CHEMISTRY OF GLYCOSYL TRIFLATES: SYNTHESIS OF<i>β</i>-MANNOPYRANOSIDES

Crich, David

doi:10.1081/car-120016486

Cited by 96 publications

(16 citation statements)

References 48 publications

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“…Many glycosyl triflates have now been characterized by low-temperature NMR methods. , The ensuing chemistry of the glycosyl sulfonates has been reviewed ,− and will not be commented on here. It is, however, appropriate to contrast these methods involving nucleophilic attack of triflate on electrophilic glycosylating species, with the early work on the attempted generation of glycosyl triflates by triflation of anomeric hemiacetals.…”

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confidence: 75%

Trifluoromethanesulfonate Anion as Nucleophile in Organic Chemistry

2017

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Although the triflate ion is not generally perceived as a nucleophile many examples of its behavior as such exist in the literature. This synopsis presents an overview of such reactions, in which triflate may be either a stoichiometric or catalytic nucleophile, leading to the suggestion that nucleophilic catalysis by triflate may be more common than generally accepted, albeit hidden by the typical reactivity of organic triflates which complicates their observation as intermediates.

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confidence: 75%

Trifluoromethanesulfonate Anion as Nucleophile in Organic Chemistry

2017

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“…In comparison, with a donor without the oxazole group, 5y was formed with an α/β ratio of 1:13, and 5z was formed in a literature report of 1:12, revealing the beneficial directing effect in addition to the inherent selectivity. A reported drawback of employing 4,6- O -benzylidenemannosyl donors is the substantially diminished selectivities caused by adverse steric buttressing of bulky O3 groups. Despite subsequent improvements via using sterically minimal propargyl as the O2 protecting group or employing Yu’s o- alkynylbenzoate system, the issue remains with bulky acceptors.…”

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confidence: 99%

A “Traceless” Directing Group Enables Catalytic S_N2 Glycosylation toward 1,2-cis-Glycopyranosides

Zheng

et al. 2021

J. Am. Chem. Soc.

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Generally applicable and stereoselective formation of 1,2-cis-glycopyranosidic linkage remains a long sought after yet unmet goal in carbohydrate chemistry. This work advances a strategy to this challenge via stereoinversion at the anomeric position of 1,2-trans glycosyl ester donors. This S N 2 glycosylation is enabled under gold catalysis by an oxazole-based directing group optimally tethered to a leaving group and achieved under mild catalytic conditions, in mostly excellent yields, and with good to outstanding selectivities. The strategy is also applied to the synthesis of oligosaccharides.

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“…However, stereocontrolled i.e. site selective synthesis of SEs has long been recognized as a significant challenge in carbohydrate chemistry [11][12]. The presence of several secondary hydroxyl groups with almost similar reactivity imposes a barrier on selective esterification [13].…”

Section: Rhamnopyranosides Conformationmentioning

confidence: 99%

The effects of protecting and acyl groups on the conformation of benzyl α-L-rhamnopyranosides: An in silico study

Islam

Rahman

Matin

2021

Turkish Computational and Theoretical Chemistry

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Carbohydrate fatty acid (CFA) esters especially rhamnopyranoside esters having both the hydrophilic and lipophilic nature showed broader applications including anticancer activities. It was reported that appropriate conformation is needed for better activities and conformational distortion reduced antimicrobial functionality. In this context, two different esters series of benzyl α-L-rhamnopyranosides, one with 2,3-O-acetonide group and the other one without acetonide group, were subjected for the density functional theory (DFT) optimization. The optimized structures with 2,3-O-acetonide rhamnopyranoside clearly showed distortion from the regular 1C4 chair conformation while rhamnopyranoside esters without 2,3-O-acetonide functionality exhibited almost regular 1C4 chair conformation. Also, the number and position of acyl group(s) present in the benzyl rhamnopyranoside imposes a small effect on their pyranose chair conformation. Thermodynamic properties including frontier molecular orbitals (FMO) and molecular electrostatic potential (MEP) of both the series of rhamnopyranosides are also discussed which indicated that 4-O-acyl rhamnopyranosides are more reactive than the 3-O-acyl analogues.

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CHEMISTRY OF GLYCOSYL TRIFLATES: SYNTHESIS OFβ-MANNOPYRANOSIDES

Cited by 96 publications

References 48 publications

Trifluoromethanesulfonate Anion as Nucleophile in Organic Chemistry

Trifluoromethanesulfonate Anion as Nucleophile in Organic Chemistry

A “Traceless” Directing Group Enables Catalytic S_N2 Glycosylation toward 1,2-cis-Glycopyranosides

The effects of protecting and acyl groups on the conformation of benzyl α-L-rhamnopyranosides: An in silico study

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CHEMISTRY OF GLYCOSYL TRIFLATES: SYNTHESIS OFβ-MANNOPYRANOSIDES

Cited by 96 publications

References 48 publications

Trifluoromethanesulfonate Anion as Nucleophile in Organic Chemistry

Trifluoromethanesulfonate Anion as Nucleophile in Organic Chemistry

A “Traceless” Directing Group Enables Catalytic SN2 Glycosylation toward 1,2-cis-Glycopyranosides

The effects of protecting and acyl groups on the conformation of benzyl α-L-rhamnopyranosides: An in silico study

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A “Traceless” Directing Group Enables Catalytic S_N2 Glycosylation toward 1,2-cis-Glycopyranosides