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1.
A facile approach towards the synthesis of 4-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-2-acetamido-2-deoxy-beta-D-glucopyra nos ide, 2-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D-glucop yra nosyl)- (1----6)-2-acetamido-2-deoxy-alpha-D-galactopyranoside, 4-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D-glucop yra nosyl)- (1----6)-alpha-D-mannopyranoside, and 4-nitrophenyl O-alpha-L-fucopyranosyl-(1----3)-O-(2-acetamido-2-deoxy-beta-D-glucop yra nosyl)-(1----6)-beta-D-galactopyranoside has been accomplished through the development and use of methyl 3,4-O-isopropylidene-2-O-(4-methoxybenzyl)-1-thio-beta-L-fucopyranoside as the glycosyl donor. 相似文献
2.
The sulfated pentasaccharide benzyl O-(3-O-sulfo-beta-D-galactopyranosyl)-(1-->3)-O-[(alpha-L-fucopyranosyl)-(1-->4)]-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1-->3)-O-(beta-D-galactopyranosyl)-(1-->4)-O-beta-D-glucopyranoside sodium salt was synthesized using a chemo-enzymatic approach. Lacto-N-tetraose, obtained from two disaccharides [4-methoxybenzyl O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-(1-->3)-4,6-O-benzylidene-2-deoxy-2-phtalimido-beta-D-glucopyranoside and benzyl 2,6-di-O-acetyl-beta-D-galactopyranosyl-(1-->4)-2,3,6-tri-O-acetyl-beta-D-glucopyranoside], was regioselectively sulfated at the 3 OH position of the terminal galactose using the stannylene procedure. The fucosylation of the sulfated tetrasaccharide was performed using soluble or immobilized fucosyltransferase FucT-III to give the title compound. 相似文献
3.
The synthesis is reported of methyl 3-O-(4-O-beta-D-galactopyranosyl-alpha-D- glucopyranosyl)-alpha-L-rhamnopyranoside (1), methyl 2-O-alpha-D-glucopyranosyl-4-O-beta-D-glucopyranosyl-beta-D- galactopyranoside (3), methyl 3-O-(4-O-beta-D-galactopyranosyl-alpha-D-glucopyranosyl)-alpha-L- rhamnopyranoside 3"-(sn-glycer-3-yl sodium phosphate) (2), and methyl 2-O-alpha-D-glucopyranosyl-4-O-beta-D- glucopyranosyl-beta-D-galactopyranoside 3-(sn-glycer-3-yl sodium phosphate) (4), which are trisaccharide methyl glycosides related to fragments of the capsular polysaccharide of Streptococcus pneumoniae type 18C ([----4)-beta-D- Glcp-(1----4)-[alpha-D-Glcp-(1----2)]-[Glycerol-(1-P----3)]-beta-D-Galp - (1----4)-alpha-D-Glcp-(1----3)-alpha-L-Rhap-(1----]n). Ethyl 4-O-acetyl-2,3,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside (10) was coupled with benzyl 2,4-di-O-benzyl-alpha-L-rhamnopyranoside (6). Deacetylation of the product, followed by condensation with 2,4,6-tri-O-acetyl-3-O-allyl-alpha-D-galactopyranosyl trichloroacetimidate (18), gave benzyl 2,4-di-O-benzyl-3-O-[2,3,6-tri-O- benzyl-4-O-(2,4,6-tri-O-acetyl-3-O-allyl-beta-D-galactopyranosyl)-alpha- D- glucopyranosyl]-alpha-L-rhamnopyranoside (19). Acetolysis of 19, followed by methylation, deallylation (----22), and further deprotection afforded 1. Condensation of methyl 2,4-di-O-benzyl-3-O-[2,3,6-tri-O-benzyl-4-O-(2,4,6-tri- O-acetyl-beta-D-galactopyranosyl)-alpha-D-glucopyranosyl]-alpha-L- rhamnopyranoside (22) with 1,2-di-O-benzyl-sn-glycerol 3-(triethyl-ammonium phosphonate) (24), followed by oxidation and deprotection, yielded 2. Condensation of ethyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-glucopyranoside (27) with methyl 3-O-allyl-4,6-O-benzylidene-beta-D-galactopyranoside (28), selective benzylidene ring-opening of the product, coupling with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl trichloroacetimidate (31), and deallylation afforded methyl 6-O-benzyl-4-O-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-2-O- (2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-beta-D-galactopyranoside (33). Deprotection of 33 gave 3, and condensation of 33 with 24, followed by oxidation and deprotection, gave 4. 相似文献
4.
Novel, structurally modified potential mimics of the second messenger D-myo-inositol 1,4,5-trisphosphate, based on the biologically active regioisomer D-myo-inositol 1,4,6-trisphosphate, were synthesised. DL-5-O-Benzyl-1,4,6-tri-O-p-methoxybenzyl-myo-inositol was the key intermediate for the preparation of the following compounds: DL-3-deoxy-, DL-3-deoxy-2-O-methyl-, DL-3-O-(2-hydroxyethyl)-, DL-3-O-(3-hydroxypropyl)- and DL-3-O-(4-hydroxybutyl)-myo-inositol 1,4,6-trisphosphate. DL-1,4,6-Tri-O -allyl-5-O-benzyl-myo-inositol was used to prepare DL-2-O-methyl-myo-inositol 1,4,6-trisphosphate. Deoxy-compounds were prepared by reduction of the corresponding tosylated intermediate using Super Hydride. The hydroxyalkyl groups were introduced at the C-3 of myo-inositol using the corresponding benzyl protected hydroxy alkyl bromide via the cis-2,3-O-dibutylstannylene acetal. Methylation and benzylation at C-2 was accomplished using methyl iodide and benzyl bromide, respectively, in the presence of sodium hydride. Deblocking of p-methoxybenzyl groups was accomplished with TFA in dichloromethane and the allyl groups were removed by isomerisation to the cis-prop-1-enyl derivative, which was hydrolysed under acidic conditions to give the corresponding 1,4,6-triol. The 1,4,6-triols were phosphitylated with the P(III) reagent bis(benzyloxy)(diisopropylamino)phosphine in the presence of 1H-tetrazole then oxidised with 3-chloroperoxybenzoic acid followed by deblocking by hydrogenolysis to give DL-2-O-methyl-, DL-3-O-deoxy-, DL-3-O-deoxy-2-O-methyl-, DL-3-O-(2-hydroxyethyl)-, DL-3-O-(3-hydroxypropyl)- and DL-3-O-(4-hydroxybutyl)-myo-inositol 1,4,6-trisphosphate, respectively. 相似文献
5.
J C Jacquinet 《Carbohydrate research》1990,199(2):153-181
3,4,6-Tri-O-acetyl-D-galactal was transformed into methyl 6-O-acetyl-2-azido-4-O-benzyl-2-deoxy-beta-D-galactopyranoside and its 4-O-acetyl-6-O-benzyl analogue, each of which was glycosylated with activated, O-acetylated derivatives of methyl D-glucopyranosyluronate. The resulting beta-(1----3)-linked disaccharide derivatives were each reductively N-acetylated, hydrogenolysed, O-sulfated, and saponified to afford the disodium salts of methyl 2-acetamido-2-deoxy-3-O-(beta-D-glucopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside and the 6-O-sulfo analogue. D-Galactal was also transformed into activated derivatives of 2-azido-3,6-di-O-benzyl-2-deoxy-D-galactopyranose and their 3,4-di-O-benzyl analogues with various substituents at O-4 and O-6. These glycosyl donors were condensed with 6-O-protected derivatives of methyl 2,3-di-O-benzyl-beta-D-glucopyranoside to give the beta-(1----4)-linked disaccharide derivatives, which were selectively deprotected, then oxidised at C-6 of the gluco unit, reductively N-acetylated, selectively deprotected, O-sulfated at C-4 or C-6 of the galacto unit, and hydrogenolysed to give the disodium salts of methyl 4-O-(2-acetamido-2-deoxy-4-O-sulfo-beta-D-galactopyranosyl)-beta-D- glucopyranosiduronic acid and the 6-O-sulfo analogue. 相似文献
6.
Synthesis of disaccharide fragments of dermatan sulfate 总被引:2,自引:0,他引:2
Condensation of crystalline methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, provided 54% of methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-alpha-L-idopyranosyluronate)-beta-D-galactopyranoside . The use of methyl (2,3,4-tri-O-acetyl-alpha-L-idopyranosyl trichloroacetimidate)uronate as glycosyl donor, in the presence of trimethylsilyl triflate, improved the yield to 68%. Regioselective opening of the benzylidene group with sodium cyanoborohydride followed successively by O-sulfation with the sulfur trioxide-trimethylamine complex, saponification, catalytic hydrogenolysis and selective N-acetylation gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(alpha-L-idopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside. Condensation of methyl 2-azido-4,6-O-benzylidene-2-deoxy-beta-D-galactopyranoside with methyl (2,3,4-tri-O-acetyl-alpha-D-glucopyranosyl bromide)uronate in dichloromethane, in the presence of silver triflate and molecular sieve, gave methyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(methyl 2,3,4-tri-O-acetyl-beta-D-glucopyranosyluronate)-beta-D-galactopryano side in 85% yield. The sequence already described then gave the disodium salt of methyl 2-acetamido-2-deoxy-3-O-(beta-D-glucopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside. 相似文献
7.
Benzylation of methyl 3-O-(2-acetamido-4,6-O-benzylidene-2-deoxy-beta-D- glucopyranosyl)-2,4,6-tri-O-benzyl-beta-D-galactopyranoside with benzyl bromide in N,N-dimethylformamide in the presence of sodium hydride afforded methyl 3-O- (2-acetamido-3-O-benzyl-4,6-O-benzylidene-2-deoxy-beta-D-glucopyranosyl) -2,4,6- tri-O-benzyl-beta-D-galactopyranoside (3). Reductive ring-opening of the benzylidene group of 3 gave methyl 3-O-(2-acetamido-3,6-di-O-benzyl-2-deoxy-beta-D- glucopyranosyl)- 2,4,6-tri-O-benzyl-beta-D-galactopyranoside (4). Cleavage of the 4,6-acetal group of 3 with hot, 80% aqueous acetic acid afforded the diol (5). Compounds 3, 4, and 5 were each subjected to halide ion-catalyzed glycosylation with 2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl bromide to produce the corresponding trisaccharide derivatives, which, on catalytic hydrogenation, furnished the title trisaccharides, respectively. 相似文献
8.
Glycal esters of Kdo derivatives were converted into 2,3-anhydro intermediates, which were transformed into D-glycero-D-talo-oct-2-ulopyranosylonic acid (Ko), as well as 3-O- and 4-O-p-nitrobenzoyl-Ko derivatives. The exo-allyl orthoester derivative, methyl [5,7,8-tri-O-acetyl-4-O-(4-nitrobenzoyl)-2,3-O-[(1-exo-allyloxy)-ethylidene]-D-glycero-beta-D-talo-oct-2-ulopyranos]onate, prepared from the 4-O-pNBz-protected Ko derivative, was elaborated into the alpha-Ko allyl ketoside, the reducing disaccharide alpha-Kdop-(2-->4)-Ko and the disaccharide alpha-Kdop-(2-->4)-Kop-(2-->OAll). Conversely, methyl[4,5,7,8-tetra-O-acetyl-3-O-(4-nitrobenzoyl)-alpha-D-glycero-D-talo-2-octulopyranosyl bromide]onate [Carbohydr. Res., 244 (1993) 69-84], was coupled with a Kdo acceptor to give the disaccharide alpha-Kop-(2-->4)-Kdop-(2-->OAll) after orthoester rearrangement and deprotection. The allyl glycosides were treated with cysteamine and converted into neoglycoproteins. The ligands correspond to inner core units from Acinetobacter haemolyticus and Burkholderia cepacia lipopolysaccharides. 相似文献
9.
2-O-[4-O-(2-Acetamido-2-deoxy-beta-D-mannopyranosyl)-alpha-D- glucopyranosyl]-alpha,beta-L-rhamnopyranose, a structural component of the capsular polysaccharide of Streptococcus pneumoniae type 19F, has been synthesized by sequential glycosylation reactions using the glycosyl acceptor 2,2,2-trichloroethyl 3,4-di-O-benzyl-alpha-L-rhamnopyranoside (prepared from the known 2-O-acetyl-3,4-di-O-benzyl-alpha-L-rhamnopyranosyl chloride), and the glycosyl donors 4-O-acetyl-2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl chloride and 4,6-di-O-acetyl-2-azido-3-O-benzyl-2-deoxy-alpha-D-mannopyranosyl bromide (prepared in seven steps from the known methyl 2-azido-4,6-O-benzylidene-2-deoxy-alpha-D-altropyranoside). The corresponding 8-(methoxycarbonyl)octyl glycoside has also been synthesized, by coupling of 8-(methoxycarbonyl)octyl trifluoromethanesulfonate and the sodium salt of 2-O-[4-O-(2-acetamido-4,6-di-O-acetyl-3-O-benzyl-2-deoxy-beta-D- mannopyranosyl)-2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl]-3,4-di-O- benzyl-alpha,beta-L-rhamnopyranose. 相似文献
10.
Two key synthons for the title pentasaccharide derivative, methyl O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L-idopyranosyluronate)-(1----4)-6-O-acetyl- 2-azido - 3-O- benzyl-2-deoxy-beta-D-glucopyranoside and O-(methyl 2,3-di-O-benzyl-4-O- chloroacetyl-beta-D-glucopyranosyluronate)-(1----4)-3,6-di-O-acetyl-2-az ido-2- deoxy-alpha-D- glucopyranosyl bromide, were prepared from a common starting material, cellobiose. They were coupled to give a tetrasaccharide derivative that underwent O-dechloroacetylation to the corresponding glycosyl acceptor. Its condensation with the known 6-O-acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl bromide afforded a 77% yield of suitably protected pentasaccharide, methyl O-(6-O- acetyl-2-azido-3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)- O- (methyl 2,3- di-O-benzyl-beta-D-glucopyranosyluronate)-(1----4)-O-(3,6-di-O-acetyl-2- azido-2 - deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2-O-benzoyl-3-O-benzyl-alpha-L- idopyranosyluronate)- (1----4)-6-O-acetyl-2-azido-3-O-benzyl-2-deoxy-beta-D-glucopyranoside. Sequential deprotection and sulfation gave the decasodium salt of methyl O-(2- deoxy-2-sulfamido-6-O-sulfo-alpha-D-glucopyranosyl)-(1----4)-O-(be ta-D- glucopyranosyl-uronic acid)-(1----4)-O-(2-deoxy-2-sulfamido-3,6-di-O-sulfo-alpha-D-gluco pyranosyl)- (1----4)-O-(2-O-sulfo-alpha-L-idopyranosyluronic acid)-(1----4)-2-deoxy-2- sulfamido-6-O- sulfo-beta-D-glucopyranoside (3). In a similar way, the trisaccharide derivative, the hexasodium salt of methyl O-(2-deoxy-2-sulfamido-6-O-sulfo-alpha-D- glucopyranosyl)- (1----4)-O-(beta-D-glucopyranosyluronic acid)-(1----4)-2-deoxy-2-sulfamido-3,6- di-O- sulfo-alpha-D-glucopyranoside (4) was synthesized from methyl O-(6-O-acetyl-2- azido- 3,4-di-O-benzyl-2-deoxy-alpha-D-glucopyranosyl)-(1----4)-O-(methyl 2,3-di-O- benzyl-beta- D-glucopyranosyluronate)-3,6-di-O-acetyl-2-azido-2-deoxy-alpha-D- glucopyranoside. The pentasaccharide 3 binds strongly to antithrombin III with an association constant almost equivalent to that of high-affinity heparin, but the trisaccharide 4 appears not to bind. 相似文献
11.
T M Slaghek M J van Vliet A A Maas J P Kamerling J F Vliegenthart 《Carbohydrate research》1989,195(1):75-86
4-Methoxybenzyl 2,4-di-O-benzyl-3-O-[2,4,6-tri-O-benzyl-3-O-(3,4,6-tri-O-benzyl-alpha-D- galactopyranosyl)-alpha-D-glucopyranosyl]-alpha-L-rhamnopyranoside (22), a building block for the alpha-D-Galp-(1----3)-alpha-D-Glcp-(1----3)-alpha-L-Rhap fragment of the capsular polysaccharides of Streptococcus pneumoniae types 6A and 6B [----2)-alpha-D-Galp-(1----3)-alpha-D-Glcp-(1----3)-alpha-L-Rhap-( 1----X)-D- RibOH-(5-P----]n (6A, X = 3; 6B, X = 4) has been synthesised. Ethyl 3-O-allyl-2,4,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside was coupled with 4-methoxybenzyl 2,4-di-O-benzyl-alpha-L-rhamnopyranoside in ether, using methyl triflate as promoter. The resulting alpha-D-Glcp-(1----3)-alpha-L-Rhap derivative was deallylated with KOBut in N,N-dimethylformamide followed by 0.1M HCl in 9:1 acetone-water. The product was coupled with 3,4,6-tri-O-acetyl-2-O-allyl-alpha,beta-D-galactopyranosyl trichloroacetimidate in ether, using trimethylsilyl triflate, to yield 19. Deacetylation, benzylation, and deallylation then gave 22. 相似文献
12.
Condensation of benzyl 2-acetamido-6-O-(2-acetamido-3,4,6-tri-O-acetyl-2- deoxy-3-O-[(R)-1-carboxyethyl]-alpha-D-glucopyranoside (2) and its 4-acetate (4) with L-alanyl-D-isoglutamine benzyl ester via the mixed anhydride method yielded N-(2-O-[benzyl 2-acetamido-6-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D- glucopyranosyl)-2,3-dideoxy-alpha-D-glucopyranosid-3-yl]-(R)-lacto yl)-L- alanyl-D-isoglutamine benzyl ester (5) and its 4-acetate (6), respectively. Condensation by the dicyclohexylcarbodi-imide-N-hydroxysuccinimide method converted 2 into benzyl 2-acetamido-6-O-(2-acetamido-3,4,6-tri-O-acetyl- 2-deoxy-beta-D-glucopyranosyl)-3-O-[(R)-1-carboxyethyl]-2-deoxy-alpha-D- glucopyranoside 1',4-lactone (7). In the presence of activating agents, 7 underwent aminolysis with the dipeptide ester to give 5. Zemplén O-deacetylation of 5 and 6 led to transesterification and alpha----gamma transamidation of the isoglutaminyl residue to give N-(2-O-[benzyl 2-acetamido-6-O-(2- acetamido-2-deoxy-beta-D-glucopyranosyl)-2,3-dideoxy-alpha-D-glucopyr anosid-3- yl]-(R)-lactoyl)-L-alanyl-D-isoglutamine methyl ester (8) and -glutamine methyl ester (9). Treatment of 6 with MgO-methanol caused deacetylation at the GlcNAc residue to give a mixture of N-(2-O-[benzyl 2-acetamido-6-O-(2-acetamido-2- deoxy-beta-D-glucopyranosyl)-4-O-acetyl-2,3-dideoxy-alpha-D-glucopyra nosid-3- yl]-(R)-lactoyl)-L-alanyl-D-isoglutamine methyl ester (11) and -glutamine methyl ester (12). Benzyl or methyl ester-protection of peptidoglycan-related structures is not compatible with any of the reactions requiring alkaline media. Condensation of 2 with L-alanyl-D-isoglutamine tert-butyl ester gave N-(2-O-[benzyl 2-acetamido- 6-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D-glucopyranosyl)-2,3-d ideoxy- alpha-D-glucopyranosid-3-yl]-(R)-lactoyl-L-alanyl-D-isoglutamine tert-butyl ester (16), deacetylation of which, under Zemplén conditions, proceeded without side-reactions to afford N-(2-O-[benzyl 2-acetamido-6-O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-2,3-dideoxy-alpha-D-glucopyranosid-3-yl]-(R)-la cotyl)-L- alanyl-D-isoglutamine tert-butyl ester (17). 相似文献
13.
1,2,5-Tri-O-acetyl-3,6-anhydro-3-thio-D-glucofuranose was synthesised starting from D-glucose and was used as a donor for the glycosidation of 4-cyano- and 4-nitrobenzenethiol. In the latter reaction, besides an anomeric mixture of the 4-nitrophenyl 2,5-di-O-acetyl-3,6-anhydro-1,3-dithio-D-glucofuranosides, the corresponding 2,6-anhydro-1,2-dithio-D-altrofuranosides were also obtained, formed via a rearrangement of the sugar moiety. A similar rearrangement could be observed during the hydrolysis of the glycosidic bond of methyl 3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-alpha-D-glucopyranoside with aqueous trifluoroacetic acid, affording after acetylation besides 1-O-acetyl-3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-alpha-D-glucopyranose (32alpha), 1,1,5-tri-O-acetyl-3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-D-glucose, methyl 3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-3-thio-beta-D-glucopyranoside and 1,5-di-O-acetyl-2,6-anhydro-3-O-(4-nitrobenzoyl)-2-thio-alpha-D-altrofuranose (40). Glycosidation of 4-cyanobenzethiol with 32alpha in the presence of trimethylsilyl triflate as promoter afforded 4-cyanophenyl 3,6-anhydro-2,4-di-O-(4-nitrobenzoyl)-1,3-dithio-beta-D-glucopyranoside as a minor component only, besides 4-cyanophenyl 3,6-anhydro-2-S-(4-cyanophenyl)-4-O-(4-nitrobenzoyl)-1,2,3-trithio-beta-D-glucopyranoside. When boron trifluoride etherate was used as promoter in the reaction of 32alpha with 4-cyano- and 4-nitrobenzenethiol, the corresponding beta-thioglycosides were obtained, while 40 gave under identical conditions the alpha anomers exclusively. All thioglycosides obtained after deacylation were submitted to biological evaluation. Among these glycosides, the 4-cyanophenyl 3,6-thioanhydro-1,3-dithio-D-glucofuranoside possessed the strongest oral antithrombotic effect. 相似文献
14.
The oligosaccharides, methyl 3-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-beta-D-ribofuranosid e, methyl 2-O-beta-D-ribofuranosyl-3-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-beta-D-ribofuranosid e, and methyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2----2)-O-beta-D- ribofuranosyl-(1----2)-beta-D-ribofuranoside were prepared in high purity and good over-all yields. The constitutions of the trisaccharide derivatives correspond to the repeating units of the proposed linear and branched structures of the capsular polysaccharide(s) from Escherichia coli LP 1092. The alpha-KDO-(2----3)-beta-D-Ribf and alpha-KDO-(2----2)-beta-D-Ribf units were synthesized by a modification of the Helferich procedure using methyl (4,5,7,8-tetra-O-acetyl-3-deoxy-alpha-D-manno-2-octulopyranosyl bromide)-onate and appropriate beta-D-ribofuranosyl derivatives. The constitutional and configurational assignments were based on the 250-MHz 1H-n.m.r.-spectra of protected derivatives of the oligosaccharides. 相似文献
15.
I M Morrison 《Carbohydrate research》1974,36(1):45-51
Reaction of the C-2 mercurated methyl hexopyranoside acetates 1–3 with an excess of iodine resulted in nearly quantitative replacement of mercury by iodine with retention and inversion of configuration at C-2. Similar replacement was observed with 2-acetoxymercuri-3,4,6-tri-O-acetyl-2-deoxy-α-d-glucopyranose (4). In the iodinolysis of 2-acetoxymercuri-1,3,4,6-tetra-O-acetyl-2-deoxy-α-d-glucopyranose (5) in methanol, however, replacement at C-2 was accompanied to a considerable extent by solvolysis of the 1-acetoxyl group, and a mixture of 1,2-trans isomers of methyl 3,4,6-tri-O-acetyl-2-deoxy-2-iodo-hexopyranosides having the d-gluco and d-manno configurations was obtained, together with 1,3,4,6-tetra-O-acetyl-2-deoxy-2-iodo-α-d-mannopyranose. 相似文献
16.
N-(Benzyloxycarbonyl)-O-[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galact o-2- nonulopyranosyl)onate]-(2----3)-O-(2,4,6-tri-O-acetyl-beta-D - galactopyranosyl)-(1----3)-O-[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galact o-2- nonulopyranosyl)onate-(2----6)]-O-(2-acetamido-4-O-acetyl-2- deoxy-alpha-D- galactopyranosyl)-(1----3)-L-serine benzyl ester was synthesized by using O-[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5- di-deoxy-D-glycero-alpha-D-galacto-2-nonulopyranosyl)onate]- (2----3)-O-(2,4,6- tri-O-acetyl-beta-D-galactopyranosyl)-(1----3)-O-[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galact o-2- nonulopyranosyl)onate-(2----6)]-4-O-acetyl-2-azido-2-deoxy-a lpha- and -beta-D-galactopyranosyl trichloroacetimidate as a key glycotetraosyl donor which, upon reaction with N-(benzyloxycarbonyl)-L-serine benzyl ester, afforded a 44% yield of a mixture of the alpha- and beta-glycosides in the ratio of 2:5. 相似文献
17.
Glycosylation of methyl 2,4-di-O-benzoyl-alpha-L-rhamnopyranoside with 2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl bromide gave methyl 2,4-di-O-benzoyl-3-O-(2,3,4-tri-O-acetyl-alpha-L-rhamnopyranosyl) -alpha-L-rhamnopyranoside (4) in 93% yield. Conversion of 4 into the corresponding glycosyl bromide was accomplished with dibromomethyl methyl ether. Under Koenigs-Knorr conditions, this bromide reacted with 8-(methoxycarbonyl)octyl 2-O-(2-acetamido-4,6-O-benzylidene-2-deoxy-beta-D-glycopyranosyl)- 3,4-di-O- benzyl-alpha-L-rhamnopyranoside, to provide the protected tetrasaccharide in 91% yield. Removal of blocking groups gave 8-(methoxycarbonyl)octyl O-alpha-L-rhamnopyranosyl-(1---- 3)-O-alpha-L-rhamnopyranosyl-(1---- 3)-O-2-acetamido-2-deoxy-beta-D-glucopyranosyl-(1----2)-alpha-L- rhamnopyranoside. Together with previously synthesized tetrasaccharides of the Shigella flexneri Y O-antigen, this oligosaccharide has been used to study the conformation of O-antigens and to assist in the selection of S. flexneri, variant Y, specific monoclonal antibodies. 相似文献
18.
Glycosylation of methyl (allyl 7,8-O-carbonyl-3-deoxy-alpha-D-manno-2-octulo-pyranosid)o nate with an alpha-(2----4) linked per-O-acetylated KDO-disaccharide bromide derivative under Helferich conditions afforded a 2:1 mixture of the alpha- and beta-linked trisaccharide derivatives in 50% yield. Removal of the protecting groups gave sodium O-[sodium (3-deoxy-alpha-D-manno-2-octulopyranosyl)onate]-(2----4)-O-[ sodium (3-deoxy-alpha- and -beta-D-manno-2-octulopyranosyl)onate]-(2----4)-sodium (allyl 3-deoxy-alpha-D-manno-2-octulopyranosid)onate. Radical copolymerization of the allyl glycosides afforded artificial antigens, suitable for defining antibody specificities directed against the KDO-region of enterobacterial lipopolysaccharides. 相似文献
19.
A fragment of Micrococcus lysodeikticus cell-wall obtained by cetylpyridinium recipitation from the nondialyzable portion of the degradation products of egg-white lysozyme was studied by the periodate oxidation and methylation procedures. The fragment consists of a polysaccharide chain composed of about 40 repeating (1 leads to 4)-O-(2-acetamido-2-deoxy-beta-D-mannopyranosyluronic acid)-(1 leads to 6)-O-(alpha-D-glucopyranosyl) residues with D-glucopyranosyl residues at both ends. The alpha-D-glucopyranose residue at the reducing end is linked to a phosphate group that is also linked to C-6 of a 2-acetamido-3-O-(D-1-carboxyethyl)-2-deoxy-beta-D-glucopyranosyl residue of a peptidoglycan chain composed of four repeating (1 leads to 4)-O-[2-acetamido-3-O-(D-1-carboxyethyl)-2-deoxy-beta-D-glucopyranosyl] residues. The peptidoglycan chain has, as nonreducing group, a 2-acetamido-2-deoxy-beta-D-glucopyranosyl group, and, as reducing residue, a 2-acetamido-3-O-(D-1-carboxytheyl)-2-deoxy-beta-D-glucose residue. 相似文献
20.
Glycosylation of the readily accessible benzyl 2-acetamido-6-O-benzyl-2-deoxy-3-O-[(R)-1-(methoxycarbonyl)ethyl]-alpha- D- glucopyranoside with 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl chloride (2), using the silver triflate method in the absence of a base, afforded 65-70% of the fully protected [beta-D-GlcNPhth-(1----4)-MurNAc] methyl ester derivative 4, the structure of which was ascertained on the basis of 500-MHz 1H-n.m.r. data. 2,2'-Dideoxy-2,2'-diphthalimido-beta,beta-trehalose hexa-acetate was a by-product. Removal of the Phth group from 4, followed by acetylation, yielded 90% of the acetylated 1,6-di-O-benzyl derivative 5, which, on saponification and catalytic hydrogenation, afforded 2-acetamido-4-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-3-O-[(R)-1- carboxyethyl]-2-deoxy-D-glucopyranose. Similarly, 5 was converted into the acetylated methyl ester derivative, which, on selective removal of the methyl ester group, gave benzyl 2-acetamido-4-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-beta-D- glucopyranosyl)-6-O-benzyl-3-O-[(R)-1-carboxyethyl]-2-deoxy-alpha-D- glucopyranoside. An alternative route for the preparation of 2 is described. 相似文献