An α-selective, visible light photocatalytic glycosylation of alcohols with selenoglycosides

Spell, Mark L.; Wang, Xiaoping; Wahba, Amir E.; Conner, Elizabeth S.; Ragains, Justin R.

doi:10.1016/j.carres.2013.01.004

Cited by 47 publications

(23 citation statements)

References 55 publications

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“…Both laboratories employed either carbon tetrabromide or bromotrichloromethane as an auxiliary oxidant and the exact mechanisms these reactions remain unclear. 94–95 In a related process it has also been demonstrated that anomeric hemiacetals may be converted to glycosyl bromides by white light irradiation in the presence of a ruthenium-based photocatalyst and carbon tetrabromide. 96 The Ragains group further demonstrated that diphenyl diselenide can serve as a simple organic photocatalyst for the activation of selenoglycosides in the presence of carbon tetrabromide.…”

Section: Counterion and Additive Effectsmentioning

confidence: 99%

“…In the this case the mechanism is considered to involve homolytic abstraction of a bromine atom from the tetrabromide by a phenyl selenyl radical to give phenylselenyl bromide, which then serves as the promotor in a more traditional mechanism. 95 Although not catalytic, the Crich and Toshima laboratories also reported methods for the white light photochemical activation of selenoglycosides and thioglycosides employing, respectively, N -methylquinolinium hexfluorophosphate and DDQ as the photoactivated oxidants. 97–98 …”

Section: Counterion and Additive Effectsmentioning

confidence: 99%

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A propos of glycosyl cations and the mechanism of chemical glycosylation; the current state of the art

Bohé

Crich

2015

Carbohydrate Research

125

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An overview of recent advances in glycosylation with particular emphasis on mechanism is presented. The mounting evidence for both the existence of glycosyl oxocarbenium ions as fleeting intermediates in some reactions, and the crucial role of the associated in counter ion in others is discussed. The extremes of the SN1 and SN2 manifolds for the glycosylation reaction are bridged by a continuum of mechanisms in which it appears likely that most examples are located.

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Section: Counterion and Additive Effectsmentioning

confidence: 99%

Section: Counterion and Additive Effectsmentioning

confidence: 99%

A propos of glycosyl cations and the mechanism of chemical glycosylation; the current state of the art

Bohé

Crich

2015

Carbohydrate Research

125

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“…Selenoglycosides can also be used as tools for the investigation of sugar‐protein interactions . From a synthetic point of view, they show a unique reactivity as glycosyl donors: indeed, the C‐Se bond can be readily ionized under photo‐chemical and electro‐chemical conditions, generating very reactive cationic and radical‐cationic species. However, the preparation of selenoglycosides involves major limitations: generally, only one anomer is accessible, the synthesis is not trivial and the substrate scope narrow (for instance, unprotected sugars are not tolerated under the reaction conditions).…”

Section: Exocyclic Oxygen Replacementmentioning

confidence: 99%

Design and synthesis of glycomimetics: Recent advances

Tamburrini

Colombo

Bernardi

2019

Medicinal Research Reviews

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In the past few decades, our understanding of glycan information‐encoding power has notably increased, thus leading to a significant growth also in the design and synthesis of glycomimetic probes. Combining data from multiple analytical sources, such as crystallography, nuclear magnetic resonance spectroscopy, and other biophysical methods (eg, surface plasmon resonance and carbohydrate microarrays) has allowed to shed light on the key interaction events between carbohydrates and their protein‐targets. However, the low metabolic stability of carbohydrates and their high hydrophilicity, which translates in low bioavailability, undermine their development as drugs. In this framework, the design of chemically modified analogues (called carbohydrate mimics or glycomimetics) appears as a valid alternative for the development of therapeutic agents. Glycomimetics, as structural and functional mimics of carbohydrates, can replace the native ligands in the interaction with target proteins, but are designed to show enhanced enzymatic stability and bioavailability and, possibly, an improved affinity and selectivity toward the target. In the present account, we specifically focus on the most recent advances in the design and synthesis of glycomimetics. In particular, we highlight the efforts of the scientific community in the development of straightforward synthetic procedures for the preparation of sugar mimics and in their preliminary biological evaluation.

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“…glycosyl donors in current preparative carbohydrate chemistry. [36] Classicalm ethods for CÀSe bond formation involve nucleophilic displacementf rom an anomeric bromide or through a series of manipulations of glycals and their corresponding 1,2anhydro sugars. These protocols use protected glycosyl donors and generallyp rovidet he 1,2-trans isomers.…”

Section: Selenoglycosidesmentioning

confidence: 99%

Rethinking Carbohydrate Synthesis: Stereoretentive Reactions of Anomeric Stannanes

Zhu

O’Neill

Rodriguez

et al. 2018

Chemistry A European J

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In this Concept article, we highlight recent advances in the synthesis and applications of anomeric nucleophiles, a class of carbohydrates in which the C1 carbon bears a carbon-metal bond. First, we discuss the advantages of exploiting the carboanionic reactivity of carbohydrates and the methods for the synthesis of mono- and oligosaccharide stannanes. Second, we discuss recent developments in the glycosyl cross-coupling method resulting in transfer of anomeric configuration from C1 stannanes to C-aryl glycosides. These highly stereoretentive processes are ideally suited for the preparation of and was demonstrated in the synthesis of antidiabetic drugs. Next, we highlight the applications of glycosyl cross-coupling method to the preparation of Se-glycosides and in glycodiversification of small molecules and peptides. These reactions proceed with exclusive anomeric control for a broad range of substrates and tolerate carbohydrates with free hydroxyl groups. Taken together, anomeric nucleophiles have emerged as powerful tools for the synthesis of oligosaccharides and glycoconjugates and their future applications will open new avenues to incorporate saccharides into small molecules and biologics.

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An α-selective, visible light photocatalytic glycosylation of alcohols with selenoglycosides

Cited by 47 publications

References 55 publications

A propos of glycosyl cations and the mechanism of chemical glycosylation; the current state of the art

A propos of glycosyl cations and the mechanism of chemical glycosylation; the current state of the art

Design and synthesis of glycomimetics: Recent advances

Rethinking Carbohydrate Synthesis: Stereoretentive Reactions of Anomeric Stannanes

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