Syntheses stereoselectives de 1-thioglycosides

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 3}C-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.     

Observations on the possible application of glycosyl disulphides,sulphenic esters,and sulphones in the synthesis of glycosides

Partial desulphuration of tetra-O-acetyl-β-d-glucopyranosyl phenyl disulphide with a phosphine derivative gave 40% of phenyl 2,3,4,6-tetra-O-acetyl-1-thio-α-d- glucopyranoside and a similar proportion of β-d-glucopyranosyl 1-thio-α-d-glucopyranoside octa-acetate, showing that this procedure is of limited value in α-d-thio-glucoside synthesis. Similar treatment of allyl tetra-O-acetyl-,β-d-glucopyranosyl sulphoxide caused abstraction of oxygen, rather than of sulphur, from the derived allyl glucosylsulphenate. The phenylsulphonyl group was not readily displaced from β-d-glucopyranosyl phenyl sulphone, except intramolecularly, nor could it be displaced from the tetrabenzyl ether. Elimination of benzyl alcohol from this compound afforded a new 1-(phenylsulphonyl)glycal derivative.     

The chemistry of some 1-mercury(II)thio-d-glucose compounds; a new synthesis of 1-thio sugars

Treatment of tetra-O-acetyl-β-d-glucopyranosyl N,N-dimethyldithiocarbamate (1) with phenylmercury(II) acetate gives tetra-O-acetyl-1-phenylmercury(II)thio-β-d-glucopyranose (3), which can also be made in high yield from other dithiocarbamates, from tetra-O-acetyl-1-thio-β-d-glucopyranose, and from its S-acetyl derivative. The p-diethylamino derivative (7) of compound 3 displays significantly different properties and is readily convertible into bis(tetra-O-acetyl-1-thio-β-d-glucopyranosyl)mercury(II) (8), which is also obtainable by treatment of tetra-O-acetyl-1-thio-β-d-glucopyranose with mercury(II) acetate. Aspects of the chemistry of compounds 3, 7, and 8 are reported; demercuration of 3 affords a convenient synthesis of 2,3,4,6-tetra-O-acetyl-1-thio-β-d-glucose.     

Practical synthesis of O-β-d-mannopyranosyl-, O-α-d-mannopyranosyl-, and O-β-d-glucopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→3)-d-galactoses

The koenigs-Knorr glycosylation of 4,6-O-ethylidene-1,2-O-isopropylidene-3-O-(2,3-O-isopropylidene-α-l-rhamnopyranosyl)-α-d-galactopyranose (3) by 4,6-di-O-acetyl-2,3-O-carbonyl-α-d-mannopyranosyl bromide (10), as well as Helferich glycosylations of 3 by tetra-O-acetyl-α-d-mannopyranosyl and -α-d-glucopyranosyl bromides, proceeded smoothly to give high yields of trisaccharide derivatives (12, 16, and 17). An efficient procedure for the transformation of 12, 16, and 17 into the α-deca-acetates of the respective trisaccharides has been developed. Zemplén de-acetylation then afforded the title trisaccharides in yields of 53, 52, and 62 %, respectively, from 3. A new route to 1,4,6-tri-O-acetyl-2,3-O-carbonyl-α-d-mannopyranose is suggested.     

Thiodisaccharides with galactofuranose or arabinofuranose as terminal units: Synthesis and inhibitory activity of an exo β-d-galactofuranosidase

Thiodisaccharides having β-d-Galf or α-l-Araf units as non-reducing end have been synthesized by the SnCl₄- or MoO₂Cl₂-promoted thioglycosylation of per-O-benzoyl-d-galactofuranose (1), its 1-O-acetyl analogue 4, or per-O-acetyl-α-l-arabinofuranose (16) with 6-thioglucose or 6-thiogalactose derivatives. After convenient removal of the protecting groups, the free thiodisaccharides having the basic structure β-d-Galf(1→6)-6-thio-α-d-Glcp-OMe (5) or β-d-Galf(1→6)-6-thio-α-d-Galp-OMe (15) were obtained. The respective α-l-Araf analogues 18 and 20 were prepared similarly from 16. Alternatively, β-d-Galf(1→4)-4-thio-3-deoxy-α-l-Xylp-OiPr was synthesized by Michael addition to a sugar enone of 1-thio-β-d-Galf derivative, generated in situ from the glycosyl isothiourea derivative of 1. The free S-linked disaccharides were evaluated as inhibitors of the β-galactofuranosidase from Penicillium fellutanum, being 15 and 20 the more active inhibitors against this enzyme.     

Analysis of permethylated hexopyranosyl-2-acetamido-2-deoxyhexitols by g.l.c.-m.s.

The major product obtained on acetonation of d-mannose with a 2-molar excess of isopropenyl methyl (or ethyl) ether is 4,6-O-isopropylidene-α-d-mannopyranose (3a), the product of kinetic acetonation: a larger excess of the reagent leads, to the 2,3:4,6-diisopropylidene acetal (6). The course of the reaction and side-products formed were examined in detail. The 1,2,3-triacetate of 3a was deacetonated to give α-d-mannopyranose 1,2,3-triacetate; similar reactions were performed on the β anomers. The 1-acetate of the diacetal 6 could be selectively deacetonated to give 1-O-acetyl-2,3-O-isopropylidene-α-d-mannopyranose. The reactions provide access to protected derivatives of d-mannose, and partially acylated derivatives, having modes of substitution different from those obtainable by classical acetonation procedures conducted under conditions of thermodynamic control.     

Galactan sulfate from the test of tunicates

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.     

Synthesis of purine and pyrimidine 2′-deoxynucleosides from a 1,2-dithio sugar precursor

9-(2-S-Ethyl-2-thio- and α-D-mannofuranosyl)adenine (8α and 8β) were synthesized from ethyl 3,5,6-tri-O-acetyl-2-S-ethyl-1,2-dithio-α-D-mannofuranoside (1) by bromination followed by coupling of the resultant bromide (2) with 6-benzamido-(chloromercuri)purine. The 2-chloro analogues (10α and 10β) of 8α and 8β were obtained by way of a fusion reaction between 1,3,5,6-tetra-O-acetyl-2-S- ethyl-2-thio-α-D-mannofuranose (5) and 2,6-dichloropurine. Fusion of the bromide 2 with 2,4-bis(trimethylsilyloxy)pyrimidine and its 5-methyl derivative led to 1-(2-S- ethyl-2-thio-β-D-mannofuranosyl)uracil (16) and its thymine analogue (15). The action of Raney nickel led to rapid dechlorination of 10α and 10β, and all of the 2′-thio-nucleosides underwent desulfurization to give the corresponding 2′-deoxynucleosides. Sequential periodate oxidation-borohydride reduction converted the hexofuranosyl nucleosides into their pentofuranosyl analogues. Thus prepared were 9-(2-deoxy-α-and β-D-arabino-hexofuranosyl)adenine (11α and 11β) and their 2-deoxy-D-threo-pentofuranosyl counterparts (6α and 2′-deoxy-3′-epiadenosine, 6β), and 1-(2-deoxy- β-D-arabino-hexofuranosyl)-thymine (17) and -uracil (18) and their 2-deoxy-D-threo-pentofuranosyl counterparts (3′-epithymidine, 21, and 2′-deoxy-3′-epiuridine, 20). Detailed n.m.r.-spectral correlations are described for the series, and various derivatives of the nucleosides are reported.     

Syntheses of p-aminophenyl α-d-talopyranoside and 1-thio α-d-talopyranoside as analogs of glycosidase substrates

p-Nitrophenyl and p-aminophenyl α-d-talopyranoside and 1-thio-α-d-talopyranosides were prepared for studies on specificity of glycosidases. Reaction of α-d-talopyranose pentaacetate with p-nitrophenol gave exclusively p-nitrophenyl 2,3,4,6-tetra-O-acetyl-α-d-talopyranoside (2) in 63% yield. A similar reaction with p-nitrobenzenethiol afforded the 1-thio analog (3) of 2 in 41.8% yield; the p-nitrophenyl 2,3,4,6-tetra-O-acetyl-1-thio-β-d-talopyranoside (6) was also obtained in low yield (6.7%). The two α-d-talosides 2 and 3 were catalytically deacetylated in near-quantitative yields by methanolic sodium methoxide. The p-nitrophenyl α-d-talopyranoside (4) and 1-thio-α-d-talopyranoside (5) were reduced with palladium on barium sulfate catalyst to the corresponding p-aminophenyl talosides. The acetylated p-nitrophenyl d-talosides 2, 3, and 6 were determined, from their 250-MHz n.m.r. spectra, to exist in the ⁴C₁ (d) conformation in chloroform solution.     

Thio and seleno sugar esters of dialkylarsinous acids

The syntheses of 2,3,4,6-tetra-O-acetyl-1-S-dimethylarsino-1-thio-β-D-glucopyranose (3), 2,3,4,6-tetra-O-acetyl-1-Se-dimethylarsino-1-seleno-β-D-glucopyranose (4), 1-S-dimethylarsino-1-thio-β-D-glucopyranose (5), and -1-Se-dimethylarsino-1-seleno-β-D-glucopyranose (7) are described. The n.m.r., Raman, and mass-spectral properties of the compounds are given. 3-O-Diethylarsino-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose has also been prepared, but characterized only by n.m.r. spectroscopy.     

Syntheses of p-aminophenyl 1-thio-α- and -β-d-idopyranosides as analogs of glycosidase substrates

The p-nitrophenyl and p-aminophenyl 1-thio-α- and -β-d-idopyranosides were synthesized for use in structure-activity studies of glycosidases. Zinc chloride-catalyzed fusion of α-d-idopyranose pentaacetate with p-nitrobenzenethiol gave p-nitrophenyl 2,3,4,6-tetra-O-acetyl-1-thio-α-d-idopyranoside as an amorphous glass in 67% yield, and the crystalline β anomer in 13% yield. Deacetylation with catalytic amounts of sodium methoxide in methanol, followed by hydrogenation under pressure over palladium-on-barium sulfate catalyst, afforded p-aminophenyl 1-thio-α- and -β-d-idopyranosides.     

Selective formation of glycosidic linkages of N-unsubstituted 4-hydroxyquinolin-2-(1H)-ones

A comparative study for selective glucosylation of N-unsubstituted 4-hydroxyquinolin-2(1H)-ones into 4-(tetra-O-acetyl-β-d-glucopyranosyloxy)quinolin-2(1H)-ones is reported. Four glycosyl donors including tetra-O-acetyl-α-d-glucopyranosyl bromide, β-d-glucose pentaacetate, glucose tetraacetate and tetra-O-acetyl-α-d-glucopyranosyl trichloroacetimidate were tested, along with different promoters and reaction conditions. The best results were obtained with tetra-O-acetyl-α-d-glucopyranosyl bromide with Cs₂CO₃ in CH₃CN. In some cases the 4-O-glucosylation of the quinolinone ring was accompanied by 2-O-glucosylation yielding the corresponding 2,4-bis(tetra-O-acetyl-β-d-glucopyranosyloxy)quinoline. Next, 4-(tetra-O-acetyl-β-d-glucopyranosyloxy)quinolin-2(1H)-ones were deacetylated into 4-(β-d-glucopyranosyloxy)quinolin-2(1H)-ones with Et₃N in MeOH. In some instances the deacetylation was accompanied by the sugar-aglycone bond cleavage. Structure elucidation, complete assignment of proton and carbon resonances as well as assignment of anomeric configuration for all the products under investigation were performed by 1D and 2D NMR spectroscopy.     

Synthesis of 4-O-α-d-galactopyranosyl-l-rhamnose and 4-O-α-d-galactopyranosyl-2-O-β-glucopyranosyl-l-rhamnose using dioxolane-type benzylidene acetals as temporary protecting-groups

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.     

Aufbau von oligosacchariden mit glycosylfluoriden unter lewissäure-katalyse

Glycosylation of 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose (6), as well as its 6-trimethylsilyl ether 7 with 2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl fluoride (5) was achieved stereospecifically in a mild and fast manner in the presence of Lewis acids like, e.g., titanium tetrafluoride, to give the β-(1→6)-linked disaccharide derivative 1. By use of 2,3,4,6-tetra-O-benzyl-β-d-glucopyranosyl fluoride (8) or its α anomer 10 and titanium tetrafluoride in acetonitrile with 6 or 7, a fast reaction proceeds preponderantly to yield 1,2:3,4-di-O-isopropylidene 6-O-(2,3,4,6-tetra-O-benzyl-β-d-glucopyranosyl)-α-d-galactopyranose (2). In ether, however, mainly the α-(1→6) anomer was formed. These model systems were used to elucidate the limiting conditions for this procedure, and mechanistic conceptions are discussed. By glycosylation at O-4 of 1,6:2,3-dianhydro-β-d-mannopyranose (11) with the perbenzylated α-fluoride 10 both the α- and the β-d-(1→4) disaccharide derivatives 12 and 14 were obtained, but 5 gave exclusively the β-d-(1→4) compound 16. Opening of the anhydro rings of 12 led to the synthesis of N-acetyl-maltosamine (22). 1,6-Anhydro-2-azido-4-O-benzyl-2-deoxy-β-d-glucopyranose was glycosylated with methyl (2,3,4-tri-O-acetyl-β-d-galactopyranosyl fluoride)uronate under titanium tetrafluoride catalysis to give the β-d-(1→3)-linked disaccharide 16, subsequently transformed into 29.     

Synthesis of N-[2-O-(2-acetamido-2,3-dideoxy-5-thio-d-glucopyranose-3-yl)-d-lactoyl]-l-alanyl-d-isoglutamine

N-[2-O-(2-Acetamido-2,3-dideoxy-5-thio-d-glucopyranose-3-yl)-d-lactoyl]-l-alanyl-d-isoglutamine, in which the ring-oxygen atom of the sugar moiety in N-acetylmuramoyl-l-alanyl-d-isoglutamine (MDP) has been replaced by sulfur, was synthesized from 2-acetamido-2-deoxy-5-thio-α-d-glucopyranose (1). O-Deacetylation of the acetylated acetal, derived from the methyl α-glycoside of 1 by 4,6-O-isopropylidenation and subsequent acetylation, gave methyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-5-thio-α-d-glucopyranoside (4). Condensation of 4 with l-2-chloropropanoic acid, and subsequent esterification, afforded the corresponding ester, which was converted, viaO-deisopropylidenation, acetylation, and acetolysis, into 2-acetamido-1,4,6-tri-O-acetyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-5-thio-α-d-glucopyranose (12). Coupling of the acid, formed from 12 by hydrolysis, with the methyl ester of l-alanyl-d-isoglutamine, and de-esterification, yielded the title compound.     

Addition of halogenoazides to glycals

Addition of chloroazide to 3,4,6-tri-O-acetyl-1,5-anhydro-2-deoxy-d-lyxo- (1) and -d-arabino-hex-1-enitol (2) under u.v. irradiation proceeds regio- and stereo-selectively yielding mainly O-acetyl derivatives of 2-azido-2-deoxy-d-galactopyranose and -d-glucopyranose, respectively. 3,4,6-Tri-O-acetyl-2-chloro-2-deoxy-α-d-galactopyranosyl azide and 3,4,6-tri-O-acetyl-2-azido-2-deoxy-α-d-talopyranose (from 1), and 1,3,4,6-tetra-O-acetyl-2-chloro-2-deoxy-α-d-glucopyranosyl azide and 1,3,4,6-tetra-O-acetyl-2-azido-2-deoxy-α-d-mannopyranose (from 2) are byproducts. 1,5-Anhydro-3,4,6-tri-O-benzyl-2-deoxy-d-lyxo- and -d-arabino-hex-1-enitol reacted more rapidly with chloroazide, to give, under irradiation, derivatives of 2-azido-2-deoxy-d-galactose and -d-glucose, respectively. However, reaction in the dark gave mainly O-benzyl derivatives of 2-chloro-2-deoxy-α-d-galacto- and -α-d-glucopyranosyl azide. The difference between the products obtained may depend on the existence of two parallel processes, one radical (under irradiation), and the other ionic (reaction in the dark).     

Synthese der T-antigenen trisaccharide O-β-d-galactopyranosyl-(1→3)-O-(2-acetamido-2-desoxy-α-d-galactopyranosyl)-(1→6)-d-galactopyranose und O-β-d-galactopyranosyl-(1→3)-O-(2-acetamido-2-desoxy-α-d-galactopyranosyl)-(1→6)-d-glucopyranose und deren anknüpfung an proteine

The synthesis of the trisaccharides O-β-d-galactopyranosyl-(1→3)-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-(1→6)-d-galactopyranose (15) and O-β-d-galactopyranosyl-(1→3)-O-(2-acetamido-2-deoxy-α-d-galactopyranosyl)-(1→6)-d-glucopyranose (27) is described and the synthesis of α-d-glycosides by reaction of 3,4,6-tri-O-acetyl-2-azido-2-deoxy-β-d-galactopyranosyl chloride with highly reactive hydroxyl groups is discussed. The trisaccharide 27 was coupled with serum albumin by formation of an imine intermediate and reduced to an amine, to yield a synthetic T-antigen. A similar coupling of 15 was unsuccessful.     

Ring-opening reactions of sucrose epoxides: Synthesis of 4′-derivatives of sucrose

The 2,1′-O-isopropylidene derivative (1) of 3-O-acetyl-4,6-O-isopropylidene-α-d-glucopyranosyl 6-O-acetyl-3,4-anhydro-β-d-lyxo-hexulofuranoside and 2,3,4-tri-O-acetyl-6-O-trityl-α-d-glucopyranosyl 3,4-anhydro-1,6-di-O-trityl-β-d-lyxo-hexulofuranoside have been synthesised and 1 has been converted into 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,6-di-O-acetyl-3,4-anhydro-β-d-lyxo-hexulofuranoside (2). The S_N2 reactions of 2 with azide and chloride nucleophiles gave the corresponding 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-azido-4-deoxy-β-d-fructofuranoside (6) and 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-chloro-4-deoxy-β-d-fructofuranoside (8), respectively. The azide 6 was catalytically hydrogenated and the resulting amine was isolated as 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 4-acetamido-1,3,6-tri-O-acetyl-4-deoxy-β-d-fructofuranoside. Treatment of 5 with hydrogen bromide in glacial acetic acid followed by conventional acetylation gave 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-bromo-4-deoxy-β-d-fructofuranoside. Similar S_N2 reactions with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,6-di-O-acetyl-3,4-anhydro-β-d-ribo-hexulofuranoside (12) resulted in a number of 4′-derivatives of α-d-glucopyranosyl β-d-sorbofuranoside. The regiospecific nucleophilic substitution at position 4′ in 2 and 12 has been explained on the basis of steric and polar factors.     

Glycosidases. Ligands for affinity chromotagraphy: II. Syntheses of p-aminophenyl 1-thio-L-fucopyranosides

Syntheses of p-aminophenyl 1-thio-α-L- and β-L-fucopyranosides are described. 1,2,3,4-Tetra-O-acetyl-α-L-fucopyranose, on heating with p-nitrothiophenol in the presence of p-toluenesulfonic acid under diminished pressure, gave a mixture of p-nitrophenyl 2,3,4-tri-O-acetyl-1-thio-α- and β-L-fucopyranosides, which was separated by chromatography on silica gel. When the reaction was carried out in the presence of zinc chloride at atmospheric pressure, the β-anomer was the exclusive product. Deacetylation of the aryl α-L- and α-L-thiofucopyranosides with sodium methoxide, followed by catalytic hydrogenation in the presence of palladium on barium sulfate, afforded the respective aminophenyl 1-thiofucopyranosides. The aryl thiofucopyranosides thus synthesized were tested for their inhibitory activity toward clam α-L-fucosidase. The p-aminophenyl 1-thio α-L-fucopyranoside showed a competitive-type inhibition, with a K_i of 0.71mM.     

The stepwise synthesis of a methyl β-xylotetraoside related to branched xylans

3,4-Di-O-acetyl-2-O-benzyl-α-d-xylopyranosyl bromide (1) reacts with methyl 2,3-anhydro-α-d-ribopyranoside (2) to afford, in high yield, methyl 2,3-anhydro-4-O- (3,4-di-O-acetyl-2-O-benzyl-β-d-xylopyranosyl)-β-d-ribopyranoside (3). Deacetylation of 3 gave 4, which reacted with 2,3,4-tri-O-acetyl-α-d-xylopyranosyl bromide to give the branched tetrasaccharide derivative 5, which, in turn, was converted by a series or conventional reactions into methyl 4-O-[3,4-di-O-(β-d-xylopyranosyl)-β-d- xylopyranosyl]-β-d-xylopyranoside. The reaction of 1 with its hydrolysis product gave 3,4-di-O-acetyl-2-O-benzyl-α-d-xylopyranosyl 3,4-di-O-acetyl-2-O-benzyl-β-d-xylopyranoside, which was also isolated after the reaction of 1 with 2.