摘要:

Two artificial antigens related toS.aureushave been synthesized to elucidate the influence of the phosphodiester bond in the immunogenicity of the natural ribitol teichoic acid.

ISSN:0732-8303    

DOI:10.1080/07328308508070181

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The synthesis of a protected pentasaccharide27bcorresponding to the antithrombin III binding region of heparin is presented. This pentasaccharide was prepared from two disaccharides (12cand23) and a monosaccharide (1). The glucuronic acid containing disaccharide12cwas prepared from easily available monomers 6 and 7. Oxidation to the uronic acid was performed in the disaccharide stage. L-Idose derivative16, prepared via a new route, was coupled with 1,6-anhydro derivative17, oxidized and transformed into disaccharide23. Coupling of12cand23to tetrasaccharide24ahas been investigated. Better yields were obtained without collidine, the reason for which is explained. Coupling of24band1afforded the pentasaccharide27b, protected with acetyl at the positions to be sulphated, benzyl at the other hydroxyl functions and azide at the 2-position of the glucosamine residues. Conversion of27binto the sulphated pentasaccharide Ib can be performed according to published procedures.

ISSN:0732-8303    

DOI:10.1080/07328308508070182

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Ferrier's intramolecular carbocyclic ring closure reaction of methyl 3,4-di-O-acetyl-2-benzoyl-amino-2,6-dideoxy-α-O-xylo-hex-5-enopyranoside (2) led to 2L-2,4,513-2,3-di-O-acetyl-4-benzoylamino-5-hydroxy-cyclohexanone (4). Upon acetylation compound4underwent B-elimination to give the conjugated enone5. The convenient preparation of these highly functionalized aminocyclohexanones offers an efficient route to monoamino- or 1,4-diaminocyclitol-type aminoglycoside antibiotic aglycones, starting from 2-amino-2-deoxy-O-glucose.

ISSN:0732-8303    

DOI:10.1080/07328308508070183

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Condensation reaction of 3,5-di-O-benzoyl-1,2-O-(1-cyanoben-zylidene)-β-D-arabinofuranose (2) with benzyl and allyl 2,3-di-O-benzoyl-5-O-triphenylmethyl-α-L-arabinofuranosides (5aand5b) in methylene chloride in the presence of triphenylcarbenium tetrafluoroborate as catalyst under high vacuum gave α-(1→5)-linked dimericD-arabinofuranoside derivatives (6aand6b). One of the dimeric compounds (6a) was debenzoylated, triphenylmethylated, and rebenzoylated to give a dimeric homolog of5a(8). Similarly for the preparation of6a, 8was condensed with2to provide an α-(1→5)-linked trimericD-arabinofuranoside derivative (9). Further elongation of the glycoside chain might be possible in the same way.

ISSN:0732-8303    

DOI:10.1080/07328308508070184

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Reaction of methyl [benzyl 2-[(benzyloxycarbonyl)-amino]-3-chloro-2,3,4-trideoxy-β-L-threo-hex-4-enopyrano-sid]uronate,3,4-trideoxy-β-L-threo-hex-4-enopyranosidjuronate (7) with silver fluoride gave the 5-fluoro, 3,4-unsaturated uronate derivative8, which, on treatment with methanolic ammonia, afforded the corresponding 5-meth-oxy, uronamide9. The structures of8and9were confirmed by spectral data and by x-ray crystallographic analysis of8.1H NMR spectroscopy parameters for 9 and its diastercomen11have been used to probe the conformational preferences in solution.

ISSN:0732-8303    

DOI:10.1080/07328308508070185

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Maillard polymers were prepared fromD-glucose-1 and -6-14C, glycine-1 and -2-14C, as well as C-1 and methyl-14C methionine, and the activities of the isolated polymers measured as a function of time. In both cases, C-1 of the amino acids were incorporated at the lowest levels, withD-glucose carbon atoms at the highest levels. The data support the conclusions that carbon dioxide, produced during the Maillard reaction, arises from C-1 of the amino acids, but also suggests that other carbons of the amino acids may contribute as well.

ISSN:0732-8303    

DOI:10.1080/07328308508070186

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The title disaccharide was prepared by glycosylation of either methyl trideuteriomethyl 2-O-benzoyl-4,6-benzylidene-β-D-galactopyranoside or trideuteriomethyl-4,6-O-benzylidene-β-D-galactopyranoside with 3,4,6-tri-Oi-acetyl 2-deoxy-2-phthalimido-β-D-glucopyranosyl bromide using silver zeolite 13X or silver triflate as promoters.

ISSN:0732-8303    

DOI:10.1080/07328308508070187

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

β-D-Glucosides of pyromeconic acid (3-hydroxy-4-oxo-4H-pyran), maltol (3-hydroxy-2-methyl-4-oxo-4H-pyran) and α-hydroxymaltol (3-hydroxy-2-hydroxymethyl-4-oxo-4H-pyran) were synthesized in one pot by reaction of stoichiometric amounts of acetobromoglucose and preformed hydroxypyrone anion followed by catalytic deacetylation with methanolic KOH. Products were identified and characterized by comparison of mp and molar rotation with literature, and by FAB-MS, negative ferric chloride test, and H-1 and C-13 NMR. All glycosides were levorotatory,betaand gave recognizable pseudo-molecular ions.

ISSN:0732-8303    

DOI:10.1080/07328308508070188

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The1H,13C and29Si NMR spectra of methyl β-D-xylopyranoside and three methyl β-D-xylopyranosyl-β-D-xylopyranosides have been measured and assigned by two-dimensional NMR spectroscopy. According to the determined proton-proton coupling constants, the ring conformer ratio is essential ly the same in the studied compounds. The assigned chemical shifts provide correct substituent chemical shifts for assignments in the spectra of higher trimethylsilylated xylooligosaccharides. Heteronuclear chemical shift correlated 2D NMR spectroscopy is proven to be a usable experimental method for29Si NMR line assignment in carbohydrates. The assigned silicon shifts identify the site of glycosidation.

ISSN:0732-8303    

DOI:10.1080/07328308508070189

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

1,6-Anhydro-β-D-giucopyranose was identified for the first time in aqueous solutions obtained by hydrothermolysis of cellulosic matter. The identification and quantitative determination of the 1,6-anhydro-β-D-glucopyranose, as well as of further degradation and conversion products, was accomplished by means of HPLC. For kinetic studies, 1,6-anhydro-β-D-glucopyranose was degraded in aqueous solution under hydrothermal conditions in the range of 200-240°C. A kinetic model covering both formation and decomposition of 1,6-anhydro-β-D-glucopyranose is proposed.

ISSN:0732-8303    

DOI:10.1080/07328308508070190

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor