Carboxybenzyl Glycoside Research Articles

Stereoselective Synthesis of the Hexasaccharide Repeating Unit of the Cell Wall Polysaccharide from Kineosporia aurantiaca VKM Ac-720T Employing the Direct Glycosylation with Anomeric Hydroxy Sugars Involving Glycosyl Phthalate Intermediates

Synthesis of a suitably protected form of the hexasaccharide repeating unit of the cell wall polymer from Kineosporia aurantiaca VKM Ac-720 T has been achieved by the stereoselective direct glycosylation of a trisaccharide acceptor with a trisaccharide donor having an anomeric hydroxy group involving a glycosyl phthalate intermediate. Both the trisaccharide acceptor and the trisaccharide donor were obtained from a common trisaccharide, of which two β-mannopyranosyl linkages were constructed stereoselectively by employing the direct glycosylation method with the anomeric hydroxy sugar involving a glycosyl phthalate intermediate and the 2′-carboxybenzyl glycoside method, respectively.

ChemInform Abstract: 2′‐Carboxybenzyl Glycosides: A Novel Type of Glycosyl Donors and Their Application to Oligosaccharide Synthesis

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Stereoselective α-galactofuranosylation and synthesis of di- and tetrasaccharide subunits of cell wall polysaccharides of Talaromyces flavus

Stereoselective α-galactofuranosylation employing 2′-carboxybenzyl glycosides as galactosyl donors has been established. The tetrabenzyl-protective group on the galactosyl donor was essential for the α-galactosylation of secondary alcohol acceptors. The present method was successfully applied to the synthesis of di- and tetrasaccharide subunits of cell wall polysaccharides of Talaromyces flavus.

Synthesis of a tetrasaccharide phosphate from the linkage region of the arabinogalactan–peptidoglycan complex in the mycobacterial cell wall

The synthesis of dibenzyl 6- O-naphthylmethyl-2,3,5-tri- O-benzoyl-β- d-galactofuranosyl-(1→5)-2,3-di- O-benzoyl-6- O-benzyl-β- d-galactofuranosyl-(1→4)-3- O-benzyl-2- O-pivaloyl-α- l-rhamnopyranosyl-(1→3)-2-acetamido-2-deoxy-4,6-di- O-benzoyl-α- d-glucopyranosyl phosphate ( 1), a protected form of the tetrasaccharide phosphate of the linkage region of the arabinogalactan–peptidoglycan complex in the mycobacterial cell wall, has been accomplished. Key steps include the coupling of four monosaccharide building blocks with complete stereoselectivity by glycosylations employing thioglycosides, 2′-carboxybenzyl glycosides, and glycosyl fluorides as glycosyl donors. The α-glycosyl phosphate linkage was also stereoselectively elaborated by reaction of a tetrasaccharide hemiacetal with tetrabenzyl pyrophosphate in the presence of a base.

Lactonization‐mediated glycosylations and their application to oligosaccharide synthesis

The concept of lactonization-mediated and related glycosylations led us to develop new methods of glycosylation such as the 2'-carboxybenzyl (CB) glycoside method, the glycosyl pentenoate/phenylselenyl trifluoromethanesulfonate (PhSeOTf) method, and the glycosyl aryl phthalate method. Highly stereoselective beta-mannopyranosylations were achieved by employing the CB glycoside and the glycosyl pentenoate/PhSeOTf methods. The CB glycoside method was also utilized for stereoselective 2-deoxyglycosylation, beta-arabinofuranosylation, and alpha-galactofuranosylation. In addition, these lactonization-mediated methods of glycosylation were employed for the synthesis of complex oligosaccharides. In particular, the CB glycoside method was successfully applied to the synthesis of repeating oligosaccharide subunits of the O-polysaccharide of the lipopolysaccharide from Danish Helicobacter pylori strains and Escherichia coli 077, the synthesis of oligoarabinofuranosides in mycobacterial cell walls, and the total synthesis of antineoplastic agelagalastatin.

Synthesis of Tri-, Hexa-, and Nonasaccharide Subunits of the Atypical O-Antigen Polysaccharide of the Lipopolysaccharide from Danish Helicobacter pylori Strains

Synthesis of trisaccharide repeating unit, -->3)-alpha-D-Rhap-(1-->2)-alpha-D-Manp3CMe-(1-->3)-alpha-L-Rha p-(1-->, and its dimeric hexa- and trimeric nonasaccharide subunits of the atypical O-antigen polysaccharide of the lipopolysaccharide from Danish H. pylori strains D1, D3, and D6 has been accomplished. Successful synthesis of the hexasaccharide and the nonasaccharide was possible by dimerization and trimerization of the suitably protected trisaccharide repeating unit, in which three monosaccharide moieties were arranged in a proper order by placing the sterically demanding 3-C-methyl-D-mannose moiety in between D- and L-rhamnoses. Key steps include the coupling of three monosaccharide moieties and dimerization and trimerization of the trisaccharide unit by glycosylations employing the 2'-carboxybenzyl glycoside method. Also presented is a method for the synthesis of the novel branched sugar, 3-C-methyl-D-mannose moiety by elaboration of its equatorial hydroxyl and axial methyl groups at C-3' in the disaccharide stage.

2′-Carboxybenzyl glycosides: glycosyl donors for C-glycosylation and conversion into other glycosyl donors

Glycosylation of various glycosyl acceptors with 2′-carboxybenzyl (CB) 2,3,4,6-tetra- O-benzyl-β- d-glucopyranoside and CB 2,3,4,6-tetra- O-benzyl-α- d-mannopyranoside as glycosyl donors afforded α-C-glycosides exclusively or predominantly in good yields. CB glycosides were also converted to other well-known glycosyl donors, the corresponding phenyl thioglycoside and the glycosyl fluoride derivatives.

Synthesis of the tetrasaccharide repeat unit of the O-antigen polysaccharide from Escherichia coli O77 employing the 2′-carboxybenzyl glycoside

The synthesis of the suitably protected form (1) of the tetrasaccharide repeat unit, →2)-α-D-Manp-(1→2)-β-D-Manp-(1→3)-α-D-GlcpNAc-(1→6)-α-D-Manp-(1→ (A), of the O-antigen polysaccharide of the lipopolysaccharide from Escherichia coli O77 has been accomplished by latent–active glycosylation employing the 2′-carboxybenzyl (CB) gly coside method. In addition to previously used latent glycosyl donors, 2′-(benzyloxycarbonyl)benzyl (BCB) glycosides, new latent glycosyl donors, 2'-(allyloxycarbonyl)benzyl (ACB) glycosides, have been introduced as a direct precursor for the active CB glycosides. We also demonstrate that 4,6-O-benzylidene-2-azido-2-deoxy-α-D-mannopyranoside (7) has been readily prepared from D-glucosamine in good yield.Key words: Escherichia coli O77, glycosylation, 2′-carboxybenzyl (CB) glycosides, 2′-(allyloxycarbonyl)benzyl (ACB) glycosides, glycosyl donor.

Synthesis of the Trisaccharide Repeating Unit of the Atypical O‐Antigen Polysaccharide from Danish Helicobacter pylori Strains Employing the 2′‐Carboxybenzyl Glycoside.

Synthesis of the unique trisaccharide repeating unit of the O-polysaccharide of the lipopolysaccharide from Danish Helicobacter pylori strains has been accomplished. Key steps include the coupling of three monosaccharide moieties by glycosylations employing the 2‘-carboxybenzyl glycoside method. Also presented is a method for the synthesis of the novel branched sugar, 3-C-methyl-d-mannose, which is one of three monosaccharide components.

Synthesis of the Trisaccharide Repeating Unit of the Atypical O-Antigen Polysaccharide from Danish Helicobacter pylori Strains Employing the 2‘-Carboxybenzyl Glycoside

[reaction: see text] Synthesis of the unique trisaccharide repeating unit of the O-polysaccharide of the lipopolysaccharide from Danish Helicobacter pylori strains has been accomplished. Key steps include the coupling of three monosaccharide moieties by glycosylations employing the 2'-carboxybenzyl glycoside method. Also presented is a method for the synthesis of the novel branched sugar, 3-C-methyl-D-mannose, which is one of three monosaccharide components.

Glycosylation with 2′‐Carboxybenzyl Glycosides as Glycosyl Donors: Scope and Application to the Synthesis of a Tetrasaccharide.

Glycosylation of 2′-carboxybenzyl (CB) 2,3,4,6-tetra-O-benzyl-α-D-mannopyranoside (3), CB 2,3,4,6-tetra-O-benzyl-β-D-glucopyranoside (4), and CB 2,3-di-O-benzyl-4,6-O-benzylidene-β-D-glucopyranoside (5) as glycosyl donorswith various glycosyl acceptors provided corresponding disaccharides in high yields. The present CB glycoside methodology was successfully applied to the efficient construction of the tetrasaccharide 41.

Glycosylation with 2′-Carboxybenzyl Glycosides as Glycosyl Donors: Scope and Application to the Synthesis of a Tetrasaccharide

Glycosylation of 2′-carboxybenzyl (CB) 2,3,4,6-tetra-O-benzyl-α-D-mannopyranoside (3), CB 2,3,4,6-tetra-O-benzyl-β-D-glucopyranoside (4), and CB 2,3-di-O-benzyl-4,6-O-benzylidene-β-D-glucopyranoside (5) as glycosyl donorswith various glycosyl acceptors provided corresponding disaccharides in high yields. The present CB glycoside methodology was successfully applied to the efficient construction of the tetrasaccharide 41.

Solid-phase Synthesis of Oligosaccharides Using Novel Alkyne-type Linkers: Selection of Reactive Sites on the Support by Sonogashira Reaction

Two new alkyne-type linkers having alkynylmethyloxy moieties were elaborated for solid-phase synthesis of oligosaccharides. A propargyl glycoside-type linker between a sugar residue and a solid support was formed by the Sonogashira reaction of a propargyl glycoside with polymer-supported iodobenzene. A propargyl ester-type linker was also constructed by the same reaction of a 4-(proparygyloxycarbonyl)benzyl glycoside with the latter. Both linkers are stable against acids such as TFA but can be readily cleaved with this acid after conversion to the corresponding alkyne-cobalt complex by treatment with Co 2 (CO) 8 . The latter ester linker is generally advantageous in that mild cleavage liberates a product as its carboxybenzyl glycoside which is readily purified. The Sonogashira reaction was found to proceed only at spatially reactive sites on the solid support where the reagent accesses readily, so that the subsequent reactions including glycosylation on solid phase proceeded smoothly to result in high total yields of the desired oligosaccharides.