摘要:

The synthesis of three 2,3-unsaturated 4-amino sugars2-4and cyclohexyl 2,3-di-O-acetyl-4,6-di-O-methyl-α-D-mannopyranoside8starting from cyclohexyl 4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranoside1is described. The amino sugars were prepared by allylic substitution using a palladium catalyst.

ISSN:0732-8303    

DOI:10.1080/07328309908544023

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The X-ray diffraction analysis of methyl 3,4,6-tri-O-acetyl-2-deoxy-(3-phenylureido)-β-D-glucopyranoside was performed and showed that the molecules are associated by two NHz.O=C hydrogen bonds. One molecule with disorder of an acetyl group at C-4 was found in the asymmetric crystal unit. The signals in13C CPMAS NMR spectrum are duplicated indicating that local symmetry is lower than those of the crystal.

ISSN:0732-8303    

DOI:10.1080/07328309908544024

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Improved syntheses for the 3-β-D-glucuronides of the steroidal sex hormones 17β-estradiol, 17α-ethynylestradiol and estrone are reported employing boron trifluoride diethyl etherate catalysis with tetraacetylated glucuronic acid or the corresponding imidate.

ISSN:0732-8303    

DOI:10.1080/07328309908544025

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Selective protection for the individual hydroxyl groups of methyl (phenyl 3-deoxy-2-thio-β-D-glycero-D-galacto-2-nonulopyranosid)onate (2) was examined. The 4-, 5-, and 7-hydroxyl groups of methyl (phenyl 3-deoxy-8,9-O-isopropylidene-2-thio-β-D-glycero-D-galacto-2-nonulopyranosid)onate (3) were found selectively to be protected byt-butyldimethylsilyl, methoxymethyl, and benzoyl groups, respectively. In order to obtain the 8- and 9-hydroxyl derivatives selectively, methyl (phenyl 4,5,7-tri-O-acetyl-9-O-t-butyldimethylsilyl-3-deoxy-2-thio-β-D-glycero-D-galacto-2-nonulopyranosid)onate (12) and methyl (phenyl 4,5,7,8-tetra-O-benzyl-9-O-triphenylmethyl-3-deoxy-2-thio-β-D-glycero-D-galacto-2-nonulopyranosid)onate (19) were prepared in moderate yields.

ISSN:0732-8303    

DOI:10.1080/07328309908544026

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Convenient regio- and stereoselective syntheses of rhamnose-containing oligosaccharidesviasugar-sugar orthoester formation and rearrangement are described. 1→3 Linked rhamno di- and trisaccharides were synthesized effectively using unprotected rhamnose residue as the glycosyl acceptor by this methodology.

ISSN:0732-8303    

DOI:10.1080/07328309908544027

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Cyclic ketones1a-freacted with mercaptoacetic acid in benzene and/or toluene in the presence ofp-toluenesulfonic acid afforded the corresponding spiro-1,3-oxathialanone derivatives(2a-f). Compounds2a-freacted with glucosamine hydrochloride in a mixture of pyridine and ethanol to yield 3-(2′-glucosyl)-2-spiro[1′-cycloalkyl]thiazolidin-4-one derivatives4a-f. Reaction of4a-fwith fused sodium acetate in a mixture of acetic anhydride and acetic acid gave annulated spirothiazoloxazologlucose derivatives6a-f. All the synthesized spiro derivatives were identified by conventional methods (IR,1H NMR spectroscopy and elemental analyses).

ISSN:0732-8303    

DOI:10.1080/07328309908544028

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Treatment of methyl 2,3-di-O-benzyl-α-D-glucopyranoside (1), methyl 2,3-di-O-acetyl-α-D-glucopyranoside (4), 3-O-benzyl-1,2-O-(1-methylethylidene)-α-D-glucofuranose (6), 3-O-acetyl-1,2-O-(1-methylethylidene)-α-D-glucofuranose (9), 1,2-O-(1-methylethylidene)-α-D-xylofuranose (11) and methyl 2,3-di-O-acetyl-α-D-galactopyranoside (15) with diisopropylazodicarboxylate-triphenylphosphine in tetrahydrofuran led to the corresponding dioxaphosphoranes, which were opened by trimethylsilyl azide affording the silylated primary azidodeoxysugars. When the same reaction was performed on methyl 2,3-di-O-benzyl-α-D-galactopyranoside (20), an inversion of the regioselectivity of the dioxaphosphorane opening was observed, leading mainly to the 4-azido-4-deoxy-α-D-glucopyranoside derivative27.

ISSN:0732-8303    

DOI:10.1080/07328309908544029

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The synthesis of the title compounds started withN-acetylglucosamine which was converted into the corresponding methyl glycoside andO-protected with benzyl groups. SubsequentN-protection as itsN-BOC-N-acetyl derivative and sequential removal of theN-acetyl group and of the BOC group led in good yield to the target compounds in multigram amounts.

ISSN:0732-8303    

DOI:10.1080/07328309908544030

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

(2-Hydroxyethyl) 2-deoxy-α-D-threo-pentopyranoside 3,4,2′-trisphosphate (3) has been prepared starting from allyl-α-D-xylopyranoside. The suitably protected 2-deoxy intermediate obtained by judicious selective protection and deprotection has been phosphorylated using the phosphoramidite methodology. Final deprotection gave the expected analogue ofmyo-inositol 1,4,5-trisphosphate.

ISSN:0732-8303    

DOI:10.1080/07328309908544031

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The Horner-Wadsworth-Emmons (HWE) reaction was performed on methyl 3,6-di-O-benzoyl-2-deoxy-α-D-glycero-hex-2-enopyranosid-4-ulose (1) with the potassium enolates of dimethyl [(methoxycarbonyl)methyl]phosphonate (2) or diethyl [(ethoxycarbonyl) methyl]phosphonate (3) under different conditions (metallic cation and solvent) in order to study regio- and stereochemical aspects of the reaction. In the presence of lithium ions, no reaction took place. When sodium enolates were employed, 1,2-addition was the main reaction in chelating solvents, whereas the 1,4-adduct is favoured in the less polar, non chelating toluene. Only 1,2-addition was observed with potassium enolates. Evidence of phosphonate-phosphate rearrangements through five membered cyclic intermediates is described.

ISSN:0732-8303    

DOI:10.1080/07328309908544032

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor