Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Application of the 4-trifluoromethylbenzenepropargyl ether group as an unhindered, electron deficient protecting group for stereoselective glycosylation.

ABSTRACT: 4-Trifluoromethylbenzenepropargyl ethers are stable and sterically minimal alcohol protecting groups that are readily cleaved in a single step by exposure to lithium naphthalenide. In conjunction with the 4,6-O-benzylidene protecting group, glycosylation reactions of 2-O-(4-trifluoromethylbenzenepropargyl)-protected mannosyl donors are extremely beta-selective.

SUBMITTER: Crich D

PROVIDER: S-EPMC2742709 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Application of the 4-trifluoromethylbenzenepropargyl ether group as an unhindered, electron deficient protecting group for stereoselective glycosylation.

Crich David D Karatholuvhu Maheswaran S MS

The Journal of organic chemistry 20080605 13

4-Trifluoromethylbenzenepropargyl ethers are stable and sterically minimal alcohol protecting groups that are readily cleaved in a single step by exposure to lithium naphthalenide. In conjunction with the 4,6-O-benzylidene protecting group, glycosylation reactions of 2-O-(4-trifluoromethylbenzenepropargyl)-protected mannosyl donors are extremely beta-selective. ...[more]

PMID: 18529028

Similar Datasets

1-naphthylpropargyl ether group: a readily cleaved and sterically minimal protecting system for stereoselective glycosylation.

Project description:[reaction: see text] The (1-naphthyl)propargyl group is introduced as a sterically unobtrusive alcohol protecting group that is cleaved in a single step by exposure to dichlorodicyanoquinone in wet dichloromethane. In conjunction with the 4,6-O-benzylidene protecting group, and the use of the sulfoxide glycosylation method, 3-O-naphthylpropargyl-protected mannosyl donors are extremely beta-selective.

| S-EPMC2615467 | biostudies-literature

Iodine-promoted stereoselective amidosulfenylation of electron-deficient alkynes.

Project description:Iodine-promoted three-component synthesis of substituted β-amino sulfides has been developed starting from a propargyl ester, aliphatic secondary amine, and disulfide. This protocol provides a step-economic and highly regioselective entry to trisubstituted olefins with good substrate scope and functional group tolerance.

| S-EPMC9081554 | biostudies-literature

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group.

Project description:Lipid A, the hydrophobic domain of lipopolysaccharide (LPS), is a strong immunostimulator and therefore a valuable target for the development of novel immunomodulators. Various lipid A derivatives have been chemically synthesized in order to reduce toxicity while retaining the immunostimulatory activity. In this work, we describe a novel approach to the frequently problematic synthesis of monophosphorylated mono- and disaccharide lipid X using a combination of established chemistry and a novel 2-naphthylmethyl ether (Nap) protecting group for "permanent" protection of hydroxy groups. Of particular note is the fact that the key Nap protecting group is able to remain in the molecule until the final global deprotection step. Our synthetic strategy is not only efficient in regards to the yield of the various chemical transformations, but also robust in regards to the potential application of this route to the production of other lipid A analogs.

| S-EPMC7431767 | biostudies-literature

Protecting-group-free <i>S</i>-glycosylation towards thioglycosides and thioglycopeptides in water.

Project description:A facile and green S-glycosylation method has been developed featuring protecting-group-free and proceeding-in-water like enzymatic synthesis. Glycosylation of fluoride donors with thiol sugar acceptors using Ca(OH)2 as a promoter afforded various thioglycosides in good yields with exclusive stereoselectivity. This method also enabled the successful production of S-linked oligosaccharides and S-linked glycopeptides.

| S-EPMC8423405 | biostudies-literature

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center.

Project description:Glycosylation is an immensely important biological process and one that is highly controlled and very efficient in nature. However, in a chemical laboratory the process is much more challenging and usually requires the extensive use of protecting groups to squelch reactivity at undesired reactive moieties. Nonetheless, by taking advantage of the differential reactivity of the anomeric center, a selective activation at this position is possible. As a result, protecting group-free strategies to effect glycosylations are available thanks to the tremendous efforts of many research groups. In this review, we showcase the methods available for the selective activation of the anomeric center on the glycosyl donor and the mechanisms by which the glycosylation reactions take place to illustrate the power these techniques.

| S-EPMC5496566 | biostudies-other

Regioselective single pot C3-glycosylation of strophanthidol using methylboronic acid as a transient protecting group.

Project description:This manuscript describes a single pot protocol for the selective introduction of unprotected sugars to the C3 position of the cardiotonic steroid strophanthidol. These reactions proceed with high levels of regiocontrol (>20:1 rr) in the presence of three other hydroxyl functionalities including the C19 primary hydroxyl group and could be applied to different sugars to provide the deprotected cardiac glycosides upon work up (5 examples, 77-69% yield per single operation). The selective glycosylation of the less reactive C3 position is accomplished by the use of traceless protection with methylboronic acid that blocks the C5 and C19 hydroxyls by forming a cyclic boronic ester, followed by in situ glycosylation and a work up with ammonia in methanol to remove the boronic ester and the carbohydrate ester protecting groups.

| S-EPMC6486442 | biostudies-literature

Stereoselective Cyclopropanation of Electron-Deficient Olefins with a Cofactor Redesigned Carbene Transferase Featuring Radical Reactivity.

Project description:Engineered myoglobins and other hemoproteins have recently emerged as promising catalysts for asymmetric olefin cyclopropanation reactions via carbene transfer chemistry. Despite this progress, the transformation of electron-poor alkenes has proven very challenging using these systems. Here, we describe the design of a myoglobin-based carbene transferase incorporating a non-native iron-porphyrin cofactor and axial ligand, as an efficient catalyst for the asymmetric cyclopropanation of electron-deficient alkenes. Using this metalloenzyme, a broad range of both electron-rich and electron-deficient alkenes are cyclopropanated with high efficiency and high diastereo- and enantioselectivity (up to >99% de and ee). Mechanistic studies revealed that the expanded reaction scope of this carbene transferase is dependent upon the acquisition of metallocarbene radical reactivity as a result of the reconfigured coordination environment around the metal center. The radical-based reactivity of this system diverges from the electrophilic reactivity of myoglobin and most of known organometallic carbene transfer catalysts. This work showcases the value of cofactor redesign toward tuning and expanding the reactivity of metalloproteins in abiological reactions and it provides a biocatalytic solution to the asymmetric cyclopropanation of electrodeficient alkenes. The metallocarbene radical reactivity exhibited by this biocatalyst is anticipated to prove useful in the context of a variety of other synthetic transformations.

| S-EPMC7111255 | biostudies-literature

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 α-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 α-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 α-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

Gold-Catalyzed Hydrofluorination of Electron-Deficient Alkynes: Stereoselective Synthesis of <i>β</i>-Fluoro Michael Acceptors.

Project description:The gold(I)-catalyzed, stereoselective hydrofluorination of electron-deficient alkynes with triethylamine trihydrogen fluoride (Et3N·3HF) is described. Fluorinated α,β-unsaturated aldehydes, amides, esters, ketones, and nitriles were isolated in moderate to good yields as single diastereomers. In all but four cases, the (Z)-vinyl fluorides were initially formed in ≥97% diastereoselectivity. This work constitutes the first catalytic example of the diastereoselective preparation of a variety of β-alkyl, β-fluoro Michael acceptors from alkynes. Additionally, the described work expands access to β-aryl, β-fluoro Michael acceptors to the synthesis of β-fluoro-α,β-unsaturated amides and nitriles. The monofluoroalkenes formed through this strategy were readily transformed into other fluorine-containing compounds, and the developed method was applied to the synthesis of a fluorinated analogue of Exoderil, a topical antimycotic.

| S-EPMC6874379 | biostudies-literature

Electron-deficient pyridinium salts/thiourea cooperative catalyzed O-glycosylation via activation of O-glycosyl trichloroacetimidate donors.

Project description:The glycosylation of O-glycosyl trichloroacetimidate donors using a synergistic catalytic system of electron-deficient pyridinium salts/aryl thiourea derivatives at room temperature is demonstrated. The acidity of the adduct formed by the 1,2-addition of alcohol to the electron-deficient pyridinium salt is increased in the presence of an aryl thiourea derivative as an hydrogen-bonding cocatalyst. This transformation occurs under mild reaction conditions with a wide range of O-glycosyl trichloroacetimidate donors and glycosyl acceptors to afford the corresponding O-glycosides in moderate to good yields with predictable selectivity. In addition, the optimized method is also utilized for the regioselective O-glycosylation by using a partially protected acceptor.

| S-EPMC5687052 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

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