- and 4-thio analogues of 4-nitrophenyl 2-acetamido-2-deoxy-beta-D-gluco- and galactopyranoside

The syntheses of 4-nitrophenyl beta-glycosides of the 3-thio and 4-thio analogues of the two principal 2-acetamido-2-deoxy-hexoses found in living systems, GlcNAc and GalNAc, are described. While synthesis of the 4-thio analogues could be achieved via nucleophilic displacements of sulfonate derivatives with thioacetate, problems with neighbouring group acetamido participation necessitated the use of sulfamidate intermediates for the 3-thio analogues. These 3- and 4-thio analogues are employed in the chemo-enzymatic synthesis of thio-oligosaccharide analogues of structures present in glycosaminoglycans, glycoproteins and glycolipids.

Synthesis of fluorescently labeled UDP-GlcNAc analogues and their evaluation as chitin synthase substrates

[structure: see text] Chitin synthase (CS) polymerizes UDP-GlcNAc to form chitin (poly-beta(1,4)-GlcNAc), a key component of fungal cell wall biosynthesis. Little is known about the substrate specificity of chitin synthase or the scope of substrate modification the enzyme will tolerate. Following a previous report suggesting that 6-O-dansyl GlcNAc is biosynthetically incorporated into chitin, we became interested in developing an assay for CS activity based on incorporation of a fluorescent substrate. We describe the synthesis of two fluorescent UDP-GlcNAc analogues and their evaluation as chitin synthase substrates.

The Synthesis of Various 1,6-Disulfide-Bridged D-Hexopyranoses

1,6-Disulfide-bridged derivatives have been prepared for d-gluco-, d-manno-, d-allo-, d-galacto-, and d-talo-pyranose, in the main by the nucleophilic attack of a C6 thiolate onto an anomeric thiosulfonate. The d-gluco disulfide, ‘angyalosan’, was successfully oxidized to a single thiosulfinate.

Synthesis of uridine 5'-[2-S-pyridyl-3-thio-alpha-D-galactopyranosyl diphosphate]: precursor of UDP-thiogal sugar nucleotide donor substrate for beta-1,4-galactosyltransferase

The syntheses of a novel uridine diphosphate galactose (UDP-Gal) analog, (UDP-2,4,6-tri-O-acetyl-3-S-acetyl-3-thio-alpha-D-galactopyranose) (11) and the thiolpyridine protected (Uridine 5'-[3-S-(2-S-pyridyl)-3-thio-alpha-D-galactopyranosyl diphosphate) analog (12) are described. The reported synthesis relies on the novel use of thiolpyridine to generate 12 which is a suitably protected intermediate for generating a UDP-thioGal derivative by reduction prior to enzyme transfer via beta-1,4-galactosyltransferase.