Allyl Glycosides Research Articles

‘Sugaring’ carbosilane dendrimers via hydrosilylation

Two new pathways to introduce carbohydrate derivatives into dendritic carbosilane structures were explored. Pathway one utilised alcoholysis of a chlorosilane with a protected hydroxyethyl glycoside resulting in Si–O linkages. Pathway two proceeds via a hydrosilylation reaction of a protected allyl glycoside with a carbosilane containing Si–H end groups in the presence of a platinum catalyst, thus leading to Si–C linked structures.

Synthesis of Lewis X trisaccharide analogues in which glucose and rhamnose replace N-acetylglucosamine and fucose, respectively

Two analogues of the Le x trisaccharide, α- l-Fuc p-(1→3)-[β- d-Gal p-(1→4)]- d-Glc p were synthesized as allyl glycosides. In these derivatives either only the N-acetylglucosamine is replaced by glucose or both the N-acetylglucosamine and the fucosyl residue are replaced by glucose and rhamnose, respectively. Our synthetic scheme used armed β-thiophenyl fuco- and rhamnoside glycosyl donors that were prepared anomerically pure from the corresponding α-glycosyl bromides. The protecting groups were chosen to allow access to the fully deprotected trisaccharides without reduction of the allyl glycosidic group. These analogues will be used as soluble antigens in binding experiments with anti-Le x antibodies and can also be conjugated to a carrier protein and used as immunogens. In the course of this synthetic work, we also describe the use of reversed-phase HPLC to purify key protected trisaccharide intermediates prior to their deprotection.

Synthesis of the Blocked Pentasaccharide Derivative Related to the Repeating Unit of the O‐Antigen from Shigella dysenteriae Type 3 in the Form of Its Allyl Glycoside

Starting from d‐galactosamine hydrochloride, d‐galactose and d‐glucose, the tetrasaccharide derivative allyl 2,3,6‐tri‐O‐benzyl‐4‐O‐[methyl (R)‐2‐propanoate]‐β‐d‐glucopyranosyl‐(1→6)‐2,3,4‐tri‐O‐benzyl‐α‐d‐glucopyranosyl‐(1→4)‐2,6‐di‐O‐benzyl‐3‐O‐(3,4,6‐tri‐O‐acetyl‐2‐deoxy‐2‐phthalimido‐β‐d‐galactopyranosyl)‐α‐d‐galactopyranoside has been synthesized via block synthesis strategy, with one of the blocks containing a methyl (R)‐2‐propanoate group. Manipulation of protecting groups of this tetrasaccharide derivative followed by its reaction with a galactofuranoside donor afforded the desired pentasaccharide derivative in the form of its allyl glycoside related to the reapeating unit of Shigella dysenteriae type 3.

Ruthenium Carbenoids as Catalysts for Olefin Metathesis of ω-Alkenyl Glycosides

Publisher Summary Olefin metathesis is a powerful synthetic process that translates, in its most simplified version, into the combination of two alkenes to generate a new double bond among the reacting partners with the evolution of ethylene gas when dealing with terminal alkenes. The procedure can lead to self- and cross-metathesis, ring-closing metathesis, and ring-opening metathesis polymerization. The most widely used catalysts for this process are transition metal carbenoids. Carbohydrate derivatives with allyl ethers, as well as with O- and C-linked allyl glycosides, have been known for a long time, and several of these derivatives are well-established precursors in synthetic carbohydrate chemistry. Obviously, olefin metathesis in its various forms represents a particularly appealing chemical process for the design of small carbohydrate clusters (e.g., dimers), glycomimetics, conformationally restrained oligosaccharides, and perhaps, more importantly, functionalized aglycones with pendant functionalities suitable for further neoglycoconjugate syntheses. This chapter reports some of the applications in which the terminal alkene groups have been introduced in key positions around the ring.

Synthesis of a mannose heptasaccharide existing in baker's yeast, Saccharomyces cerevisiae X2180-1A wild-type strain

A mannose heptasaccharide existing in baker's yeast, Saccharomyces cerevisiae X2180-1A wild-type strain, was effectively synthesized as its allyl glycoside via TMSOTf-promoted condensation of a disaccharide donor 13 with a pentasaccharide acceptor 12, followed by deprotection. The pentasaccharide 12 was constructed by coupling of 2,3,4,6-tetra- O-benzoyl-α- d-mannopyranosyl-(1→3)-2,4,6-tri- O-benzoyl-α- d-mannopyranosyl-(1→2)-3,4,6-tri- O-benzoyl-α- d-mannopyranosyl-(1→2)-3,4,6-tri- O-benzoyl-α- d-mannopyranosyl trichloroacetimidate ( 9) with allyl 6- O-acetyl-3,4-di- O-benzoyl-α- d-mannopyranoside ( 10), followed by deacetylation. The tetrasaccharide 9 was obtained by coupling of 2,3,4,6-tetra- O-benzoyl-α- d-mannopyranosyl-(1→3)-2,4,6-tri- O-benzoyl-α- d-mannopyranosyl trichloroacetimidate ( 5) with allyl 3,4,6-tri-O-benzoyl-α- d-mannopyranosyl-(1→2)-3,4,6-tri- O-benzoyl-α- d-mannopyranoside ( 6), followed by deallylation and trichloroacetimidation. The disaccharides 6 and 13 were readily obtained by known methods.

New Poly(sodium carboxylate)s Based on Saccharides, 1. Synthesis and Characterization of Ionic Allyl Glycoside Polymers

AbstractNew poly(sodium carboxylate)s, containing monosaccharide side groups with ether linkages to the main chain, are presented as substitutes for water‐soluble homo‐ and copolymers of acrylic acid. Neutral and ionic allyl glycoside monomers, namely allyl‐α‐D‐galactopyranoside and allyl‐β‐D‐glucofuranosidurono‐6,3‐lactone, were synthesized by Fischer glycosidation. These monomers were copolymerized with maleic anhydride and itaconic acid in aqueous and nonaqueous solution. The corresponding copolymers with different structures, degrees of functionalization, and charge densities were characterized by 13C NMR spectroscopy, molecular‐weight measurements, and intrinsic viscosity [η] determination. From these, the monomer reactivity ratios and Mark–Houwink relations were established (see Figure). Copolymerization curves of maleic acid copolymers 6 and 10. M1: mole fraction of allyl monomer 2β and 5α in the feed; m1: mole fraction of allyl monomer in the copolymer. The dashed line shows the course of an ideal alternating copolymerization (excepted: M1 = 0 mol‐%, M1 = 100 mol‐%).magnified imageCopolymerization curves of maleic acid copolymers 6 and 10. M1: mole fraction of allyl monomer 2β and 5α in the feed; m1: mole fraction of allyl monomer in the copolymer. The dashed line shows the course of an ideal alternating copolymerization (excepted: M1 = 0 mol‐%, M1 = 100 mol‐%).

Synthesis of neoglycoproteins containing O-methylated trisaccharides related to excretory/secretory antigens of Toxocara larvae

The disaccharides allyl β- d-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-β- and α- d-galactopyranoside 10a and 10b and the trisaccharides allyl 2- O-methyl-α- l-fucopyranosyl-(1→2)-β- d-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-β- and α- d-galactopyranoside 18a and 18b have been prepared using stepwise assembly of the sugar units. The glycosidic linkages were formed employing the trichloroacetimidate procedure for the attachment of the galactopyranosyl residue and N-iodosuccinimide/triflic acid activation of an ethyl 1-thiofucopyranoside donor for fucosylation. Deprotection furnished the allyl glycosides which were converted into cysteamine-spacered ligands, activated with thiophosgene and subsequently linked to bovine serum albumin. The neoglycoproteins serve as immunoreagents to determine epitope specificities of monoclonal antibodies directed against highly immunogenic O-glycans located at the surface of Toxocara larvae.

SYNTHESIS OF β-d-Glcp-(1→2)-[β-d-Ribf-(1→3)-]α-l-Rhap-(1→3)-α-l-Rhap-(1→2)-α-l-Rhap, THE REPEATING UNIT OF THE LIPOPOLYSACCHARIDE OF Acetobacter diazotrophicus PAL 5

A pentasaccharide, the major repeating unit of the lipopolysaccharide (LPS) of the nitrogen fixing bacterium Acetobacter diazotrophicus PAL 5 was efficiently synthesized as its allyl glycoside using a regio- and stereo-selective strategy. The key acceptor, allyl 3-O-acetyl-4-O-benzoyl-α-l-rhamnopyranoside (3), was prepared by selective 3-O-acetylation of allyl 4-O-benzoyl-α-l-rhamnopyranoside. Condensation of 3 with 2,3,4,6-tetra-O-benzoyl-α-d-glucopyranosyl trichloroacetimidate furnished the disaccharide 5. Deallylation and subsequent trichloroacetimidation of 5 afforded 2,3,4,6-tetra-O-benzoyl-β-d-glucopyranosyl-(1→2)-3-O-acetyl-4-O-benzoyl-α-l-rhamnopyranosyl trichloroacetimidate (10). Selective 3-O-glycosylation of allyl α-l-rhamnopyranoside (1) with 10 followed by benzoylation gave trisaccharide (12), which could be conveniently converted to a donor (14). Condensation of 14 with allyl 3,4-di-O-benzoyl-α-l-rhamnopyranoside (15) gave tetrasaccharide 16. Selective deacetylation of 16 gave the acceptor 17 which was ribosylated to furnish the protected pentasaccharide, and finally deprotection led to the title compound.

HIGHLY DEOXYGENATED SUGARS. I. C2-BRANCHED GLUCOSE DERIVATIVES AND CARBON LINKED DEOXYGENATED DISACCHARIDES 1*

Triacetylglucal (1) is converted with high α-selectivity (>9:1) to the corresponding 2,3-unsaturated allyl and benzyl glycosides 2 and 3 using ferric chloride as the catalyst. The 6-O-silyl-protected allylic alcohol 5 is transformed to the 3,4-unsaturated C2-branched ester 6 or the amide 7 by Claisen rearrangement. The highly deoxygenated iodo lactone 8, resulting from the amide 6 by iodolactonization, is a versatile starting material for chiral building blocks 9–12. The 3,4-unsaturated C2-branched ester 6 is reduced to the aldehyde 14 and converted to a carbon linked disaccharide analogue 16 via cycloaddition with Danishefky's diene. *Dedicated to Professor Dr. Dr. h.c. Frieder Lichtenthaler on the occasion of his 70th birthday.

InBr3-Catalyzed Ferrier Rearrangement: An Efficient Synthesis of C-Pseudoglycals

Glycals react smoothly with silyl nucleophiles such as allyltrimethylsilane, trimethylsilyl cyanide and trimethylsilyl azide in the presence of a catalytic amount of indium tribromide to give the corresponding 2,3-unsaturated allyl glycosides, glycosyl cyanides and glycosyl azides in excellent yields with high α-selectivity.

Synthesis of di- to hexasaccharide 1,2-linked beta-mannopyranan oligomers, a terminal S-linked tetrasaccharide congener and the corresponding BSA glycoconjugates.

Homo oligomers of (1-->2)-beta-D-mannopyranosyl residues have been synthesized in order to study the unique immunological properties of the cell wall mannan of C. albicans. p-Chlorobenzyl-protected ulosyl bromide (2) in combination with the sterically hindered, participating solvent, pivaloyl nitrile, facilitated a new approach for the synthesis of these unique homooligomers ranging from disaccharide up to hexasaccharide. The glycosyl donor 2 demonstrates high diastereoselectivity over both the glycosylation and subsequent reduction step and minimizes the number of protecting group manipulations necessary for the synthesis. Congeners of the (1-->2)-beta-D-mannotetraose were synthesized containing a terminal S-linked (1-->2)-beta-D-mannopyranosyl residue. Deprotection of these compounds afforded the propyl glycosides as well as oligomers with amino terminated aglyconic tethers. The tethers were generated from the oligosaccharide allyl glycosides by photoaddition with 2-aminoethanethiol. The functionalized haptens were coupled to BSA via squarate conjugation, and the degree of incorporation was established by TOF mass spectrometry.

ChemInform Abstract: Sc(OTf)3‐Catalyzed C‐Glycosidation of Glycals: A Facile Synthesis of Allyl Glycosides, Glycosyl Cyanides and Glycosyl Azides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of propyl and 2-aminoethyl glycosides of α- d-galactosyl-(1→3′)-β-lactoside

Propyl and 2-aminoethyl α- d-galactopyranosyl-(1→3′)-β-lactosides ( 1 and 2) were prepared from the corresponding perbenzylated trisaccharide allyl glycoside 6 which, in turn, was obtained by methyl triflate promoted α-galactosylation of benzylated allyl lactoside acceptor 4 with thiogalactoside 3. Transformation of the allyl moiety in compound 6 into 2-azidoethyl one was achieved by cleavage of the double bond followed by reduction into alcohol 9, subsequent mesylation, and mesylate→azide substitution. Alternatively trisaccharide 2 was synthesized using α-galactosylation of selectively benzoylated 2-azidoethyl lactoside 19 with 3 as the key step.

Sc(OTf) 3-catalyzed C-glycosidation of glycals: a facile synthesis of allyl glycosides, glycosyl cyanides and glycosyl azides

The treatment of glycals with allyltrimethylsilane, trimethylsilyl cyanide and trimethylsilyl azide in the presence of catalytic amounts of Sc(OTf) 3 gave the corresponding 2,3-unsaturated allyl glycosides, glycosyl cyanides and glycosyl azides in excellent yields with high α-selectivity.

Synthesis and antibody binding properties of glycodendrimers bearing the tumor related T-antigen

Breast cancer marker T-antigen (Gal(β1-3)αGalNAc) was prepared as an allyl glycoside that was transformed into an active ester and coupled to a series of poly(amidoamine) dendrimers showing strong binding to mouse monoclonal IgG antibodies and serving as useful coating antigens in microtiter plates.

Total Syntheses of Tumor-Related Antigens N3: Probing the Feasibility Limits of the Glycal Assembly Method

The total syntheses of two octasaccharide antigens isolated from human milk, 1 and 2, and their corresponding allyl glycosides, 3 and 4, have been achieved by utilizing the glycal method. Convergent assembly of the core hexasaccharides and concurrent introduction of two alpha-L-fucosyl moieties at the late stage of the syntheses provided these complex carbohydrates in a concise manner. With synthetic material obtained, biological evaluations of these antigens as potential gastrointestinal cancer immunotherapeutic agents have been initiated.

Synthesis of 3- O-sulfoglucuronyl lacto- N-neotetraose 2-aminoethyl glycoside and biotinylated neoglycoconjugates thereof

The 2-aminoethyl glycoside of pentasaccharide 3- O-sulfo-GlcA(β-1→3)Gal(β-1→4)GlcNAc(β-1→3)Gal(β-1→4)Glc(β ( 1) and its conjugates with biotin and biotinylated polyacrylic acid were synthesized as molecular probes to investigate the recognition of the HNK-1 epitope containing carbohydrates by proteins. Key steps in the first of two investigated schemes for the preparation of the target compound 1 were (a) assembling of the pentasaccharide backbone (compound 10) by glycosylation of selectively substituted allyl glycoside of the trisaccharide GlcNAc(β-1→3)Gal(β-1→4)Glc(β with glucuronyl-galactose glycosyl donor, (b) transformation of the allyl aglycon in 10 into 2-azidoethyl one (to give 11), (c) selective deprotection of the OH group at C-3 of the GlcA residue in 11 via saponification, intramolecular formation of 6,3-lacton ( 13) and its methanolysis, and (d) subsequent O-sulfation. The alternative scheme with the use of 2-azido-ethyl glycoside of the trisaccharide GlcNAc(β-1→3)Gal(β-1→4)Glc(β instead of the allyl glycoside 6 was less effective due to smaller yield at the step of pentasaccharide synthesis. Additionally to 1 the 2-aminoethyl glycosides of the oligosaccharides GlcA(β-1→3)Gal(β-1→4)GlcNAc(β-1→3)Gal(β-1→4)Glc(β, 3- O-sulfo-GlcA(β-1→3)Gal(β, and GlcA(β-1→3)Gal(β were also synthesized.

Synthesis of neoglycoproteins containing d- glycero- d- talo-oct-2-ulopyranosylonic acid (Ko) ligands corresponding to core units from Burkholderia and Acinetobacter lipopolysaccharide

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-β- d- talo-oct-2-ulopyranos}onate, prepared from the 4- O- pNBz-protected Ko derivative, was elaborated into the α-Ko allyl ketoside, the reducing disaccharide α-Kdo p-(2→4)-Ko and the disaccharide α-Kdo p-(2→4)-Ko p-(2→OAll). Conversely, methyl[4,5,7,8-tetra- O-acetyl-3- O-(4-nitrobenzoyl)-α- d- glycero- d- talo-2-octulopyranosyl bromide]onate [ Carbohydr. Res., 244 (1993) 69–84], was coupled with a Kdo acceptor to give the disaccharide α-Ko p-(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.

A novel approach to functionalization of allyl aglycon. Effective synthesis of selectively protected 2-aminoethyl lactoside, a common building block for the synthesis of carbohydrate chains of glycolipids

A novel approach to the functionalization of aglycon in allyl glycosides is described. The method comprises ozonolysis of the double bond in the allyl group, leading to the corresponding aldehyde, and subsequent transformation of the latter into the corresponding oxime, which is finally reduced to give the amine. The efficiency of this synthetic sequence (yield ∼90%) is exemplified by the transformation of two allyl lactoside derivatives into selectively protected 2-aminoethyl lactosides. The latter are convenient common building blocks for the synthesis of carbohydrate chains of glycolipids that have a lactose unit at the reducing end.

CARBOHYDRATE MODIFIED POLYDIMETHYLSILOXANES. PART 1. SYNTHESIS AND CHARACTERIZATION OF CARBOHYDRATE SILANE AND SILOXANE BUILDING BLOCKS

A series of silanes containing carbohydrate residues usable as building blocks for the preparation of modified poly(dimethylsiloxane)s(PDMS) were synthesized. Allyl glycosides, allyl ethers and allyl amides of glucose, gluconic acid and glucuronic acid-γ-lactone with protected hydroxyl groups were reacted with diisopropoxymethylsilane in the presence of hydrosilylation catalysts yielding sugar substituted dialkoxysilanes. In addition, di- and trialkoxysilanes containing sugar residues were obtained by reaction of D(+)glucono-δ-lactone with 3-aminopropylsilanes. By hydrosilylation of tetramethylcyclotetrasiloxane with trimethylsilyl (TMS)-protected 3-O-allylglucose a glucose substituted cyclosiloxane was obtained and used in equilibration reactions for the synthesis of water soluble PDMS with pendant sugar moieties.However, the ring double bond of cellobial was found to be unaccessible for hydrosilylations.