Browse
Submit Data
Databases
API
Help

Dataset Information

11 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Metal-free glycosylation with glycosyl fluorides in liquid SO₂.

ABSTRACT: 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.

SUBMITTER: Gulbe K

PROVIDER: S-EPMC8093551 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Aqueous Glycosylation of Unprotected Sucrose Employing Glycosyl Fluorides in the Presence of Calcium Ion and Trimethylamine.

Project description:We report a synthetic glycosylation reaction between sucrosyl acceptors and glycosyl fluoride donors to yield the derived trisaccharides. This reaction proceeds at room temperature in an aqueous solvent mixture. Calcium salts and a tertiary amine base promote the reaction with high site-selectivity for either the 3'-position or 1'-position of the fructofuranoside unit. Because nonenzymatic aqueous oligosaccharide syntheses are underdeveloped, mechanistic studies were carried out in order to identify the origin of the selectivity, which we hypothesized was related to the structure of the hydroxyl group array in sucrose. The solution conformation of various monodeoxysucrose analogs revealed the co-operative nature of the hydroxyl groups in mediating both this aqueous glycosyl bond-forming reaction and the site-selectivity at the same time.

| S-EPMC4817112 | biostudies-literature

The hydrolysis of glycosyl fluorides by glycosidases.

Project description:1. alpha-d- and beta-d-Glucopyranosyl, alpha-d- and beta-d-galactopyranosyl, alpha-d-mannopyranosyl and alpha-d-xylopyranosyl fluorides were hydrolysed specifically by the respective glycosidases from several sources. 2. Use of specific inhibitors with a mixture of glycosidases from Helix pomatia intestinal juice showed that each glycosyl fluoride was hydrolysed only by the respective glycosidase. alpha-d-Glucopyranosidase and alpha-d-xylopyranosidase activities were shown to be due to different enzymes. 3. Partially purified enzyme preparations containing only one of the glycosidase activities hydrolysed only the corresponding glycosyl fluoride. 4. The configuration at C-1 of alpha-d-mannopyranosyl fluoride was confirmed since it was hydrolysed by an alpha-d-mannosidase preparation that contained no detectable beta-d-mannosidase activity. 5. An attempt to prepare o-nitrophenyl beta-d-mannopyranoside led only to o-nitrophenyl alpha-d-mannopyranoside.

| S-EPMC1198361 | biostudies-other

Transition-metal-free silylboronate-mediated cross-couplings of organic fluorides with amines.

Project description:C-N bond cross-couplings are fundamental in the field of organic chemistry. Herein, silylboronate-mediated selective defluorinative cross-coupling of organic fluorides with secondary amines via a transition-metal-free strategy is disclosed. The cooperation of silylboronate and potassium tert-butoxide enables the room-temperature cross-coupling of C-F and N-H bonds, effectively avoiding the high barriers associated with thermally induced SN2 or SN1 amination. The significant advantage of this transformation is the selective activation of the C-F bond of the organic fluoride by silylboronate without affecting potentially cleavable C-O, C-Cl, heteroaryl C-H, or C-N bonds and CF3 groups. Tertiary amines with aromatic, heteroaromatic, and/or aliphatic groups were efficiently synthesized in a single step using electronically and sterically varying organic fluorides and N-alkylanilines or secondary amines. The protocol is extended to the late-stage syntheses of drug candidates, including their deuterium-labeled analogs.

| S-EPMC10070422 | biostudies-literature

Synthesis of Glycosyl Fluorides by Photochemical Fluorination with Sulfur(VI) Hexafluoride.

Project description:This study describes a new convenient method for the photocatalytic generation of glycosyl fluorides using sulfur(VI) hexafluoride as an inexpensive and safe fluorinating agent and 4,4'-dimethoxybenzophenone as a readily available organic photocatalyst. This mild method was employed to generate 16 different glycosyl fluorides, including the substrates with acid and base labile functionalities, in yields of 43%-97%, and it was applied in continuous flow to accomplish fluorination on an 7.7 g scale and 93% yield.

| S-EPMC7783729 | biostudies-literature

Photo-Induced, Phenylhydrazine-Promoted Transition-Metal-Free Dehalogenation of Aryl Fluorides, Chlorides, Bromides, and Iodides.

Project description:In this study, we present a straightforward and highly effective photo-triggered hydrogenation method for aryl halides, devoid of transition-metal catalysts. Through the synergistic utilization of light, PhNHNH2, and a base, we have successfully initiated the desired radical-mediated hydrogenation process. Remarkably, utilizing mild reaction conditions, a wide range of aryl halides, including fluorides, chlorides, bromides, and iodides, can be selectively transformed into their corresponding (hetero)arene counterparts, with exceptional yields. Additionally, this approach demonstrates a remarkable compatibility with diverse functional groups and heterocyclic compounds, highlighting its versatility and potential for use in various chemical transformations.

| S-EPMC10574415 | biostudies-literature

Ultrafast and surfactant-free synthesis of Sub-3 nm nanoalloys by shear-assisted liquid-metal reduction.

Project description:The uniform and surfactant-free synthesis of ultrafine alloy nanoparticles (NPs) still remains an ongoing challenge. Here, we developed a general route for synthesizing sub-3 nm nanoalloys on a carbon support via a shear-assisted liquid-metal reduction (SA-LMR) strategy. The utilization of shearing treatment resulted in the rapid release of electrons from the liquid sodium-potassium (NaK) alloy, which enabled the ultrafast reduction of precursor metal ions to metallic nanoalloys at room temperature. As a model system, Pt-Cu NPs with uniform distribution were synthesized and characterized by spectroscopic and microscopic techniques. The size, composition and structure of the Pt-Cu NPs could be tuned by controlling the volume of liquid NaK alloy and the reaction time. To prove the universality and utility of our method, the binary Pt-M (Fe, Co, Ni, and Cu) and ternary Pt-Cu-Fe nanoalloys deposited on a carbon support were prepared as hydrogen evolution reaction (HER) catalysts. This facile, rapid and universal synthesis technique has the potential to be employed in the large-scale production of nanomaterials and suggests a new direction for nanoalloys.

| S-EPMC9419302 | biostudies-literature

Versatile Glycosyl Sulfonates in β-Selective C-Glycosylation.

Project description:C-Glycosides are both a common motif in many bioactive natural products and important glycoside mimetics. We demonstrate that activating a hemiacetal with a sulfonyl chloride, followed by treating the resultant glycosyl sulfonate with an enolate results in the stereospecific construction of β-linked C-glycosides. This reaction tolerates a range of acceptors and donors, including disaccharides. The resulting products can be readily derivatized into C-glycoside analogues of β-glycoconjugates, including C-disaccharide mimetics.

| S-EPMC7054165 | biostudies-literature

A Metal-free Battery with Pure Ionic Liquid Electrolyte.

Project description:Metal or metal-ion-based batteries represent the mainstream battery technology, in which metal ions either participate in the electrode redox reaction or act as the charge carrier in the electrolyte. The principle guides battery designs and leads to the most widely adopted battery construction of metal-ion acceptor/metal salt in solvent/metal-ion donor. Although these architectures have seen significant progress, there are still many issues with them, including dendrite growth, solid-electrolyte interface corruption, and safety concerns. In this article, the intercalation/deintercalation of organic cations other than metal ions is explored in an all-organic battery composed of organic anode/cathode and pure ionic liquid electrolyte. This metal-free and solvent-free concept has been demonstrated by polyimide/1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide/polytriphenylamine full-cell, through which capacity near theoretical value, more than 5,000 cycling life, rate capability up to 200 C, and remarkable low-temperature performance has been achieved. Our work provides an alternate way of developing future efficient, safe, green, and versatile batteries.

| S-EPMC6482332 | biostudies-literature

Sol-Gel-Synthesis of Nanoscopic Complex Metal Fluorides.

Project description:The fluorolytic sol-gel synthesis for binary metal fluorides (AlF?, CaF?, MgF?) has been extended to ternary and quaternary alkaline earth metal fluorides (CaAlF?, Ca?AlF?, LiMgAlF?). The formation and crystallization of nanoscopic ternary CaAlF? and Ca?AlF? sols in ethanol were studied by 19F liquid and solid state NMR (nuclear magnetic resonance) spectroscopy, as well as transmission electron microscopy (TEM). The crystalline phases of the annealed CaAlF?, Ca?AlF?, and LiMgAlF? xerogels between 500 and 700 °C could be determined by X-ray powder diffraction (XRD) and 19F solid state NMR spectroscopy. The thermal behavior of un-annealed nanoscopic ternary and quaternary metal fluoride xerogels was ascertained by thermal analysis (TG/DTA). The obtained crystalline phases of CaAlF? and Ca?AlF? derived from non-aqueous sol-gel process were compared to crystalline phases from the literature. The corresponding nanoscopic complex metal fluoride could provide a new approach in ceramic and luminescence applications.

| S-EPMC5707579 | biostudies-literature

OFox imidates as versatile glycosyl donors for chemical glycosylation.

Project description:Previously we communicated 3,3-difluoroxindole (HOFox) - mediated glycosylations wherein 3,3-difluoro-3H-indol-2-yl (OFox) imidates were found to be key intermediates. Both the in situ synthesis from the corresponding glycosyl bromides and activation of the OFox imidates could be conducted in a regenerative fashion. Herein, we extend this study with the main focus on the synthesis of various OFox imidates and their investigation as glycosyl donors for chemical 1,2-cis and 1,2-trans glycosylation.

| S-EPMC5499515 | biostudies-literature