Advances in Stereoselective 1,2‐<i>cis</i>Glycosylation using C‐2 Auxiliaries

Mensink, Rens A.; Boltje, Thomas J.

doi:10.1002/chem.201700908

Cited by 57 publications

(37 citation statements)

References 69 publications

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“…Stereoselective glycosylation can be achieved by the S N 2-like displacement of a contact ion pair or covalent intermediate such as glycosyl triflates, 3 sulfonium ions, 4 , 5 and dioxolenium ions 6 ( Scheme 1 ). Reactions via this pathway are well studied as the reaction intermediates can be characterized by low temperature NMR spectroscopy.…”

mentioning

confidence: 99%

Direct Experimental Characterization of Glycosyl Cations by Infrared Ion Spectroscopy

Elferink¹,

Severijnen

Martens

et al. 2018

J. Am. Chem. Soc.

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Glycosyl cations are crucial intermediates formed during enzymatic and chemical glycosylation. The intrinsic high reactivity and short lifetime of these reaction intermediates make them very challenging to characterize using spectroscopic techniques. Herein, we report the use of collision induced dissociation tandem mass spectrometry to generate glycosyl cations in the gas phase followed by infrared ion spectroscopy using the FELIX infrared free electron laser. The experimentally observed IR spectra were compared to DFT calculated spectra enabling the detailed structural elucidation of elusive glycosyl oxocarbenium and dioxolenium ions.

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confidence: 99%

Direct Experimental Characterization of Glycosyl Cations by Infrared Ion Spectroscopy

Elferink¹,

Severijnen

Martens

et al. 2018

J. Am. Chem. Soc.

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“…In contrast, the construction of our desired 1,2- ci s α- O -glucoside is much more challenging. It requires glycosyl donors having nonassisting functionality at C-2 position, and even so, the reaction normally produces a mixture of α and β isomers [ 30 , 31 , 32 ]. In this work, we chose 2,3,4,6-tetra- O -benzyl-glucopyranosyl trichloroacetimidate 6 as the glucosyl donor, which was synthesized from 2,3,4,6-tetra- O -benzyl glucose with trichloroacetonitrile in dichloromethane (DCM) using anhydrous potassium carbonate as catalysis (98% yield, α:β ≈ 1:4) [ 33 , 34 ].…”

Section: Resultsmentioning

confidence: 99%

First Total Synthesis of 5′-O-α-d-Glucopyranosyl Tubercidin

Ouyang¹,

Huang²,

Yang³

et al. 2020

Marine Drugs

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The first total synthesis of 5′-O-α-d-glucopyranosyl tubercidin was successfully developed. It is a structurally unique disaccharide 7-deazapurine nucleoside exhibiting fungicidal activity, and was isolated from blue-green algae. The total synthesis was accomplished in eight steps with 27% overall yield from commercially available 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d-ribose. The key step involves stereoselective α-O-glycosylation of the corresponding 7-bromo-6-chloro-2′,3′-O-isopropylidene-β-d-tubercidin with 2,3,4,6-tetra-O-benzyl-glucopyranosyl trichloroacetimidate. All spectra are in accordance with the reported data for natural 5′-O-α-d-glucopyranosyl tubercidin. Meanwhile, 5′-O-β-d-glucopyranosyl tubercidin was also prepared using the same strategy.

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“…Although great progress has been made in oligosaccharide synthesis, the assembly of bacterial glycans presenting rare structural modifications and challenging cis-glycosidic linkages still presents a major obstacle as the reactivity of the required building blocks is not well understood. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] We here report an approach to map the reactivity-stereoselectivity relationships for the tertiary C-sugar caryophyllose and its truncated counterpart yersiniose A (YerA; Figure 1A). This has allowed us to effectively construct the Car-Car-NAcFuc LOS-IV fragment 1 ( Figure 1C), and related shorter fragments, equipped with an alkene spacer for future conjugation purposes.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Reactivity–Stereoselectivity Mapping for the Assembly of Mycobacterium marinum Lipooligosaccharides

et al. 2020

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The assembly of complex bacterial glycans presenting rare structural motifs and cis-glycosidic linkages is significantly obstructed by the lack of knowledge of the reactivity of the constituting building blocks and the stereoselectivity of the reactions in which they partake. We here report a strategy to map the reactivity of carbohydrate building blocks and apply it to understand the reactivity of the bacterial sugars, caryophyllose, a rare C12-monosaccharide, containing a characteristic tetrasubstituted stereocenter. We mapped reactivity-stereoselectivity relationships for caryophyllose donor and acceptor glycosides, by a systematic series of glycosylations in combination with the detection and characterization of different reactive intermediates using experimental and computational techniques. The insights garnered from these studies enabled the rational design of building blocks with the required properties to assemble mycobacterial lipooligosaccharide fragments of M. marinum.

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Advances in Stereoselective 1,2‐cisGlycosylation using C‐2 Auxiliaries

Cited by 57 publications

References 69 publications

Direct Experimental Characterization of Glycosyl Cations by Infrared Ion Spectroscopy

Direct Experimental Characterization of Glycosyl Cations by Infrared Ion Spectroscopy

First Total Synthesis of 5′-O-α-d-Glucopyranosyl Tubercidin

Reactivity–Stereoselectivity Mapping for the Assembly of Mycobacterium marinum Lipooligosaccharides

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