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1.
Condensation of 4,6-di-O-acetyl-2,3-O-carbonyl-α-d-mannopyranosyl bromide with benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside (2) gave an α-d-linked disaccharide, further transformed by removal of the carbonyl and benzylidene groups and acetylation into the previously reported benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl)-α-d-glucopyranoside. Condensation of 3,4,6-tri-O-benzyl-1,2-O-(1-ethoxyethylidene)-α-d-glucopyranose or 2-O-acetyl-3,4,6-tri-O-benzyl-α-d-glucopyranosyl bromide with 2 gave benzyl 2-acetamido-3-O-(2-O-acetyl-3,4,6-tri-O-benzyl-β-d-glucopyranosyl)-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside. Removal of the acetyl group at O-2, followed by oxidation with acetic anhydride-dimethyl sulfoxide, gave the β-d-arabino-hexosid-2-ulose 14. Reduction with sodium borohydride, and removal of the protective groups, gave 2-acetamido-2-deoxy-3-O-β-d-mannopyranosyl-d-glucose, which was characterized as the heptaacetate. The anomeric configuration of the glycosidic linkage was ascertained by comparison with the α-d-linked analog.  相似文献   

2.
Synthetic routes are discussed to the branched d-mannopentaoside methyl 6-O-(2,6-di-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-3-O-α-d-mannopyranosyl-α-d-mannopyranoside and d-mannohexaoside methyl 6-O-(2,6-di-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-3-O-(2-O-α-d-mannopyranosyl-α-d-mannopyranosyl)- α-d-mannopyranoside, employing the properly benzylated d-mannobioside methyl 2,4-di-O-benzyl-6-O-(3,4-di-O-benzyl-α-d-mannopyranosyl)-α-d-mannopyranoside and d-mannotrioside methyl 2,4-di-O-benzyl-6-O-(3,4-di-O-benzyl-α-d-mannopyranosyl)-3-O-(3,4,6-tri-O-benzyl-α-d-mannopyranosyl)-α-d- mannopyranoside as key intermediates.  相似文献   

3.
《Carbohydrate research》1987,165(2):207-227
8-Methoxycarbonyloctyl 2-azido-4,6-O-benzylidene-2-deoxy-β-d-mannopyranoside reacted with 2,3,4-tri-O-acetyl-α-l-rhamnopyranosyl bromide to give a disaccharide from the which the glycosyl-acceptor 8-methoxycarbonyloctyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(2,4,-di-O-acetyl-α-l-rhamnopyranosyl)-β-d-manno pyranoside (19) was obtained. This glycosyl-acceptor with 2,3,4,6-tetra-O-benzyl-α-d-glucopyranosyl chloride to give trisaccharide derivative 22 and with 2,3,6-tri-O-(α-2H2)benzyl-4-O-(2,3,4,6-tetra-O-(α-2H2)benzyl-α-d-glucopyranosyl)-α-d-glucopyranosyl chloride to give tetrasaccharide derivative 29. Deblocking of 22 yielded 8-methoxycarbonyloctyl O-(α-d-glucopyranosyl)-(1→3)-O-α-l-rhamnopyranosyl-(1→3)-2-acetamido-2-deoxy-β-d-mannopyranoside and deblocking of 29 8-methoxycarbonyloctyle O-α-d-glucopyranosyl-(1→4)-O-α-d-glucopyranosyl-(1→3)-O-α-l-rhamnopyranosyl- (1→3)-2-acetamido-2-deoxy-β-d-mannopyranoside. Both oligosaccharides represent the “repeating unit” of the O-specific chain of the lipopolysaccharide from Aeromonas salmonicida.  相似文献   

4.
Synthetic routes are described to the d-mannopentaoside methyl 3-O-(3,6-di-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-6-O-α-d-mannopyranosyl-α-d-mannopyranoside, and the d-mannohexaoside methyl 3-O-(3,6-di-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-6-O-(2-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-α- d-mannopyranoside, formed in a regio- and stereo-controlled way by employing the properly protected d-mannobioside methyl 2,4-di-O-benzyl-3-O-(2,4-di-O-benzyl-α-d-mannopyranosyl)-α-d-mannopyranoside and d-mannotrioside methyl 2,4-di-O-benzyl-3-O-(2,4-di-O-benzyl-α-d-mannopyranosyl)-6-O-(3,4,6-tri-O-benzyl-α-d- mannopyranosyl)-α-d-mannopyranoside as key intermediates.  相似文献   

5.
Methyl 2-O-allyl-4,6-O-benzylidene-3-O-(2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl)-α-d-mannopyranoside(12) was prepared in 90 % yield by Helferich glycosylation of methyl 2-O-allyl-4,6-O-benzylidene-α-d-mannopyranoside (9) with tetra-O-acetyl-α-d-mannopyranosyl bromide (11). Removal of the benzylidene group and second Helferich glycosylation with 11 led to methyl 2-O-allyl-3,6-di-O-(2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl)-α-d-mannopyranoside (14) which, after deallylation and Zemplén deacetylation, gave the title compound 5. The disaccharides methyl 3-O-(α-d-mannopyranosyl)-α-d-mannopyranoside (7) and methyl 6-O-(α-d-mannopyranosyl)-α-d-mannopyranoside (6) have also been synthesized. Complete assignments of the 1H-n.m.r. spectra of the compounds 5, 6, and 7 are given.  相似文献   

6.
Efficient syntheses are described of the branched d-mannopentaosides methyl 2,6-di-O-(2-O-α-d-mannopyranosyl-α-d-mannopyranosyl)α-d-mannopyranoside and methyl 2,4-di-O-(2-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-α-d-mannopyranoside, starting from the glycosyl acceptors methyl 3,4-di-O-benzyl-α-d-mannopyranoside and methyl 3,6-di-O-benzyl-α-d-mannopyranoside, and employing the protected d-mannotriosides methyl 3,4-di-O-benzyl-2,6-di-O-(3,4,6-tri-O-benzyl-α-d-mannopyranosyl)-α-d-mannopyranoside, and methyl 3,6-di-O-benzyl-2,4-di-O-(3,4,6-tri-O-benzyl-α-d-mannopyranosyl)-α-d-mannopyranoside as key intermediates.  相似文献   

7.
The two purple-membrane glycolipids O-β-d-glucopyranosyl- and O-β-d-galactopyranosyl-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2, 3-di-O-phytanyl-sn-glycerol were prepared by coupling O-(2,3,4-tri-O-acetyl-α-d-mannopyranosyl)-(1→2)-O-(3,4,6-tri-O-acetyl-α-d-glucopyranosyl)-(1→1)-2, 3-di-O-phytanyl-sn-glycerol (9) with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide or 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide, respectively, followed by deacetylation. The glycolipid sulfate O-(β-d-glucopyranosyl 3-sulfate)-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2,3-di-O-phytanyl-sn-glycerol was prepared by coupling of 9 with 2,4,6-tri-O-acetyl-3-O-trichloroethyloxycarbonyl-α-d-glucopyranosyl bromide in the presence of Hg(CN)2/HgBr2 followed by selective removal of the 3?-trichloroethyloxycarbonyl group, sulfation of HO-3?, and deacetylation. The suitably protected key-intermediate 9 could be prepared by two distinct approaches.  相似文献   

8.
The oligosaccharide β-d-Man-(1 → 4)-α-l-Rha (1 → 3)-d-Gal-(6 ← 1)-α-d-Glc, which is the repeating unit of the O-specific polysaccharide chain of the lipopolysaccharide from Salmonella senftenberg, was obtained by glycosylation of benzyl 2,4-di-O-benzyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside or benzyl 2-O-acetyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside with 3-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl)-β-l-rhamnopyranose 1,2-(methyl orthoacetate) followed by removal of protecting groups.  相似文献   

9.
Glycosylation of 1,2:5,6-di-O-isopropylidene-α-d-galactofuranose with 2,3-di-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl)-α-l-rhamnopyranosyl bromide, followed by removal of the protecting groups, gave O-β-d-mannopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→3)-d-galactose, which is the trisaccharide repeating-unit of the O-specific polysaccharide chain of the lipopolysaccharide from Salmonella anatum. The formation of the β-d-mannopyranosyl linkage was achieved by a glucose-mannose conversion via stereoselective reduction of the corresponding oxo-disaccharide.  相似文献   

10.
Silver trifluoromethanesulfonate-promoted condensation of 3,4,6-tri-O-acetyl-2-deoxy-phthalimido-β-d-glucopyranosyl bromide with benzyl 3,6-di-O-benzyl-α-d-mannopyranoside and benzyl 3,4-di-O-benzyl-α-d-mannopyranoside gave the protected 2,4- and 2,6-linked trisaccharides in yields of 54 and 32%, respectively. After exchanging the 2-deoxy-2-phthalimido groups for 2-acetamido-2-deoxy groups and de-blocking, the trisaccharides 2,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-mannose and 2,6-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-mannose were obtained. Similar condensation of 3,6-di-O-acetyl-2-deoxy-2-phthalimido-4-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-β-d-glucopyranosyl bromide with benzyl 3,4-di-O-benzyl-α-d-mannopyranoside gave a pentasaccharide derivative in 52% yield. After transformations analogous to those applied to the trisaccharides, 2,6-di-O-[β-d-galactopyranosyl-(1→4)-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)]-d-mannose was obtained.  相似文献   

11.
Condensation of benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside with 2,3,4,6-tetra-O-benzyl-1-O-(N-methyl)acetimidoyl-β-D-glucopyranose gave benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-(2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl)-α-D-glucopyranoside which was catalytically hydrogenolysed to crystalline 2-acetamido-2-deoxy-4-O-α-D-glucopyranosyl-α-D-glucopyranose (N-acetylmaltosamine). In an alternative route, the aforementioned imidate was condensed with 2-acetamido-3-O-acetyl-1,6-anhydro-2-deoxy-β-D-glucopyranose, and the resulting disaccharide was catalytically hydrogenolysed, acetylated, and acetolysed to give 2-acetamido-1,3,6-tri-O-acetyl-2-deoxy-4-O-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl)-α-D-glucopyranose Deacetylation gave N-acetylmaltosamine. The synthesis of 2-acetamido-2-deoxy-4-O-β-D-glucopyranosyl-α-D-glucopyranose involved condensation of benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide in the presence of mercuric bromide, followed by deacetylation and catalytic hydrogenolysis of the condensation product.  相似文献   

12.
Quaternary ammonium and phosphonium salts were readily obtained by treating 2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl bromide with tertiary amines and phosphines in various solvents under anhydrous conditions. Optical rotations and n.m.r. spectra of the hygroscopic syrups indicated that they exist mainly in the β-D configuration. Several dialkyl sulfides reacted very slowly with the galactosyl bromide and no conclusive evidence for sulfonium salt formation was obtained. 2,3,4,6-Tetra-O-benzyl-α-D-galactopyranosyl chloride failed to react with any of the nucleophiles.Methanolysis reactions of the phosphonium salts were too slow to be practical and were not studied extensively. Methanolyses of several quaternary ammonium salts in various solvents were not completely stereospecific, but gave good yields of methyl 2,3,4,6-tetra-O-benzyl-α-D-galactopyranoside. Attempted reactions of benzyl 2-O-benzoyl-4,6-O-benzylidene-β-D-galactopyranoside with quaternary ammonium salts derived from 2,3,4,6-tetra-O-benzyl-α-D-galactopyranosyl bromide failed to produce the corresponding derivative of 3-O-(α-D-galactopyranosyl)-D-galactose.  相似文献   

13.
α-d-Glucopyranosyl α-d-xylopyranoside has been synthesized in 49% yield by treatment of 2,3,4-tri-O-benzyl-α-d-xylopyranosyl bromide with 2,3,4,6-tetra-O-acetyl-d-glucopyranose in nitromethane-benzene with mercuric cyanide and bromide, followed by catalytic hydrogenolysis and O-deacetylation. Condensation with 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide in acetonitrile-dichloromethane with mercuric cyanide, followed by catalytic hydrogenolysis and O-deacetylation, gave α-d-glucopyranosyl α-d-mannopyranoside and β-d-glucopyranosyl β-d-mannopyranoside in 44 and 25% yield, respectively. The mixture was resolved by column chromatography of the fully acetylated derivatives. Selective acetylation of the di-O-benzylidene derivative of trehalose with N-acetylimidazole, followed by oxidation with dimethyl sulfoxide-acetic anhydride at C-3 and stereoselective reduction gave, after removal of the protecting groups, α-d-allopyranosyl α-d-glucopyranoside in 20% overall yield. The structure of the compounds was confirmed by 1H- and 13C-n.m.r., and mass spectrometry. α-d-Glucopyranosyl α-d-xylopyranoside and α-d-allopyranosyl α-d-glucopyranoside are less efficient substrates than trehalose for cockchafer trehalase, but α-d-glucopyranosyl α-d-mannopyranoside is a competitive inhibitor of the enzyme.  相似文献   

14.
The title compound, used in the synthesis of glycopeptides and as a reference substance in the structural elucidation of glycoproteins, was synthesized by condensation of 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide with 2-acetamido-4,6-O-benzylidene-α-d-glucopyranosyl azide, followed by removal of the benzylidene group to give the disaccharide azide 6 and acetylation. The resulting fully acetylated disaccharide azide 7 was also obtained by treatment of the known 2-acetamido-1,4,6-tri-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl)-α-d-glucopyranose with hydrogen chloride and then with silver azide. The azide 7 was reduced in presence of platinum oxide (Adams' catalyst), and the resulting amine was condensed with 1-benzyl N-benzyloxycarbonyl-l-aspartate in the presence of N,N′-dicyclocarbodiimide. The removal of the protective group was accomplished by hydrogenolysis and O-deacetylation. In a second route, the disaccharide azide 6 was reduced and then condensed with 1-benzyl N-benzyloxycarbonyl-l-aspartate, and the resulting product hydrogenolyzed.  相似文献   

15.
2,3,4,6-Tetra-O-acetyl-β-d-mannopyranosyl chloride (2) was obtained in 70% yield by the action of lithium chloride on 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide (1) in hexamethylphosphoric triamide. p-Nitrobenzenethiol reacted with 1 and 2 as well as with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide (9) or its β-d-chloro analog (10), giving exclusively and in good yield the corresponding p-nitrophenyl 1-thioglycosides of inverted anomeric configuration. The 1,2-cis-d-manno and -glucop-nitrophenylglycosides were likewise prepared. α-d-Glucopyranosyl 1-thio-α-d-glucopyranoside was similarly obtained by the action of the sodium salt of 1-thio-α-d-glucopyranose on the β-chloride 10 in hexamethylphosphoric triamide, or by treatment of 10 with sodium sulfide, with subsequent deacetylation. Analogous procedures allowed the preparation of β-d-mannopyranosyl 1-thio-β-d-mann opyranoside, the corresponding α,β anomer and α-d-glucopyranosyl 1-thio-α-d-mannopyranoside, starting from bromide 1, 1-thio-α-d-mannopyranose (8),and chloride 10, respectively. When acetone was used as solvent, the reaction between 1 and 8 led instead to the α,α anomer. The thio disaccharides that are interglycosidic 4-thio analogs of methyl 4-O-(β-d-galactopyranosyl)-α-d-galactopyranoside, methyl α-cellobioside, and methyl α-maltoside, respectively, were obtained by way of the peracetates of methyl 4-thio-α-d-galactopyranoside and -glucopyranoside by reaction of the corresponding thiolates with tetra-O-acetyl-α-d-galactopyranosyl bromide, bromide 9, or chloride 10, respectively, in hexamethylphosphoric triamide. These 1-thioglycosides, and (1→1)- and (1→4)-thiodisaccharides, were characterized by 1H- and 1 3C-n.m.r. spectroscopy. Correlations were established between the polarity of the sulfur atom and certain proton and carbon chemical-shifts in the 1-thioglycosides in comparison with the O-glycosyl analogs; these correlations permitted in particular the unambigous attribution of anomeric configuration.  相似文献   

16.
Oxidation with the dimethyl sulfoxide-acetic anhydride reagent of methyl 2-O-acetyl-4,6-O-benzylidene-α-d-mannopyranoside, obtained in quantitative yield from the corresponding 4,6-benzylidene acetal by stereoselective opening of a 2,3-orthoester, led in good yield to methyl 2-O-acetyl-4,6-O-benzylidene-α-d-arabino-hexopyranosid-3-ulose, which was reduced with either sodium borohydride or sodium borodeuteride into a methyl 4,6-O-benzylidene-α-d-altropyranoside or its 3-2H derivative. A sequence involving a C-6 halogenation-dehydrohalogenation followed by catalytic hydrogenation of the resulting methyl 6-deoxy-α-d-arabino-hex-5-enopyranoside gave methyl 6-deoxy-β-l-galactopyranoside (methyl β-l-fucopyranoside) and then α-l-fucose, with an overall yield of 24% with respect to the starting methyl α-d-mannopyranoside.  相似文献   

17.
《Carbohydrate research》1985,144(1):77-86
3-Amino-3-deoxy-α-d-mannopyranosyl α-d-mannopyranoside was synthesized from known 2-O-benzyl-4,6-O-benzylidene-α-d-altropyranosyl 3-O-benzyl-4,6-O-benzylidene-α-d-glucopyranoside, which is available in four steps from commercial α,α-trehalose. The 3,2′-ditriflate of the blocked disaccharide was first treated with sodium azide under phase-transfer conditions, which effected regioselective displacement of the 3-triflyloxy group, and subsequent reaction with sodium benzoate in N,N-dimethylformamide displaced the 2′-triflyloxy group. The blocked, 3-azido-2′-O-benzoyl derivative of α-d-mannopyranosyl α-d-mannopyranoside so obtained was conventionally debenzoylated and debenzylidenated, and subsequent, palladium-catalyzed transfer hydrogenation with formic acid effected reduction of the azido group and cleavage of the benzyl protecting groups, to give the title disaccharide in 13% over-all yield.  相似文献   

18.
The condensation of 2,3,4,6-tetra-O-benzyl-D-glucopyranosyl bromide and 2,3,4,6-tetra-O-benzyl-D-mannopyranosyl chloride with benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside (1), under Koenigs-Knorr conditions, gave the fully benzylated derivatives of benzyl 2-acetamido-2-deoxy-4-O-α-D-glucopyranosyl-α-D-glucopyranoside, benzyl 2-acetamido-2-deoxy-4-O-β-D-glucopyranosyl-α-D-glucopyranoside, and benzyl 2-acetamido-2-deoxy-4-O-α-D-mannopyranosyl-α-D-glucopyranoside. Three further compounds, namely, benzyl 2-acetamido-3-O-benzyl-2-deoxy-6-O-(2,3,4,6-tetra-O-benzyl-D-glucopyranosyl)-α-D-glucopyranoside, benzyl 2-acetamido-3-O-benzyl-2-deoxy-6-O-(2,3,4,6-tetra-O-benzyl-D)-mannopyranosyl)-α-D-glucopyranoside, and benzyl 2-acetamido-3-O-benzyl-2-deoxy-4,6-di-O-(2,3,4,6-tetra-O-benzyl-D-mannopyranosyl)-α-D-glucopyranoside, were formed by reaction of the respective glycosyl halide with benzyl 2-acetamido-3-O-benzyl-2-deoxy-α-D-glucopyranoside present as contaminant in 1.  相似文献   

19.
The Halide ion-catalysed reaction of benzyl exo-2,3-O-benzylidene-α-l-rhamnopyranoside with tetra-O-benzyl-α-d-galactopyranosyl bromide and hydrogenolysis of the exo-benzylidene group of the product 2 gave benzyl 3-O-benzyl-4-O-(2,3,4,6-tetra-O-benzyl-α-d-galactopyranosyl)-α-l-rhamnopyranoside (6). Compound 2 was converted into 4-O-α-d-galactopyranosyl-l-rhamnose. The reaction of 6 with tetra-O-acetyl-α-d-glucopyranosyl bromide and removal of the protecting groups from the product gave 4-O-α-d-galactopyranosyl-2-O-β-d-glucopyranosyl-l-rhamnose.  相似文献   

20.
Methyl and benzyl 3-O-β-d-xylopyranosyl-α-d-mannopyranoside were prepared by way of d-xylosylation (Koenigs-Knorr) of methyl and benzyl 4,6-O-benzylidene-α-d-mannopyranoside (1 and 17). Analogous 2-O-β-d-xylopyranosyl-α-d-mannopyranosides could not be prepared efficiently by this procedure. However, methyl and benzyl 3-O-acetyl-4,6-O-benzylidene-α-d-mannopyranoside, prepared by limited acetylation of 1 and 17, respectively, could be d-xylosylated by the same method, and afforded, after removal of protective groups, methyl and benzyl 2-O-β-d-xylopyranosyl-α-d-mannopyranoside. Hydrogenolysis of benzyl 2-O- and 3-O-β-d-xylopyranosyl-α-d-mannopyranoside yielded the corresponding, reducing disaccharides. In addition to these disaccharides, disaccharides containing an α-d-xylopyranosyl group, and trisaccharides having d-xylopyranosyl groups at both O-2 and O-3 were obtained as minor products.  相似文献   

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