An Efficient Synthesis of <i>N</i>-Allylglycosylamides from Unprotected Carbohydrates

Spevak, Wayne; Dasgupta, Falguni; Hobbs, Christopher; Nagy, Jon O.

doi:10.1021/jo9522522

Cited by 24 publications

(16 citation statements)

References 33 publications

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“…Sialyllactose Neoglycolipid-The sialyllactose neoglycolipid was synthesized from 1-␤-O-allyllactose by first forming an N-allyl glycoside (42) and then coupling the glycosylamine to steroyl chloride. A solution of 0.63 g (1.0 mmol) of sialyllactose (NeuAc␣233Gal␤134Glc) (Neose, Horsham, PA) in 10 ml of allylamine was stirred at room temperature for 72 h. The solvent was removed by rotary evaporation, and the resulting residue was suspended in hexanes and evaporated five times.…”

Section: Methodsmentioning

confidence: 99%

Minimal Sulfated Carbohydrates for Recognition by L-selectin and the MECA-79 Antibody

Bruehl¹,

Bertozzi²,

Rosen³

2000

Journal of Biological Chemistry

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Sulfated forms of sialyl-LeX containing Gal-6-SO 4 or GlcNAc-6-SO 4 have been implicated as potential recognition determinants on high endothelial venule ligands for L-selectin. The optimal configuration of sulfate esters on the N-acetyllactosamine (Gal␤134GlcNAc) core of sulfosialyl-Le X , however, remains unsettled. Using a panel of sulfated lactose (Gal␤134Glc) neoglycolipids as substrates in direct binding assays, we found that 6,6-disulfolactose was the preferred structure for L-selectin, although significant binding to 6-and 6-sulfolactose was observed as well. Binding was EDTA-sensitive and blocked by L-selectin-specific monoclonal antibodies. Surprisingly, 6,6-disulfolactose was poorly recognized by MECA-79, a carbohydrate-and sulfate-dependent monoclonal antibody that binds competitively to L-selectin ligands. Instead, MECA-79 bound preferentially to 6-sulfolactose. The difference in preferred substrates between L-selectin and MECA-79 may explain the variable activity of MECA-79 as an inhibitor of lymphocyte adhesion to high endothelial venules in lymphoid organs. Our results suggest that both Gal-6-SO 4 and GlcNAc-6-SO 4 may contribute to L-selectin recognition, either as components of sulfosialyl-Le X capping groups or in internal structures. By contrast, only GlcNAc-6-SO 4 appears to contribute to MECA-79 binding. L-selectin, the "leukocyte selectin," mediates the tethering and rolling of lymphocytes along high endothelial venules (HEVs) 1 in peripheral lymph nodes, a prerequisite for extravasation of the lymphocytes (1-3). By virtue of a calcium-type lectin domain at its amino terminus, L-selectin functions as a calcium-dependent, carbohydrate-binding receptor that recognizes a set of discrete counter-receptors (generally termed ligands) displayed on the luminal aspect of HEVs (reviewed in Refs. 4 and 5). Several HEV-expressed, L-selectin-reactive ligands (all of which possess mucin-like domains) have been identified as potential physiological ligands for L-selectin (reviewed in Ref. 6). These include GlyCAM-1 (7), CD34 (8, 9), and podocalyxin (10).A large body of evidence has established that the optimal interaction between L-selectin and these HEV-expressed ligands requires sialylation, fucosylation, and carbohydrate sulfation (11)(12)(13)(14)(15)(16)(17). In an attempt to rationalize these requirements in terms of carbohydrate structures, a detailed analysis of the O-linked oligosaccharide side chains of GlyCAM-1 was conducted (18 -20). Sulfation analysis of acid-hydrolyzed glycans revealed monosulfated monosaccharides and disaccharides (Nacetyllactosamine) with equivalent levels of Gal-6-SO 4 and GlcNAc-6-SO 4 . Analysis of the simplest oligosaccharide side chains identified equivalent levels of two novel sulfated isomers of sialyl-Le X (sLe X ), 6Ј-sulfo-sLe X , containing Gal-6-SO 4 , and 6-sulfo-sLe X , containing GlcNAc-6-SO 4 (see Fig. 1), as capping groups of core-2 branched oligosaccharides. The finding of a sLe X motif was significant because this tetrasaccharide binds to all three sel...

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Section: Methodsmentioning

confidence: 99%

Minimal Sulfated Carbohydrates for Recognition by L-selectin and the MECA-79 Antibody

Bruehl¹,

Bertozzi²,

Rosen³

2000

Journal of Biological Chemistry

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“…[2] Of the adducts characterized by X-ray crystallography to date [3±5] the (m-h 2 :h 2 -peroxo)-and bis(m-oxo)dicopper units A and B, respectively, have drawn particular attention as a consequence of their known or potential relevance to intermediates in hydroxylation reactions performed by copper oxygenases such as tyrosinase and particularly methane monooxygenase (pMMO). [6] Although B has yet to be observed in an enzyme system, the possibility that A (identified as an intermediate in tyrosinase and catechol oxidase) may convert into B prior to activation of the substrate CÀH bond is supported by the observed reactivity of synthetic examples of these cores. [5,7,8] Evidence in support of the ability of core B to hydroxylate arene rings, [9] to abstract H atoms from the weak CÀH bonds of dihydroanthracene, [10] and to oxidatively N-dealkylate ligand substituents has been uncovered.…”

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confidence: 99%

Aliphatic Hydroxylation by a Bis(μ-oxo)dicopper(III) Complex

Itoh

Taki

Nakao

et al. 2000

Angewandte Chemie International Edition

151

114

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By using molecular oxygen bis(µ-oxo)dicopper(III) complexes can be produced from Cu(I) complexes with ligand L(X) (L(X)=p-substituted N-ethyl-N-[2-(2-pyridyl)ethyl]-2-phenylethylamine; X=OMe, Me, H, Cl, NO(2)) in which the benzylic position of the ligand is activated and hydroxylated by the Cu(2)O(2) core (see reaction scheme). Detailed characterization of this new C-H bond activation reaction by the bis(µ-oxo)dicopper(III) core reveals important information on the fundamental chemistry underlying copper monooxygenase reactivity.

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“…A general solution for this synthetic problem does not exist as yet. This holds true especially for the common metal-organic reactions as they are Reformatsky reaction [2,3], Knoevenagel reaction [4][5][6][7], allylation [8][9][10][11] or aldol reaction [12].…”

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confidence: 99%

Organocatalyzed Cascade Reaction in Carbohydrate Chemistry

Mahrwald

2015

SpringerBriefs in Molecular Science

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The extensive and extremely strong development of organocatalysis over the last years provided versatile methodologies for convenient utilization of the carbonyl function of unprotected carbohydrates in C-C-bond formation processes. These biomimetic amine-activated mechanisms enable multiple cascade-protocols for the synthesis of a large scope of carbohydrate derived compound classes. Several, only slightly different protocols have been developed for the application of 1.3-dicarbonyls in stereoselective chain-elongation of unprotected carbohydrates and the synthesis of highly functionalized C-glycosides of defined configuration. Furthermore, the latter class of compounds can also be accessed by the use of methyl ketones. So a high substrate scope is available for the installation of desired functionalities in C-glycosides. By a one-pot, operationally simple cascade reaction of isocyanides with unprotected aldoses and amino acids an access to a broad range of defined glycosylated pseudopeptides is given. The elaborated organocatalyzed cascade-reactions provide defined access to highly functionalized carbohydrate derivatives. Depending on the reaction conditions different origin to control the installation of configuration during the bond-formation process were observed. The demonstrated organocatalyzed cascade sequences indicate the great potential of unprotected carbohydrates in the synthesis of highly functionalized bio-mimetic structure motifs by operationally simple, one-pot protocols.Due to the great biological importance of carbon chain elongated carbohydrates, the synthesis of this structural diverse compound class has attracted high synthetic interest from the scientific community. Among the elongated carbohydrates, C-Glycosides have gained considerable importance over the last few decades, since they are configuratively stable under enzymatic conditions and less prone to cleavage at the anomeric carbon. As such they are appealing substrates for chemical biology and medicinal chemistry.

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An Efficient Synthesis of N-Allylglycosylamides from Unprotected Carbohydrates

Cited by 24 publications

References 33 publications

Minimal Sulfated Carbohydrates for Recognition by L-selectin and the MECA-79 Antibody

Minimal Sulfated Carbohydrates for Recognition by L-selectin and the MECA-79 Antibody

Aliphatic Hydroxylation by a Bis(μ-oxo)dicopper(III) Complex

Organocatalyzed Cascade Reaction in Carbohydrate Chemistry

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