Metal-free and VOC-free O-glycosylation in supercritical CO<sub>2</sub>

Cardona, Adrià; Boutureira, Omar; Castillón, Sergio; Dı́az, Yolanda; Matheu, M. Isabel

doi:10.1039/c7gc00722a

Cited by 19 publications

(10 citation statements)

References 70 publications

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“…The influence of pressure, temperature, protecting and leaving groups on these reactions, which were conducted in the absence of external promotor, were noted but a satisfactory explanation awaits further work. 285…”

Section: Influence Of Solventmentioning

confidence: 99%

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

et al. 2018

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A critical review of the state-of-the-art evidence in support of the mechanisms of glycosylation reactions is provided. Factors affecting the stability of putative oxocarbenium ions as intermediates at the S1 end of the mechanistic continuum are first surveyed before the evidence, spectroscopic and indirect, for the existence of such species on the time scale of glycosylation reactions is presented. Current models for diastereoselectivity in nucleophilic attack on oxocarbenium ions are then described. Evidence in support of the intermediacy of activated covalent glycosyl donors is reviewed, before the influences of the structure of the nucleophile, of the solvent, of temperature, and of donor-acceptor hydrogen bonding on the mechanism of glycosylation reactions are surveyed. Studies on the kinetics of glycosylation reactions and the use of kinetic isotope effects for the determination of transition-state structure are presented, before computational models are finally surveyed. The review concludes with a critical appraisal of the state of the art.

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Section: Influence Of Solventmentioning

confidence: 99%

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

et al. 2018

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“…In glycosylation reactions the solvent plays a critical role in terms of stabilizing the oxocarbenium ion intermediate and/or affecting the α,β-selectivity [1]. In 2017, Matheu et al reported a ″green″ glycosylation procedure by employing supercritical CO 2 (scCO 2 ) as a weakly Lewis acidic reaction medium [37]. The method was successfully applied for the synthesis of O-glycosides from disarmed glycosyl chlorides and bromides in the absence of additional promoter.…”

Section: Introductionmentioning

confidence: 99%

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

Gulbe¹,

Lugiņina²,

Jansons³

et al. 2021

Beilstein J. Org. Chem.

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Liquid SO2 is a polar solvent that dissolves both covalent and ionic compounds. Sulfur dioxide possesses also Lewis acid properties, including the ability to covalently bind Lewis basic fluoride ions in a relatively stable fluorosulfite anion (FSO2 −). Herein we report the application of liquid SO2 as a promoting solvent for glycosylation with glycosyl fluorides without any external additive. By using various temperature regimes, the method is applied for both armed and disarmed glucose and mannose-derived glycosyl fluorides in moderate to excellent yields. A series of pivaloyl-protected O- and S-mannosides, as well as one example of a C-mannoside, are synthesized to demonstrate the scope of the glycosyl acceptors. The formation of the fluorosulfite species during the glycosylation with glycosyl fluorides in liquid SO2 is proved by 19F NMR spectroscopy. A sulfur dioxide-assisted glycosylation mechanism that proceeds via solvent separated ion pairs is proposed, whereas the observed α,β-selectivity is substrate-controlled and depends on the thermodynamic equilibrium.

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“…More recently, other types of promoters that do not rely on the use of metal salts have been introduced. Selected examples include halogen or halonium ion with or without additives, organocatalysts, diarylborinic acid, glycosylation modulators such as pyridine, DMF, 3,3‐difluoroxindole (HOFox), phenanthroline, and super critical CO 2 . However, many of these reactions still suffer from low rates and some have a limited substrate scope.…”

Section: Introductionmentioning

confidence: 99%

Defining the Scope of the Acid‐Catalyzed Glycosidation of Glycosyl Bromides

Singh

Demchenko

2019

Chemistry A European J

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Who designed the cover?We have been collaborating with Fabia D'Amore-Krug, at alented artist who teaches art therapy.F or our previous covers, all we had to do is describe the general outcome of our article in lay terms, and she would immediately come up with an image in her head. The fact that this reaction can now proceed much faster was shown by Fabia with two cars:o ld and slow versus new and fast. She quickly sketched the image of the two cars racing each other and came up with other ideas, such as gas stations, St. Louis skyline, etc. Fabia's initial sketch was done in pencil and then she created her final image in beautiful watercolor.

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Metal-free and VOC-free O-glycosylation in supercritical CO₂

Cited by 19 publications

References 70 publications

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

Defining the Scope of the Acid‐Catalyzed Glycosidation of Glycosyl Bromides

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Metal-free and VOC-free O-glycosylation in supercritical CO2

Cited by 19 publications

References 70 publications

The Experimental Evidence in Support of Glycosylation Mechanisms at the SN1–SN2 Interface

The Experimental Evidence in Support of Glycosylation Mechanisms at the SN1–SN2 Interface

Metal-free glycosylation with glycosyl fluorides in liquid SO2

Defining the Scope of the Acid‐Catalyzed Glycosidation of Glycosyl Bromides

Contact Info

Product

Resources

About

Metal-free and VOC-free O-glycosylation in supercritical CO₂

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

The Experimental Evidence in Support of Glycosylation Mechanisms at the S_N1–S_N2 Interface

Metal-free glycosylation with glycosyl fluorides in liquid SO₂