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Glycal assembly by the in situ generation of glycosyl dithiocarbamates.

ABSTRACT: Glycal assembly offers an expedient entry into ?-linked oligosaccharides, but epoxyglycal donors can be capricious in their reactivities. Treatment with Et(2)NH and CS(2) enables their in situ conversion into glycosyl dithiocarbamates, which can be activated by copper triflate for coupling with complex or sterically congested acceptors. The coupling efficiency can be further enhanced by in situ benzoylation, as illustrated in an 11-step synthesis of a branched hexasaccharide from glucals in 28% isolated yield and just four chromatographic purifications.

SUBMITTER: Padungros P

PROVIDER: S-EPMC3412062 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature

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Glycal assembly by the in situ generation of glycosyl dithiocarbamates.

Padungros Panuwat P Alberch Laura L Wei Alexander A

Organic letters 20120611 13

Glycal assembly offers an expedient entry into β-linked oligosaccharides, but epoxyglycal donors can be capricious in their reactivities. Treatment with Et(2)NH and CS(2) enables their in situ conversion into glycosyl dithiocarbamates, which can be activated by copper triflate for coupling with complex or sterically congested acceptors. The coupling efficiency can be further enhanced by in situ benzoylation, as illustrated in an 11-step synthesis of a branched hexasaccharide from glucals in 28% ...[more]

PMID: 22686424

Similar Datasets

Glycosyl dithiocarbamates: β-selective couplings without auxiliary groups.

Project description:In this article, we evaluate glycosyl dithiocarbamates (DTCs) with unprotected C2 hydroxyls as donors in β-linked oligosaccharide synthesis. We report a mild, one-pot conversion of glycals into β-glycosyl DTCs via DMDO oxidation with subsequent ring opening by DTC salts, which can be generated in situ from secondary amines and CS2. Glycosyl DTCs are readily activated with Cu(I) or Cu(II) triflate at low temperatures and are amenable to reiterative synthesis strategies, as demonstrated by the efficient construction of a tri-β-1,6-linked tetrasaccharide. Glycosyl DTC couplings are highly β-selective despite the absence of a preexisting C2 auxiliary group. We provide evidence that the directing effect is mediated by the C2 hydroxyl itself via the putative formation of a cis-fused bicyclic intermediate.

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Electrochemical generation of glycosyl triflate pools.

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PRACTICAL SYNTHESIS OF AROMATIC DITHIOCARBAMATES.

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Electrochemical generation of 2,3-oxazolidinone glycosyl triflates as an intermediate for stereoselective glycosylation.

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Glycosyl-T expression in NB cells

Project description:Dr. Ladisch's work focuses on the establishment of the biological significance of gangliosides that are shed by tumor cells, particularly those involved in pediatric cancers, including brain tumors and neuroblastoma. These studies are directed toward illuminating the hypothesis that shed gangliosides enhance tumor formation, possibly both by inhibiting the antitumor immune response and by enhancing growth factor-induced signaling and proliferation of fibrobalsts and vascular endotheilial cells in the tumor microenvironment. Delineation of the signaling pathways affected by ganglioside exposure is currently under study.

2011-01-07 | GSE26481 | GEO

Observation of the controlled assembly of preclick components in the in situ click chemistry generation of a chitinase inhibitor.

Project description:The Huisgen cycloaddition of azides and alkynes, accelerated by target biomolecules, termed "in situ click chemistry," has been successfully exploited to discover highly potent enzyme inhibitors. We have previously reported a specific Serratia marcescens chitinase B (SmChiB)-templated syn-triazole inhibitor generated in situ from an azide-bearing inhibitor and an alkyne fragment. Several in situ click chemistry studies have been reported. Although some mechanistic evidence has been obtained, such as X-ray analysis of [protein]-["click ligand"] complexes, indicating that proteins act as both mold and template between unique pairs of azide and alkyne fragments, to date, observations have been based solely on "postclick" structural information. Here, we describe crystal structures of SmChiB complexed with an azide ligand and an O-allyl oxime fragment as a mimic of a click partner, revealing a mechanism for accelerating syn-triazole formation, which allows generation of its own distinct inhibitor. We have also performed density functional theory calculations based on the X-ray structure to explore the acceleration of the Huisgen cycloaddition by SmChiB. The density functional theory calculations reasonably support that SmChiB plays a role by the cage effect during the pretranslation and posttranslation states of selective syn-triazole click formation.

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