摘要:

C-glycosylated aryl tins have been prepared as versatile building blocks of physiologically stable glycomimetics for glycoepitopes that have been recognized to serve biologically important roles in cell biochemistry.

ISSN:0732-8303    

DOI:10.1080/07328309908544002

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

C-glycosylated biphenyls were prepared by the palladium-mediated cross-coupling reaction ofC-glycosylated aryl tins with variously substituted aryl bromides, which will provide physiologically stable glycomimetics of various glycoepitopes. AC-sialylated biphenyl, a glycomimetic of biologically significant sialosides, is also available by this method.

ISSN:0732-8303    

DOI:10.1080/07328309908544003

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

C-glycosylated diphenylmethanes andC-glycosylated benzophenones were prepared by the palladium-catalyzed cross-coupling reaction ofC-glycosylated aryl tins with various benzyl bromides or acid chlorides to provide physiologically stable glycomimetics of miscellaneous glycoepitopes.

ISSN:0732-8303    

DOI:10.1080/07328309908544004

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The synthesis of several 3-aryl-5-glycosylisoxazole derivatives has been achieved. By condensation of the protected aldehydo-sugars 2,3-O-isopropylidene-D-glyceraldehyde (1), 2,3:4,5-di-O-isopropylidene-aldehydo-D-arabinose (2) and D-xylose (3), and 2,5-anhydro-3,4,5-tri-O-benzoyl-D-mannose (4) with benzoylmethylenetriphenylphosphorane, enulose derivatives were formed, which were later converted into a,ß-unsaturated ketoximes. These ketoximes were oxidatively cyclized with iodine and, after removal of the hydroxyl protecting groups, 3-phenyl-5-glycosylisoxazoles were formed.

ISSN:0732-8303    

DOI:10.1080/07328309908544005

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A total synthesis of the β-methyl glycoside of lacto-N-fucopentaose III (1) is described. Phenyl 2,3,4,6-tetra-O-benzoyl-β-D-galactopyranosyl-(1→4)-6-O-benzyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (4), a key intermediate prepared by condensation of 2,3,4,6-tetra-O-benzoyl-α-D-galactopyranosyl bromide (2) and phenyl 6-O-benzyl-2-deoxy-2-phthalimido-1-thio-β-D-glucopyranoside (3), was glycosylated with ethyl 2,3,4-tri-O-benzyl-1-thio-β-L-fucopyranoside (5) to give the trisaccharide donor6, which, on coupling with methyl 2,6-di-O-benzyl-β-D-galactopyranosyl-(1→4) 2,3,6-tri-O-benzyl-β-D-glucopyranoside (7), afforded the pentasaccharide8. It was easily transformed into the target pentasaccharide1via hydrazinolysis, acetylation,O-deacetylation, and hydrogenolysis.

ISSN:0732-8303    

DOI:10.1080/07328309908544006

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The push-pull-activated pyranosidulose2reacted with acetylacetone and methyl acetoacetate to afford the anellated pyranosides3and4, respectively. Treatment of the ulose2with acetoacetamide and malononitrile, respectively, furnished the fused pyridones5and6. Benzo-anellated pyranosides7were obtained by reaction of pyranosidulose2with dialkyl 3-oxoglutarates.

ISSN:0732-8303    

DOI:10.1080/07328309908544007

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

5-Azido-5-deoxy-1,2-O-isopropylidene-α-D-xylofuranose was used to obtain two reversed nucleoside analogues with either the 5-aminoimidazol-4-carboxamide or 5-amino-1,2,3-triazol-4-carboxamide groups attached, through the N1 site, to the C5′ site of the sugar. When deprotected these two compounds cyclised spontaneously and regiospecifically to form a bond between the exocyclic nitrogen and the anomeric carbon of the sugar. These reversed cyclonucleoside analogues are respectively members of the 2,5-epoxyimidazo[1,5-a][1,3]diazocine and 5,8-epoxy[1,2,3]triazolo[1,5-a][1,3]diazocine systems, novel ring systems with therapeutic potential. The shape of the cyclised imidazole compound and its immediate precursor has been studied by molecular modelling.

ISSN:0732-8303    

DOI:10.1080/07328309908544008

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Regio- and stereoselective synthesis of some trisaccharides was effected in high yields from coupling of acetobromolactose or acetobromomaltose as donors with partially protected glucoside acceptors through an orthoester formation-rearrangement strategy. Selective 1→6 or 1→3 with 1,2-transglycosylation was achieved.

ISSN:0732-8303    

DOI:10.1080/07328309908544009

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Ethylenediamine in admixture with acetic acid has been found useful to selectively effect the title conversion and can be of general utility. Reaction rates anomeric deacylations effected with this reagent are slower than with reagents introduced earlier, resulting in easier control and greater selectivity of deprotection.

ISSN:0732-8303    

DOI:10.1080/07328309908544010

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Artificial glycosides are used to prime the biosynthesis of glycosaminoglycan chains and those typical ofN- andO-linked oligosaccharides, e.g.,N-acetyllactosamine repeats.1-8Several studies have shown that the aglycon influences the amount and type of products assembled on such glycosides.2-6The amount of product made depends on two factors. The first is the ability of the glycoside to penetrate the plasma membrane and the Golgi membrane where the glycosyltransferases are located. The second is the structure of the aglycon since it can influence the addition of the first monosaccharide as well as extension with additional residues. In some instances, the aglycon is thought to mimic a portion of an underlying polypeptide chain.2-4,6The choice of aglycons is important, but there are no guidelines to direct the choice since many factors such as their stability to glycosidases, membrane-permeability, cellular toxicity or limitation of specificity and affinity can all be important. In the absence of such guidelines, we streamlined the process of aglycon evaluation and report here an efficient strategy to synthesize GlcNAcβ-R libraries with various aglycons.

ISSN:0732-8303    

DOI:10.1080/07328309908544011

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor