Browse
Submit Data
Databases
API
Help

Dataset Information

13 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Stereoselective Synthesis of the Equatorial Glycosides of Legionaminic Acid.

ABSTRACT: The synthesis of a legionaminic acid donor from N-acetylneuraminic acid in 15 steps and 17% overall yield is described. Activation of the adamantanyl thioglycoside in the donor with N-iodosuccinimide and trifluoromethanesulfonic acid in dichloromethane and acetonitrile at -78 °C in the presence of primary, secondary and tertiary alcohols affords the corresponding glycosides in excellent yield and good to excellent equatorial selectivity. In particular, coupling to the 4-OH of a suitably protected neuraminic acid derivative affords a disaccharide that closely resembles the glycosidic linkage in the polylegionaminic acid from the lipopolysaccharide of the Legionella pneumophila virulence factor. A straightforward deprotection sequence enables conversion of the protected glycosides to the free N,N-diacetyllegionaminic acid glycosides.

SUBMITTER: Popik O

PROVIDER: S-EPMC5545936 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Stereoselective Synthesis of the Equatorial Glycosides of Legionaminic Acid.

Popik Oskar O Dhakal Bibek B Crich David D

The Journal of organic chemistry 20170602 12

The synthesis of a legionaminic acid donor from N-acetylneuraminic acid in 15 steps and 17% overall yield is described. Activation of the adamantanyl thioglycoside in the donor with N-iodosuccinimide and trifluoromethanesulfonic acid in dichloromethane and acetonitrile at -78 °C in the presence of primary, secondary and tertiary alcohols affords the corresponding glycosides in excellent yield and good to excellent equatorial selectivity. In particular, coupling to the 4-OH of a suitably protecte ...[more]

PMID: 28530837

Similar Datasets

The isothiocyanato moiety: an ideal protecting group for the stereoselective synthesis of sialic acid glycosides and subsequent diversification.

Project description:The preparation of a crystalline, peracetyl adamantanyl thiosialoside donor protected by an isothiocyanate group is described. On activation at -78?°C in the presence of typical carbohydrate acceptors, this donor gives high yields of the corresponding sialosides with exquisite ?-selectivity. The high selectivity extends to the 4-O-benzyl-protected 3-OH acceptors, which are typically less reactive and selective than galactose 3,4-diols. Treatment of the ?-sialosides with tris(trimethylsilyl)silane or allyltris(trimethylsilyl)silane results in replacement of the C5-N5 bond by a C-H or a C-C bond. The reaction of the isothiocyanate-protected sialosides with thioacids generates amides, while reaction with an amine gives a thiourea, which can be converted into a guanidine. The very high ?-selectivities observed with the new donor and the rich chemistry of the isothiocyante function considerably extend the scope for optimization at the sialoside 5-position.

| S-EPMC4300277 | biostudies-literature

Stereocontrolled Synthesis of the Equatorial Glycosides of 3-Deoxy-d-manno-oct-2-ulosonic Acid: Role of Side Chain Conformation.

Project description:The pseudosymmetric relationship of the bacterial sialic acid, pseudaminic acid, and 3-deoxy-d-manno-oct-2-ulosonic acid (KDO) affords the hypothesis that suitably protected KDO donors will adopt the trans, gauche conformation of their side chain and consequently be highly equatorially selective in their coupling reactions conducted at low temperature. This hypothesis is borne out by the synthesis, conformational analysis, and excellent equatorial selectivity seen on coupling of per-O-acetyl or benzyl-protected KDO donors in dichloromethane at -78 °C. Mechanistic understanding of glycosylation reactions is advancing to a stage at which predictions of selectivity can be made. In this instance, predictions of selectivity provide the first highly selective entry into KDO equatorial glycosides such as are found in the capsular polysaccharides of numerous pathogenic bacteria.

| S-EPMC7213052 | biostudies-literature

Stereoselective synthesis of 2-deoxy-beta-glycosides using anomeric O-alkylation/arylation.

Project description:Anomeric O-alkylation/arylation is applied to the synthesis of 2-deoxy-beta-glycosides. Treatment of lactols with NaH in dioxane followed by the addition of electrophiles leads to the formation of 2-deoxy-beta-glycosides in high yield and high selectivity. The high beta-selectivity observed here demonstrates a powerful stereoelectronic effect for the stereoselective formation of acetals under kinetic control.

| S-EPMC2699938 | biostudies-literature

Robust perfluorophenylboronic acid-catalyzed stereoselective synthesis of 2,3-unsaturated O-, C-, N- and S-linked glycosides.

Project description:A convenient protocol was developed for the synthesis of 2,3-unsaturated C-, O-, N- and S-linked glycosides (enosides) using 20 mol % perflurophenylboronic acid catalyst via Ferrier rearrangement. Using this protocol, D-glucals and L-rhamnals reacted with various C-, O-, N- and S-nucleophiles to give a wide range of glycosides in up to 98% yields with mainly α-anomeric selectivity. The perflurophenylboronic acid successfully catalyzed a wide range of substrates (both glucals and nucleophiles) under very mild reaction conditions.

| S-EPMC6604698 | biostudies-literature

Highly stereoselective Bronsted acid catalyzed synthesis of spirooxindole pyrans.

Project description:A Brønsted acid-catalyzed Prins-type cyclization sequence to construct spirooxindole pyrans in high yields and excellent diastereoselectivity has been developed. The combination of a ?-hydroxy dioxinone fragment and isatin dimethyl acetal generate oxa-spirooxindoles efficiently. These compounds are diversifiable scaffolds that tap into the rich chemistry of dioxinones.

| S-EPMC3115630 | biostudies-literature

Stereoselective semi-synthesis of the neuroprotective natural product, serofendic acid.

Project description:We have recently demonstrated a synthetic biology-enabled semi-synthesis of the potent neuroprotective compound, serofendic acid. An engineered bacterium produces ent-atis-16-en-19-oic acid, which has six of eight chiral carbons configured with the appropriate stereochemistry. Setting the configuration of the C15 hydroxyl group and C16 methylene is a critical step that occurs late in each published total or formal synthesis. Here we explore the use of alternative reducing reagents, stereochemical directing agents, reaction order, and product recycling to improve the diastereoselectivity of this step. We find that installing and oxidizing the C17 methylsulfide prior to reducing the C15 ketone provides the greatest yield of the desired C15,C16 diastereomer. This represents an improved total synthesis of serofendic acid.

| S-EPMC6595966 | biostudies-literature

An Improved Helferich Method for the α/β-Stereoselective Synthesis of 4-Methylumbelliferyl Glycosides for the Detection of Microorganisms.

Project description:An improved Helferich method is presented. It involves the glycosylation of 4-methyl-umbelliferone with glycosyl acetates in the presence of boron trifluoride etherate combined with triethylamine, pyridine, or 4-dimethylaminopyridine under mild conditions, followed by deprotection to give fluorogenic 4-methylumbelliferyl glycoside substrates. Due to the use of base, the glycosylation reaction proceeds more easily, is uncommonly α- or β-stereoselective, and affords the corresponding products in moderate to excellent yields (51%-94%) under appropriate conditions.

| S-EPMC6331929 | biostudies-literature

Silver-catalyzed stereoselective formation of glycosides using glycosyl ynenoates as donors.

Project description:A silver-catalyzed glycosylation reaction employing readily accessible and stable glycosyl ynenoates is developed. This reaction is mostly high yielding and exhibits varying levels of stereoinversion at the anomeric position. Compared to established and versatile Yu's gold catalysis, this chemistry features the use of substantially cheaper AgNTf2.

| S-EPMC6080613 | biostudies-literature

Cooperative Bronsted Acid-Type Organocatalysis for the Stereoselective Synthesis of Deoxyglycosides.

Project description:A practical approach for the ?-stereoselective synthesis of deoxyglycosides using cooperative Brønsted acid-type organocatalysis has been developed. The method is tolerant of a wide range of glycoside donors and acceptors, and its versatility is exemplified in the one-pot synthesis of a trisaccharide. Mechanistic studies suggest that thiourea-induced acid amplification of the chiral acid via H-bonding is key for the enhancement in reaction rate and yield, while stereocontrol is dependent on the chirality of the acid.

| S-EPMC5309864 | biostudies-literature

Stereoselective iterative one-pot synthesis of N-glycolylneuraminic acid-containing oligosaccharides.

Project description:The use of an N-acyloxazolidinone-protected S-adamantanyl thiosialoside allows the highly stereoselective, one-pot multicomponent synthesis of alpha-sialoside-based oligosaccharides.

| S-EPMC2726932 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data