The Evaluation of Glyceryl C3-Azolyl-Thiogalactosides as Galectin-1 and Galectin-3 Ligands.

Galectins are a family of galactoside-binding proteins involved in various pathophysiological processes, which makes them attractive targets for drug discovery. The derivatization of d-galactose at C3 and C1 positions has been shown to increase the affinity of synthetic galectin antagonists. In this study, two small libraries of d-galactose derivatives have been designed and synthesized.

The synthesis and characterization of electron-poor glycosylamines and derived glycosylamides.

This paper describes a unified approach toward diglycosylamines using methanolic ammonia. All the glycosylamines prepared have been fully characterized, and their anomeric configuration has been determined. The article presents a novel method for the N-acylation of diglycosylamines and other electron-poor glycosylamines, which employs nitromethane as a solvent in carboxylic anhydride acylation under acidic conditions.

On the origin of the electronic and magnetic circular dichroism of naphthyl C-glycosides: Anomeric configuration.

Aryl C-glycosides, in which the glycosidic bond is changed to a carbon-carbon bond, are an important family of biologically-active compounds. They often serve as secondary metabolites or exhibit antibiotic and cytostatic activities. Their stability to hydrolysis has made them attractive targets for new drugs.

Selection of Galectin-Binding Ligands from Synthetic Glycopeptide Libraries.

Galectins, a class of carbohydrate-binding proteins, play a crucial role in various physiological and disease processes. Therefore, the identification of ligands that efficiently bind these proteins could potentially lead to the development of new therapeutic compounds. In this study, we present a method that involves screening synthetic click glycopeptide libraries to identify lectin-binding ligands with low micromolar affinity.

Silicon-bridged (1→1)-disaccharides: an umpoled glycomimetic scaffold.

Modification of the carbohydrate scaffold is an important theme in drug and vaccine discovery. Therefore, the preparation of novel types of glycomimetics is of interest in synthetic carbohydrate chemistry. In this manuscript, we present an early investigation of the synthesis, structure, and conformational behaviour of (1→1)--disaccharides as a novel type of glycomimetics arising from the replacement of interglycosidic oxygen with a dimethyl-, methylpropyl-, or diisopropylsilyl linkage.

Unlocking the Hydrolytic Mechanism of GH92 α-1,2-Mannosidases: Computation Inspires the use of C-Glycosides as Michaelis Complex Mimics.

The conformational changes in a sugar moiety along the hydrolytic pathway are key to understand the mechanism of glycoside hydrolases (GHs) and to design new inhibitors. The two predominant itineraries for mannosidases go via S →B → S and S → H → C . For the CAZy family 92, the conformational itinerary was unknown.

Facile Approach to C-Glucosides by Using a Protecting-Group-Free Hiyama Cross-Coupling Reaction: High-Yielding Dapagliflozin Synthesis.

Invited for the cover of this issue is Kamil Parkan and co-workers at University of Chemistry and Technology and Institute of Organic Chemistry and Biochemistry, Prague. The cover graphic depicts a schematic representation of the assembly of aryl-C-glycosides based on a protecting-group-free Hiyama reaction. Read the full text of the article at 10.

Facile Approach to C-Glucosides by Using a Protecting-Group-Free Hiyama Cross-Coupling Reaction: High-Yielding Dapagliflozin Synthesis.

Access to unprotected (hetero)aryl pseudo-C-glucosides via a mild Pd-catalysed Hiyama cross-coupling reaction of protecting-group-free 1-diisopropylsilyl-d-glucal with various (hetero)aryl halides has been developed. In addition, selected unprotected pseudo-C-glucosides were stereoselectively converted into the corresponding α- and β-C-glucosides, as well as 2-deoxy-β-C-glucosides. This methodology was applied to the efficient and high-yielding synthesis of dapagliflozin, a medicament used to treat type 2 diabetes mellitus.

Straightforward synthesis of protected 2-hydroxyglycals by chlorination-dehydrochlorination of carbohydrate hemiacetals.

A straightforward and scalable method for the synthesis of protected 2-hydroxyglycals is described. The approach is based on the chlorination of carbohydrate-derived hemiacetals, followed by an elimination reaction to establish the glycal moiety. 1,2-dehydrochlorination reactions were studied on a range of glycosyl chlorides to provide suitable reaction conditions for this transformation.

Lectin PLL3, a Novel Monomeric Member of the Seven-Bladed β-Propeller Lectin Family.

The species is a Gram-negative bacteria of the family that is known for its mutualistic relationship with nematodes and pathogenicity toward insects. This study is focused on the characterization of the recombinant lectin PLL3 with an origin in subsp. .

MOP and EE Protecting Groups in Synthesis of α- or β-Naphthyl--Glycosides from Glycals.

The development of effective protection strategies is essential in the synthesis of complex carbohydrates and glycomimetics. This article describes a versatile four-stage protocol for the synthesis of α- or β-aryl--glycosides from unprotected d-glycals using two acetal protecting groups, ethoxyethyl and methoxypropyl, which are stable under harsh basic conditions and convenient for the C-1 metalation of glycals. Their stability was investigated in subsequent cross-coupling reactions with 1-iodonaphthalene followed by oxidative/reductive transformations to naphthyl--glycosides.

Limitations in the description of conformational preferences of C-disaccharides: The (1 → 3)-C-mannobiose case.

Conformational preferences of two C-glycosyl analogues of Manp-(1 → 3)-Manp, were studied using a combined method of theoretical and experimental chemistry. Molecular dynamics was utilized to provide conformational behavior along C-glycosidic bonds of methyl 3-deoxy-3-C-[(α-d-mannopyranosyl)methyl]-α-d- and l-mannopyranosides. The OPLS2005 and Glycam06 force fields were used.

Polyvalent C-glycomimetics based on l-fucose or d-mannose as potent DC-SIGN antagonists.

The C-type lectin DC-SIGN expressed on immature dendritic cells is a promising target for antiviral drug development. Previously, we have demonstrated that mono- and divalent C-glycosides based on d-manno and l-fuco configurations are promising DC-SIGN ligands. Here, we described the convergent synthesis of C-glycoside dendrimers decorated with 4, 6, 9, and 12 α-l-fucopyranosyl units and with 9 and 12 α-d-mannopyranosyl units.

Nonhydrolyzable C-disaccharides, a new class of DC-SIGN ligands.

The discovery of effective ligands for DC-SIGN receptor is one of the most challenging concepts of antiviral drug design due to the importance of this C-type lectin in infection processes. DC-SIGN recognizes mannosylated and fucosylated oligosaccharides but glycosidic linkages are accessible to both chemical and enzymatic degradations. To avoid this problem, the synthesis of stable glycoside mimetics has attracted increasing attention.

Synthesis and evaluation of 2-pyridinylpyrimidines as inhibitors of HIV-1 structural protein assembly.

In an effort to identify an HIV-1 capsid assembly inhibitor with improved solubility and potency, we synthesized two series of pyrimidine analogues based on our earlier lead compound N-(4-(ethoxycarbonyl)phenyl)-2-(pyridine-4-yl)quinazoline-4-amine. In vitro binding experiments showed that our series of 2-pyridine-4-ylpyrimidines had IC50 values higher than 28μM. Our series of 2-pyridine-3-ylpyrimidines exhibited IC50 values ranging from 3 to 60μM.

Specific Inhibitors of HIV Capsid Assembly Binding to the C-Terminal Domain of the Capsid Protein: Evaluation of 2-Arylquinazolines as Potential Antiviral Compounds.

Assembly of human immunodeficiency virus (HIV-1) represents an attractive target for antiretroviral therapy which is not exploited by currently available drugs. We established high-throughput screening for assembly inhibitors based on competition of small molecules for the binding of a known dodecapeptide assembly inhibitor to the C-terminal domain of HIV-1 CA (capsid). Screening of >70000 compounds from different libraries identified 2-arylquinazolines as low micromolecular inhibitors of HIV-1 capsid assembly.

Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes.

Cross-metathesis of α- and β-vinyl C-deoxyribosides and α-vinyl C-galactoside with various terminal alkenes under different conditions was studied. The cross-metathesis of the former proceeded with good yields of the corresponding products in ClCH2CH2Cl the latter required the presence of CuI in CH2Cl2 to achieve good yields of the products. A simple method for the preparation of α- and β-vinyl C-deoxyribosides was also developed.

Modular Stereoselective Synthesis of (1→2)-C-Glycosides based on the sp(2) -sp(3) Suzuki-Miyaura Reaction.

This work reports a modular and rapid approach to the stereoselective synthesis of a variety of α- and β-(1→2)-linked C-disaccharides. The key step is a Ni-catalyzed cross-coupling reaction of D-glucal pinacol boronate with alkyl halide glycoside easily prepared from commercially available D-glucal. The products of this sp(2) -sp(3) cross-coupling reaction can be converted to glucopyranosyl, mannopyranosyl, or 2-deoxy-glucopyranosyl C-mannopyranosides by one- or two-step stereoselective oxidative-reductive transformations.

Cross-coupling reaction of saccharide-based alkenyl boronic acids with aryl halides: the synthesis of bergenin.

A convenient synthetic pathway enabling D-glucal and D-galactal pinacol boronates to be prepared in good isolated yields was achieved. Both pinacol boronates were tested in a series of cross-coupling reactions under Suzuki-Miyaura cross-coupling conditions to obtain the corresponding aryl, heteroaryl, and alkenyl derivatives in high isolated yields. This methodology was applied to the formal synthesis of the glucopyranoside moiety of papulacandin D and the first total synthesis of bergenin.

Covalent stabilization: a sturdy molecular square from reversible metal-ion-directed self-assembly.

Supramolecular self-assembly using weak interactions under quasi-equilibrium conditions has provided easy access to very complex but often quite fragile molecules. We now show how a labile structure obtained from reversible transition-metal-directed self-assembly of rods and connectors serves as a template that can be converted into a sturdy structure of identical topology and similar geometry. The process consists of Cu(I)-catalyzed replacement of all rods or connectors terminated with pyridines for analogues terminated with ethynyls, converting dative N→Pt(+) bonds into covalent C-Pt bonds.

An approach to stereoselective preparation of 3-C-glycosylated D- and L-glucals.

An approach to stereoselective synthesis of alpha- or beta-3-C-glycosylated L- or D-1,2-glucals starting from the corresponding alpha- or beta-glycopyranosylethanals is described. The key step of the approach is the stereoselective cycloaddition of chiral vinyl ethers derived from both enantiomers of mandelic acid. The preparation of 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4,6-tetra-O-benzyl-beta-D-glucopyranosyl)methyl]-L-arabino-hex-1-enitol, 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4,6-tetra-O-benzyl-beta-D-glucopyranosyl)methyl]-D-arabino-hex-1-enitol, and 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4-tri-O-benzyl-alpha-L-fucopyranosyl)methyl]-D-arabino-hex-1-enitol serves as an example of this approach.