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Two phosphite sialyl donors, each having an auxiliary 3-(S)-phenylseleno group, were prepared and evaluated. The phenylseleno group was introduced via a new mode of generating phenylselenenic acid (‘PhSeOH’). Although the sialyl donors provided fair yields (32–76%) of the desired sialosides in glycosylations of the reactive acceptor 1,2;3,4-di-O-isopropylidene-α-d-galactopyranose, no sialylated pr
A practical procedure for the synthesis of water-soluble, chiral and amphiphilic macrocyclic molecules is described. Acylation of p-xylylene diamine with Fmoc-protected glycine and aspartic acid, followed by removal of the Fmoc moiety afforded amino acid:p-xylene conjugates as free diamines. These diamines were converted to symmetrical and unsymmetrical macrocycles via stepwise urea formation u
A one-pot synthesis of the globotetraose tetrasaccharide is reported. The synthetic method relies on the use of a p-methoxybenzyl ether as an in situ-removable protecting group. N-Iodosuccinimide/trifluoromethanesulfonic acid-promoted glycosylation of 2-bromoethyl-2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-β-D-galactopyranosyl)-β-D-glucopyranoside 5 at −45 °C with phenyl 2,4,6-tri-O-benzyl-3-O-(
Solid-phase extraction (SPE) has during the last three years emerged as a convenient method for the purification of compound libraries prepared by solution synthesis. The widespread use of SPE in combinatorial chemistry can be explained by straightforward SPE method development facilitated by the availability of numerous commercial SPE resins. High-speed automated SPE is readily accomplished by ta
Treatment of 2-(trimethylsilyl)ethyl sulfides with a carboxylic acid chloride and AgBF4 in CH2Cl2 furnishes the corresponding thioesters in high yields and purities. The conversion of 2-(trimethylsilyl)ethyl sulfides into synthetically versatile thioesters allows such sulfides to be used as sulfhydryl protective groups, since such sulfides are easily prepared and are stable towards many reaction c
Parallel solution S-alkylations of a 1-thio-β-D-galactopyranoside derivative with Michael acceptors and α-chloroketones, followed by ketone reductions, reductive aminations, and acylations were developed to yield a library of 1-thio-β-D-galactopyranosides carrying small and diverse polar- neutral, hydrophobic, aromatic, cationic, or anionic non-carbohydrate aglycon structures. Screening of the lib
The NMR data obtained from hydroxy protons have been used to investigate the presence and absence of intramolecular hydrogen bonding in aqueous solutions of 2-(trimethylsilyl)ethyl galabioside (α-D-Galp-(1→4)-β-D-Galp-O(CH2)2SiMe3) and the S-linked 4-thiodisaccharide analogue. The data show that there is a weak hydrogen bond interaction between O-6H and O-2'H in galabioside, but not in the thio-an
A novel strategy for the purification of carbohydrate-based chemical libraries synthesized in solution was developed. Purification of reaction products was accomplished by means of solid-phase extraction enabled by protecting the 2-, 3-, 4-, and 6-hydroxyl groups of a galactose derivative as their hydrophobic O-laurates. The presence of multiple O-laurates allowed adsorption of reaction products o
A simple and economical procedure for the attachment of reducing sugars to aminated solid supports has been developed. Reaction of the amino groups on the solid support with p-nitrophenyl chloroformate, followed by 1,6-hexanediamine, yields a chain-extended amine to which reducing sugars can be attached while remaining accessible to macromolecules. Immobilization of the reducing sugars involves a
Purified PapG adhesin from the genetically well-defined uropathogenic Escherichia coli strain J96, as well as whole bacteria, were bound to microtiter plates that carried covalently bound globotetraose and galabiose. The binding was inhibited by soluble saccharide derivatives corresponding to the globoseries of glycolipids, including all di-, tri-, tetra-, and pentasaccharide fragments of the Fors
Starch from genetically modified potatoes was found to be highly branched compared with normal potato varieties through the use of 1H-NMR spectroscopy. The average chain length, blue-value,and the wavelength at maximum absorptivity clearly show that the new potato varieties produce amylopectin starch. Correlation between the degree of branching as determined by 1H-NMR and starch-iodine complexatio
The two thio analogues (2 and 3) of TMSEt galabioside [2-(trimethylsilyl) ethyl 4-O-(α-D-galactopyranosyl)-β-D-galactopyranoside, 1], having anomeric sulfur instead of anomeric oxygen atoms, were synthesized and their conformations investigated by NMR and computational (MM3) methods. A spacer galabioside was covalently coupled to aminated microtiter plates, and binding of a bacterial pilus adhesin
Different forms of major histocompatibility complex (MHC) class I heavy chains are known to be expressed on the cell surface, including molecules which are functionally 'empty'. Direct peptide binding to cells is obvious during sensitization of target cells in vitro for cytotoxic T lymphocyte killing and 'empty' MHC-I molecules are comparatively abundant on TAP- 1 2 peptide transporter mutant cell
Background and aimsElevated body weight in adolescence is associated with early cardiovascular disease, but whether this association is traceable to weight in early adulthood, weight in midlife or to weight gain is not known. The aim of this study is to assess the risk of midlife coronary atherosclerosis being associated with body weight at age 20, body weight in midlife and body weight change.Met
The binding of uropathogenic Escherichia coli to the globo series of glycolipids via P pili is a critical step in the infectious process that is mediated by a human‐specific PapG adhesin. Three classes of PapG adhesins exist with different binding specificities to Galα4Gal‐containing glycolipids. The structural basis for PapG recognition of the human glycolipid receptor globoside was investigated
Ganglioside lactams are potentially useful analogs of ganglioside lactones, which are highly immunogenic derivatives of gangliosides. The lactam corresponding to the GM3-lactone saccharide has been synthesized by sialylation of a suitably protected lactose derivative carrying an azido group in the 2'-position, followed by reduction and ring closure to form GM3-lactam. Glycosylation in the 4-positi
The pentasaccharide glycoside corresponding to galactosylgloboside (SSEA-3), β-d-Gal p-(1 → 3)-β-d-Gal pNAc-(1 → 3)-α-d-Gal p-(1 → 4)-β-d-Gal p-(1 → 4)-β-d-Glc p-1-OCH2CH2Si-(CH3)3 (4), was synthesized via glycosylation (87%) of 2-(trimethylsilyl)ethyl 2,3,6-tri-O-benzyl-4-O-[2,3,6-tri-O-benzyl-4-O-(2,4,6-tri-O-benzyl-α-d-galactopyranosyl)-β-d- galactopyranosyl]-β-d-glucopyranoside (2) with the gl
The 1H and 13C NMR parameters, i.e., chemical shifts and coupling constants, for the pentasaccharide of the Forssman antigen and overlapping di-, tri-, and tetra-saccharide sequences thereof have been measured and assigned completely using 1D and 2D techniques, and the oligosaccharide structures have thereby been confirmed. Nuclear Overhauser effect (NOE) experiments have been carried out at three
